Sunday, May 27, 2018

Things I've made: Tale of the two Vendel helmets

    This is a project I did a number of years ago, but was recently asked about it, so I thought I'd post something about the helmets I made.
Years ago I made a pre-Viking age, or "Vendel" decorated helmet for a TV producer as a private commission.  At the time, I was pretty happy with it. It was only the second time I did "repousse', the tooling of metal. The first time was for the "Viking" box used to hold the Loki Mask in the movie "The Mask"
However, as time goes on, hopefully, one learns more, and sees things in a new light. As I became more educated in the Vendel period, the light came on, and I realized this helmet was not very good.
Now, of course, I was compelled to make one that was better. But my life is a busy one, and was many years before I would make the time to do this.

just as I started gathering materials on the Vendel period together and planning what I would make, a friend who was managing my rental department, expressed his desire of owning one of these decorated helmets or "field crowns". Skip, who, was heavily into Viking history,  had been doing a great job running the department and I always felt I couldn't afford to pay him enough. I felt this would be a nice thank you. Plus, if he knew I was making one of these, he would be jealous, so I thought, I'll just make two!
This is how my life often goes; No time to build one of something, but two of them, I'll figure out how to do it. (Although, I'm still trying to figure out how to get those two Ferrari's!)
The trick was, how to keep Skip from discovering what I was planning.

The Vendel period is a modern scholarly classified age in Sweden from 550 to 790 AD. Many of the extant swords and helmets are highly decorated and had similarities to late Roman ridge helms.
There are around 26 helmets or helmet fragments that have been found across Scandinavia, Northern Europe and eastern Russia. I don't know how many swords have been found.
Finds from graves at Vendel and Valsgärde show that Uppland, or the east-central part of Sweden, was an important area during this time and many of these finds are very well documented.
Although detailed documentation was difficult to come by, back in 2004 when I started, but I did manage to find a couple of Swedish publications that had some excellent photos.
Eventually I decided to make a helmet for myself similar to the Valsgärde 5, but I had to find out what Skip fancied.  Skip is a stickler for authenticity and I had planned on letting him see what I was making for myself, but I needed to keep him in the dark about the second one for him, while still get feed back on what he was dreaming of. After some surreptitious questioning, I found out he always liked the Vendel 14 helmet.
Interestingly, when I showed him an image of the Vendel 14, as it is now in a museum, he said, no, not that one. As we flipped through the book, he spotted a drawing of the one to which he was referring. The helmet he had admired for all those years was an early archaeological drawing of what they thought the Vendel 14 helmet would look like, once it was removed from the dirt and rust in which it was entombed. Once it was cleaned and reconstructed however, it looked very little like this drawing. (This incorrect drawing is still being published as a depiction of the "Vendel 14" helmet.)
Skip was pretty bummed because he realized he was in love with a helmet that was not a real thing. But I pointed out, the drawing is in keeping with the style of other helmets that had been found and it was still a viable choice. I really hoped he agreed with my assessment, because I really didn't like the real Vendel 14 helm. (Although, now it's grown on me a bit) He did and so I continued my research and planning.
Valsgärde 5
Vendel 14

I would make the helmets from modern sheet steel, and since we were likely to use these in reenactment battles in Europe, I chose to make them in 1050 spring steel, so the steel could be hardened. This process was all pretty straight forward, although the lattice work on the Valsgärde 5 turned out to be a little tricky. I needed to make sure all of the small bands lined up nicely with each separate panel. (Now, new research I have found, suggests that these areas were covered with fabric, and not visible!)
The decoration was more unfamiliar to me, so that was the biggest hurdle on this project.

First, I had to find out how these were made in the period and then see if I had a way to make them with the skills and tools I had available to me. The main decorated panels were made of thin "foil" sheets of metal, pressed over bronze relief plates. The center crest seemed to be fabricated or cast and the eyebrows and crest terminals were cast. All of the helmets I have researched have some type of copper alloy for these decorations, but Skip wore tons of really nice silver Viking jewelry. So I planned to make his decorations with fine silver.
To save time, I came up with a technique of making the pressed decorative panels by using a etched magnesium plate. These were used for creating rubber stamps and in the printing profession. The advantage to the acid etched magnesium, is the magnesium cuts extremely fast with the correct acid, so fine details can be made right next to deep, large details. If you are interested in this process, here is a nice video on how these mag plates are made.
Once I drew the artwork, I scanned it into the computer and did some corrections and scaling. I then printed out full size artwork to check porportion and spaceing of the design elements.
I would need to test metal thickness for the finished foil plates and how the size and depth of the etching worked with this foil.
There were a lot of tests. But, eventually, I decided to use .005" fine silver and brass pressed into the mag plates. People have asked, why not Sterling Silver; Sterling is a harder alloy that contains  92.5% by weight of silver and 7.5% of other metals, usually copper, so it is harder. Fine silver is 99.9% silver, so it can be made softer. This turns out to be critical with my process. To impress the foil, I used wet leather and my 20 ton mold press. The wet tooling leather (flesh side down) was chosen over rubber, because the rubber acts as a "single surface" and would bridge certain fine detail. The wet leather on the other hand was more granular and pressed into these details nicely. Once the foils were pressed, I used small metal ball and spoon shaped tools to press or "sculp" more dimension into the foils by working the backside of each foil panel, while it was supported in pitch. Another element is the ribbed strips that boarder the panels. This was made by turning a rolling die on my lathe and rolling each strip through the mill. This of course required a few steps, annealing, straightening and re-annealing.

For the cast details I carved waxes instead of carving the mold from soft stone, like the originals had been made. Part of my job making props is to figure out techniques that can achieve a specific look, but can produce the item faster or in a way more familiar to my skill set.

Since Skips persona in the living history was more Viking then Vendel, I formed the fine silver eyebrow pieces from thick sheet and did punch decoration, which was more the style of Viking work in later centuries. These pieces were placed in pitch for support and I made a variety of steel punches with the needed shapes.

The other trick piece to make was the support for the mail drape across the back of each helm. This needed to be a hollow tube, curved in a semicircle, with a set of flanges sticking up, in order to fit the "tubes" to the lower rim of each helmet. In addition, each tubular section needed to have slices cut in at intervals in which to fit each ring on the top edge of the mail. The links of the mail are then held in place with a wire threaded through the links inside this tube. Nearly all the edges have a rolled boarder of brass or silver. This was fabricated by starting with strips, then pulling them through a draw die so they curl up like a tube, Once annealed, the can be formed around the edge of the plate.

The last task, was making rivets for the silver helmet, since I never found a source for silver rivets.

In the end, I finally did get both helmets completed. Here they are.

I told someone that these came as a kit: All flat material, no instructions and one of them was missing the rivets!....their response......"Where did you buy the kits?"

Thanks for looking.

Saturday, May 26, 2018

Decorating a full Greenwich garniture: Part 4: The Aha moment.

At this point I have done well over 60 tests of formulas and application times of this period etching paste, but I'm still very frustrated by the inconsistencies of my results. Something is affecting the cutting ability of the paste, and I have not pinpointed what it is. There have been very few times in my 40 year career of learning a craft, that I have encountered something that, while it works, it does not work as well as my gut tells me it should or as constantly as it should, within obvious parameters.
 In all of these experiments, I have been guided by research originally done by Jonathan Tavares and Robert MacPherson (Mac). In  Mac's research, he has gathered together many sources and recipes here. While Mac's research shows a variety of recipes, with a wide range of ingredients, it seems the copper sulfate / salt & vinegar shows up a often. It is also the one that Jonathan Tavares used for his etching, for the Nova special "Knights In Shinning Armour".

 Mac's research shows one of the additional ingredients for the C.S./salt & vinegar recipe is charcoal, so this is why I have been trying it in the more recent tests. So far, I have been creating my paste batches using volume as a measurement. With the inconsistent results I had been getting, perhaps I'm not being as accurate as I need and I'm sure my notes have been insufficient.
For the new tests, because I was going to make very small batches, and in an effort to be more accurate and consistent, I switched to proportioning my ingredients by weight.
In switching to weight, I overlooked the fact that C.S. and salt are much denser (heavier), than an equal volume of charcoal. As a result, these small batches, now proportioned by weight, ended up with significantly more charcoal than my past mixes. At first I thought, this was way too much charcoal, but I figured, since they are already in the cup, I may as well test them as they are.

Turns out, of the 15 different formulas in this test, the best results came from the recipe with the large proportion of charcoal:
This is the formula that etched the deepest:
20g - Copper Sulfate
20g - Salt
5g - Bone charcoal (same granular size as the CS)
5g - Activated charcoal (Powder)
15% vinegar (to wet to damp sand consistency)

This paste etched deeper and was less damaging to the resists than the others.
In hindsight, this was nearly 4 times the volume of charcoal than my previous recipes.
I did another small test and got the same results, so I decided to etch my next piece of armour, the right cuisse.
Here are all the pieces "masked" off with the vinyl and asphaltum dots.

With the amount of surface area and the necessity to apply three consecutive batches of paste,this meant I would be mixing up one of the largest batches I have made. So I estimated a volume, 40 times my sample batch.
800g - C.S.
800g - Salt
200g - Bone charcoal (same granular size as the CS)
200g - Activated charcoal (Powder)
600g - 15% vinegar
Outside temp was 92f / 30c
(While the pieces were initially in direct sun,
I put up a piece of plywood to shade them.)
3 - 90 minute etches

The results were fantastic!
Very deep etch, very little damage to the resists (In fact no repair required)

EDIT-Current formula (as of July 2021) After over 100 tests and 99% of the armour complete, the formula I'm using now with satisfactory results is:
100g fine salt (Salt flour)
100g Copper sulfate fine crystals
25g Bone charcoal
13g activated wood charcoal
Distilled water to make it a thick paste.
The reaction with the salt, will cause the material to freeze, so after mixing, you need to let the paste sit for and hour or so, and then t\remix it. NOTE: Do not make your initial mixture too wet, as after you remix it, the salt gives up some water, and the paste gets wetter.
If it is too runny, you can add charcoal to thicken. I have found 3 or 4 90 minute etches (fresh paste for each) gives you considerable depth, equivalent to late 16th C armour.

Now this etch depth is more in line with the real armour. Because the Buckhurst armour has a painted background, behind the central gilded area, a very deep etch makes adding paint to these backgrounds much easier.

While I'm delighted with the success, I'm still not 100% convinced it is only the charcoal content that is giving me this great result. I also suspect the temperature may have something to do with it. Because of my scant notes, I'm not sure if my earlier successes were a result of a warm sunny day.

But, given these stellar results, I started on the left cuisse.

Of course, as soon as I get the left fully masked and ready to etch, the weather in Southern California is overcast and drizzly, for the whole week. Then, we get some nice warm days and I get tied up with real work. Finally a sunny warm weekend and I'm able to etch the other leg. Using the same formula I apply the first batch. But this time the asphaltum resist, is not surviving perfectly as it did previously. WHAT THE H#$@!^

I'll have to reapply dots. While I have gotten pretty quick at this, there are 2400 dots just on the knee. This puts me back another day so I can make sure the dots are fully dry. The second two applications go well.
But, during the cleaning of the paste, I change my approach. I had been carefully scraping a majority of the paste off with a tongue depressor into a bucket, and then rinsing the remaining paste off under running water. I had been doing this to avoid washing too large a volume of CS and salt onto the ground or into the drain. However, I was now concerned with damaging the resists and was not enthused with the idea of another ten thousand dot repair job. So I used just water on a couple of pieces to see how this affected the outcome. While one of these pieces was under the running water, I saw a glint of copper within the volume of paste. Upon closer inspection, I could clearly see metallic copper crystals forming up into the paste, away from the steel.
That was the aha moment.

What is the most important part of a sponge? The holes.
I had been adding the charcoal as an "ingredient", but now, with the increased volume, it was more of a "filler". The result was, the metallic copper was no longer forming directly on the steel surface, blocking the effectiveness of the paste. The copper was now being drawn up into the "holes" the charcoal was providing, keeping the steel surface clear, allowing the paste to remaining active and aggressive. I had not noticed this earlier, because I was scrapping this formation off. When the copper is drawn up into the paste, it also means the paste can be left on much longer and still be effective. This now explains the other thing Mac's period sources say, which is too apply the paste a small fingers width in thickness. When the copper was forming on the steel, and keeping the paste from working, it was clear to see this extra paste thickness was being wasted, something one wouldn't expect from a period process, the wasting of material. Now, all of the "finger thickness" of paste was being utilized. The second aha moment.

Other than why the asphaltum dots came off on the second leg, and not the first, I feel I finally have a handle on making this paste work consistently and effectively. I plan to test the limits of paste application times by doing multi hour tests, but for now, I'm confident I can move on.

 Both legs are now completely etched and I'm pretty happy with the results.


The etching I see on extant armour seems to show etching depths increasing over the 16th century and by the 1580's the etch depths are significant. There also seems to be less etch depth on Italian armour than on German armour. With my findings, of what the charcoal is doing, I'm wondering if this same "discovery" happened over many years in the development of this paste. Or the different workshops handing down what they knew, resulted in one formula being more effective than another.

On to the gauntlets......

Saturday, May 12, 2018

Decorating a full Greenwich garniture: Part 3: Still things to learn.

So, by a fortunate series of work related events, I found myself needing to go to South Africa, by way of London. This would mean, with an added lay over, I could visit the Wallace museum in London, where the original armour resides. It would also be nice to visit with Dr. Tobias Capwell, the armour curator at the Wallace. 
Dr. Capwell was gracious enough to take time out of his Monday morning to open up the A62 case and allow me to compare my etching samples to the original. While I was excited by this fortuitous opportunity, putting  your work up next to the original can be scary, since no matter how close you think you are, a side by side comparison will almost always reveal differences instantly. (some times major ones)
This was the case with my etching samples. While my armour is considerably larger than the original, and as a result I have had to enlarge the decorative pattern, I was not prepared to see such a huge difference in dot size.
The original Greenwich armour was considered a moderate decoration option when it was made in 1585. I have learned from Dr. Capwell, there are 4 or 5 known surviving (incomplete and complete) examples with this same etched design.
 The example in the Wallace, which I have been using as my main reference, has dots that are about half the size of the ones I have done. Being half the size, there are also about twice as many.
 The main part of the etched design seem to be pretty close between mine and the original, especially when you take into account my suit is so much larger. But, I will have to experiment with application and etching of these new smaller dots, since the resist can come loose after a number of paste applications.
It was not possible to open the front of the display case, only the shallow side sections, so some of the pictures had to be taken at odd angles or through the glass of the case, but they are still very useful in showing the differences.

Here is the Left lower leg, next to the original. It is a little deceiving because my ungilded piece has more contrast in the etched areas, but I'm pretty happy with the general pattern. It is also clear to see how much bigger my armour is. Now the average height at the time was maybe 5'8" and today it's 5'9" to 5'10", but at 6'3" I'm still tall for today, so my leg armour looks giant next to this one, made for a fellow 5'6". (Yes, they are side by side)
This is the exact reason I started with the greaves, because, while I thought I had a good idea on what needed to be done, I figured if there was any adjustments to be made, better to figure it out before I got to the upper part of the armour. 

The is one of my earlier test pieces next to the decoration on the reinforce breastplate. Being an early test, I didn't worry about lost dots in the pattern, but here you can clearly see my dots are much too large and not nearly dense enough, even given the scaled up main pattern. Also, this being the larger part of the pattern on the original breastplate, the floral work inside the figure eight is denser than my sample, which is a copy of the greave pattern, which has smaller floral work.
My sample also has the two different boarder vine patterns. Clearly the right side one is closer to the original armour.
The plan , if I can produce the smaller dots consistently, is to gradually make them smaller and denser as I work up the armour. So that the upper part of the suit is closer to the original. Given the over all enlargement of the design, I probably won't go exactly as small as the original, but I will try for something much closer than I am now.

I have not been satisfied with the overall depth of my etched pieces. While some pieces seem pretty good, others are not. Consistency seems be elusive. Longer etch times seem to damage the vinyl resist, partially due to the metallic copper deposits and this causes the paste gets underneath and degrades the original surface. Mac's research into etching pastes has recipes which include charcoal. We have suspected this may have some type of conveyor like effect, either to bring the active etching ingredients to the surface of the steel, or remove copper. Before my trip, I ordered some to experiment with. I received both "activated" charcoal powder and the Cowboy charcoal Mac referenced. The limited test I have done do not show any clear advantage of one over the other. They both seem to reduce the metallic copper deposits on the steel surface when the etch paste is removed. This makes surface cleaning between etchings much easier and less destructive to the resists. (My ratio was 4 prts. CS / 2 prts salt / 1 prt charcoal powder)
My brother, who does a lot with 19th century guns, mentioned bone charcoal as being very desirable for case hardening. A little research on bone charcoal revealed some research done in using this type of charcoal to absorb copper contamination in water and found it to be very effective. I ordered some and will test it this week to see if it improves the copper absorption from the steel surface.

The other issue I wanted to address is the size of the dots on my samples. Since my trip to the Wallace showed my background dots where considerably larger than the original. I had spent the long 10 flight back to LA pouring over my reference pictures again and comparing those to what I had just shot with my example next to the A62. I was also going over in my mind what I needed to change, as far a technique, in order to apply the tiny dots.
Using the "hena" plastic bottle to apply the dots smaller turns out to be quite easy and in fact, I have gone the other way and the dots now may be too small, given that the pattern for my armour has been enlarged to account for the armour being bigger. 
Here are tests with smaller dots:
While the overall size is a pretty good match, I'm not sure the smaller dots work as well, so I'll probably split the difference.
The other thing I'm not happy with is the gold. It is not nearly deep enough in color. As you can see by the above photograph, (more apparent in the side by side images in my earlier post) the original has a much yellower gold, a result of the much heavier gold deposit using the fire gilding process.
In this sample, I used a torch to blue the edges and as a result the gold was slightly discolored. I may be able to use this to my advantage, given that the salt bluing, with its more controlled temperature gave the gold an even orange hue. With a reapplication of gold, this color was corrected while still retaining a little of its darker color.

This latest sample has very good depth. A result of 5 paste applications at 1 hour each and a 6th application at 12 hours. With the charcoal added to the paste, the vinyl was less effected by the copper deposits. I also brushed some of the asphaltum resist over the entire surface and cleaned it off with solvent. My hope was this would leave trace amounts in the corners where the vinyl met the steel, hopefully "sealing" the vinyl to the steel a little more effectively. The combination of this and the carbon defiantly improved the vinyls ability to survive repeated cleanings. The last 12 hour etch did get under both the vinyl and the asphaltum dots, so it may not need to be left as long. Perhaps 6 hours will be better.
I have the artwork and vinyls cut for the right greave and will get those applied this week and should have the second greave completed in the next few days. Then on to the cuisses.
I've done some more tests and it seems the bone charcoal is pulling more of the copper away from the surface, or at any rate, it makes cleaning the copper deposit off the steel much easier between etches. It also seems to allow for longer etch times with greater affect. The bone charcoal I have has a slightly larger grain than table salt.
I've completed the right greave front plates and used the bone charcoal mix for 3 hours and it seemed to etch effectively.
My ratio for these tests was 4 parts (By volume) Copper Sulfate - 2 parts salt - 1 part bone charcoal -1 part 15% vinegar. I put the powdered components in a bucket with the snap on lid, then shake to mix thoroughly. Then add the vinegar and shake again. Let sit for 1 to 2 hours, shake vigorously again. 12 to 24 hours later, the paste is like guacamole. With the charcoal, age does not seem to effect the paste's etching rate noticeably.
I have made some tests with smaller, more consistent dots and these are looking much better. Although, I now see I have the dots too dense.
Bluing: The study that was done of the Buckhurst's color, concluding it was steel exposed to atmosphere at 250 c, this temp does not seem to work, with the technique I'm using. In the salt, at 250 c (482 f) the color was very pale straw, barely perceivable. It wasn't until 300 c or 580 f that it shifted to blue. I got an amazing color and the pen plated gold got a little yellower, not as orange as the previous test at 650 f. The photo doesn't show the gold as well as it looks in person, but, it's still "weak". Mac has pointed out that over time (unknown duration hours or weeks) the blue color may be achieved at the 250 c temp. But in the salt, the color was reached in a minute or so at this higher temp and seemed controllable. Of course, this mean a very big container of 500 degree salt for the breastplate and such. The heat treat company may have a tank with a material I can use, if they are willing.
There is a little bit of spotting, which I believe was surface contamination. The surface is also sensitive to finger prints, even with two coats of paste wax.

The test here was pen plated with 24k gold and I was not thinking and forgot to wire brush, per Mac's advice, the etched areas before plating, resulting in the background areas being a bit gray. The pen plating is still paler than the real armour, but, it does shift a bit in color with the bluing, and gets a touch richer yellow, which is desirable. I'm still on the fence about fire gilding.
Since the real armour shows no signs of gold on the background dots, this means they were either blue, like the rest of the bare steel, or had been cleaned off to be silver. After gilding, I cleaned off an area of dots, in the upper left and let the dots turn blue. The effect in my opinion was a bit drab looking, so, rather hastily, I sanded the blue off to see the effect. I think I like the silver dots.
I finished etching the right greave. While I'm happy with the improvements in artwork and scale of the design elements, I'm still not completely happy with the consistency of the etching, nor the ultimate depth I'm getting. There is some variables I have been unable to pin down.
Here is a good look at the progression I've made with the quality and neatness of the artwork and the gold plating. (Old to new - left to right)

To address the etch depth and consistency, I thought I would do a formula test.
 I made three different formulas of etch paste (by weight):
#1- 20 grams of Copper Sulfate / 60 g of salt
#2- 40g C.S / 40g salt
#3- 60g C.S. / 20g salt 
Then after thoroughly mixing the two powders together, I split these into two sets. To one set I added 15g of bone charcoal to the 2nd set I added 30g of bone charcoal. The 30g set I labeled "A" (1A, 2A, 3A)
To these 6 batches I added 15g on 15% vinegar and mixed.
I had final mixtures of:
#1- 10 g C.S. / 30 g S. / 15g B.C. / 15g V.
#2- 20g C.S / 20g S. / 15g B.C. / 15g V.
#3- 30g C.S. / 10g S. / 15g B.C. / 15g V.
#1A- 10 g C.S. / 30 g S. / 30g B.C. / 15g V.
#2A- 20g C.S / 20g S. / 30g B.C. / 15g V.
#3A- 30g C.S. / 10g S. / 30g B.C. / 15g V.

After 2 hours I remixed and let them sit for 12 hours. I then remixed them a final time and applied them to the test plate.
As the bone charcoal has consistently reduced the metallic copper deposited on the surface of the steel, I decided I would do this test as long duration etches. (verses 1 hour, then clean, repeat).
The first was 7 hours & 20 minutes. I cleaned off the paste and noted the damage to the resist (vinyl & asphaltum resist)
I used an older vinyl resist sheet (orange) that had some dots on it, so I left these and just added asphaltum dots to some of the surrounding area. 
I then did a second etch for 16.5 hours. This time all of the resist, both vinyl and asphaltum was failing. I cleaned the surface and gave a lite sand to the high points with 600 grit paper. While the etch depth was good, the results were frustrating, as I did not see very much difference in the etch depth, which I was expecting given the wide range of ratios I had used.
I cut the piece in half to see if I could better see a difference in etch depth, but not really. The only noticeable thing was background coarseness, due to the large quantity of bone charcoal which is coarser than the other ingredients and of course does not dissolve in vinegar.

I'm going to do another test with the same C.S / salt ratio, but this time use different charcoal, wood and powdered Also 10g of bone charcoal, 5g and 0 bone charcoal.
 I have tried wood based charcoal and it did not seem as effective as the bone charcoal. I only tried the bone charcoal after my brother mentioned it was prized for it properties when case hardening gun parts in the 19th century. When I did some research, I found where it had been used to absorb excess copper from contaminated water and was very effective. Now, I only did one or two tests with the other charcoal, and in minor amounts. This recent test was to see if a larger percentage of the charcoal effected the aggressiveness of the etch. Until I do some other tests, I feel this question is still unanswered.

EDIT-Current formula (as of July 2021) After over 100 tests and 99% of the armour complete, the formula I'm using now with satisfactory results is:
100g fine salt (Salt flour)
100g Copper sulfate fine crystals
25g Bone charcoal
13g activated wood charcoal
Distilled water to make it a thick paste.
The reaction with the salt, will cause the material to freeze, so after mixing, you need to let the paste sit for and hour or so, and then t\remix it. NOTE: Do not make your initial mixture too wet, as after you remix it, the salt gives up some water, and the paste gets wetter.
If it is too runny, you can add charcoal to thicken. I have found 3 or 4 90 minute etches (fresh paste for each) gives you considerable depth, equivalent to late 16th C armour.

Next: The Ah Ha Moment!

Sunday, May 6, 2018

Decorating a full Greenwich garniture: Part 2

Now, as I said in the first post, these are notes from a few months back, so some are a little out of date. I only post them as a record of the process I went through to get to a solution. I have edited out some of worthless stuff and added notes to things I have since changed or discovered better solutions for.  You may skip though as much as you see fit, or do like I do and just look at the pictures. 

 Working on the computer has advantages, but because you can zoom in on the computer screen to such an extent, it is easy to loose a sense of actual size of the artwork. Elements you think are "big" turn out to be far too small. So the first test (on the right) resulted in the lines being too thin. The second test yielded a much better result.
I still have to draw the vine pattern down the center of the figure eights, as this amount of curve change using the envelope tool will distort the pattern to greatly. The result I fear, would look too "computerized". Also on this test, I added the dots with paint pen and they are too sloppy. Part of this was my not taking enough care when applying them, the other issue is the pen does not deposit enough paint in a small dot. It has been suggested that I use a tube style applicator which is likely the best tool for the job.

I received the 99% acid, so I'll make up a new batch of paste with a 50% "vinegar" and see how this affects the etch. I also opened my 20lbs bag of copper sulfate and the grains are much smaller than the sample material I had purchased from McMaster Carr. This should help in the material going into solution quicker. They also sell salt flour or popcorn salt, which is also finer grind. At some point I'll try this. I chose to buy "raw" copper sulfate and not to use "root killer" CS just in case there were other additives or some type of dilution.
I may increase the ratio of salt, in a separate test, since my first test (test 1) I had not had the recipe in front of me and I mixed the CS and salt 1 to 1 and the etch seemed a bit more aggressive.
Did some new tests. I have made a few different batches of paste with the 5% and 50% vinegar and there is not a noticeable difference. I have tried 60, 90 & 120 minutes etches, as well as a few in the 4-6 hours range. It seems multiple 60 minute sessions are better than fewer longer sessions. The issue is the copper build up on the etched surface, which needs to be cleaned off between applications of the paste. (Found a solution for this) If this copper deposit gets too thick, it seems to get under the vinyl masking easier and lift the mask off. 
I have also tried a new, thinner vinyl and a special paint masking vinyl. As suspected, the paint masking vinyl does not have aggressive enough adhesive and weeding it on the steel is unsatisfactory. This masking vinyl is very expensive and luckily the shop gave me a sample to test.
The thinner vinyl is an inexpensive product from China and works well. It's adhesive seems very good, although I suspect a name brand material may be a bit better. (turns out, maybe not) This test was 4 applications at 60 minutes each. Perhaps 3 applications at 90 minutes may also work. The dots are, I think, as small as the vinyl will tolerate, without being pulled up while weeding the background. They are about 1 mm (.040") in diameter.
I also tried a simpler vine pattern on the sides, but I don't like it.
Test 8: 

Robert MacPherson has done some research into these pastes and how they were used. He told me, one of the period descriptions he read, said that the paste was applied about the thickness of one's little finger. That seems to be what I'm getting.

I'm pretty happy with this recent test and it seems I'm back on track with a technique that works consistently. I have ordered some pen plating supplies with guidance from Mac. So when it arrives, I start plating tests. Then the bluing salt.
In the meantime, I'm finishing up the artwork for the front of the greave and will start etching the sabatons. I have been finishing the figure eight/ lighting bolt design and testing different mixtures of paste and different etch duration's.

1: Ratio- 1 parts salt / 2 parts Copper Sulfate / 1/2 part Vinegar. (I have a newer version of this)
Mix well and add more vinegar as needed when solids start to dissolve.
As the solids dissolve, the mixture changes color from aqua green to lime green and gets creamier. To aid in liquefying the solids, I ordered Copper Sulfate on Amazon that was a finer grind than the "root killer". I have been using regular table salt, but I think if you use popcorn salt or "salt flour", (finer grinds of salt) this may be beneficial. I did a side by side test with too pastes, one with table vinegar, 5% and the other with 50% Vinegar. There seemed to be little difference in the etch depth over the same amount of time. However, the 50% paste did more damage too the vinyl material, causing more tiny elements (dots) to come off. I also tried 1 part CS to 1 part salt, but this did not seem to increase the etch much, if at all. Temperature; My first tests were during some hotter days here in LA, so I though this may be affecting the etch depth. I tried heating the plate during the etching with a light bulb and just at the cooler room temp. (70 f). I observed no significant effect.

2: Fresh etching paste seems to be key. (Maybe not)
I'm not 100% sure on this (I'm testing fresh verses old material now), but recently I had a number of tests that were not as deep as my early tests. When I compared them, in date order, it seems the older the paste, the less aggressive it became. I was getting frustrated since it seemed, as I advanced in developing the artwork and masking techniques, I was going backwards in the effectiveness of the etching. It does seem like 4 to 5 day old paste is the culprit. If there are any chemists out there, I'd be curious to hear why this may be.

3: Etch times 1 hour to 3 hours each application.
In my first tests, I had been etching 60 to 90 minutes per application. Being careful not to destroy the resist during the cleaning. The etch process leaves a copper build up on the surface. This layer seems to either get under, or stick to the vinyl masking. If it gets too heavy, it pulls more vinyl off.
I have found 3 to 4 applications at 90 minutes each worked very well. However, last night, I left one test plate overnight for the 4th and last application of paste, and it came out perfect. So I'm testing two & three, 3 hour applications to see if I can leave it this long and still preserve the masking. I think the paste can be left on until it all turns brown / black. Over 90 minutes, only about have the material has blackened. The uppermost surface is still green. Mac mentioned a period source saying the paste was applied at a pinky fingers thickness. I believe this may be to facilitate longer etch times, since once the paste is black it seems no longer effective. The most recent test over night (about 7 hours) most of the paste was black and much of the masking lifted during surface cleaning.

EDIT-Current formula (as of July 2021) After over 100 tests and 99% of the armour complete, the formula I'm using now with satisfactory results is:
100g fine salt (Salt flour)
100g Copper sulfate fine crystals
25g Bone charcoal
13g activated wood charcoal
Distilled water to make it a thick paste.
The reaction with the salt, will cause the material to freeze, so after mixing, you need to let the paste sit for and hour or so, and then t\remix it. NOTE: Do not make your initial mixture too wet, as after you remix it, the salt gives up some water, and the paste gets wetter.
If it is too runny, you can add charcoal to thicken. I have found 3 or 4 90 minute etches (fresh paste for each) gives you considerable depth, equivalent to late 16th C armour.

Masking, Better vinyl works better and lasts longer. I have the cutter now effectively cutting background dots at less than a mm and adhering to the metal sufficiently to arrive at an acceptable etch depth. The new vinyl can be mostly weeded on the backing paper, which is much faster than pealing the excess material off the metal. It's only the areas with the dots that have to be removed from the steel now. Because if this is done on the backing paper very few of the dots stay.
I still have not picked up the name brand vinyl sample from my graphics guy, but this generic material seems to work pretty well. If you get the cutting knife depth dialed in along with the cutting pressure, the machine cuts the vinyl without lifting up too many dots.
Still do not have an effective paint type mask that lasts. Testors model paint, fingernail polish, enamel spray paint, paint pens, sharpies, work for perhaps one etch application, but come off fairly easily. The fingernail polish is the most effective of the materials I've tried. I have ordered some asphaltum to try.

I'm sure if I had the drawing skills, this would be a faster process with the proper masking medium and a pen or brush. But I'm forced to use the tools I have the skills with when faced with this much artwork.

Here is the latest test: 3 applications of fresh paste for 90 minutes each and a 4th application for 7 hours. (You will notice a misalignment on this vinyl mask cut)

 The etch depth is the best I have gotten so far. It's about .008" deep. This is now looking like the etch depth of the real armour. 
I had considered bees wax as a way to get specific dots. I'm not sure the best way to apply them. It may be as easy as a large straight pin.
 For the test, I used fresh, 1 day old and 2 or 3 day old. They were nearly a factor better than each other, the newer the paste cutting at least 10 times the depth of the 3 day old paste.

Here is a close up of the real armour, it seems I'm getting close.

I also received the pen plating supplies and at first I thought my rectifier was not working, but it was just that it had been sitting so long (10 years probably) that the variable resistor coil was corroded and needed cleaning. So I plated a couple of the earlier test etchings.
I also got out the bluing salts.
It's hard to see in the photo, but the blue is electric when the light hits it just right. The gold also yellows considerably with the 600 degree heat. Again, it is hard to tell in the images, but I went over one band of gold with fresh plating to bring it back to a lighter, less orange gold.

Controlling the color on the big pieces will be difficult, but on this first try, one piece went through blue, to a grey color. The piece pictured above was a shorter duration and the salt had cooled down some. It turns out the salt wants to be at 550 f, not 650f as suggested. So if I find the sweet spot as far as temperature goes, the color may be easier to control.

Today was cutting masks and adapting them to the greave. I have to start with the main pattern on the front plate, so I can cut sections to fit the lames while matching the main pattern. I still need to add the wider vine boarder on the sides and mask the large area on the main plates.

I have done about 40 different tests, using a combination of ingredients and ingredient ratios, (Copper sulfate, Copper acetate) as well as different etch times and number of etchings. I have also practiced ways to repair the vinyl resist with asphaltum resist, since with multiple application of etching paste, the material can start to lift, or at a minimum, I loose dots. The best applicator for the I have found for the asphaltum resist is a "Henna" applicator bottle, available as a kit from Amazon.

The batches I have been mixing are: (by volume) 
(I have since developed a better recipe)
3 parts fine salt (I bought a large 196oz. container from "Smart & Final" a local restaurant supply)
6 parts Copper Sulfate This is a much finer grind than the "weed killer"                                                    variety.
                                               1 to 1.5 parts 7.5% Vinegar

The trick is to mix the salt and copper sulfate together, then add the vinegar and mix. It will seem like too little vinegar, but after mixing, let the mixture sit for 1 to 11/2 hours and re-mix. There is water trapped in the salt (and possibly the CS) and as the solids dissolve the extra water is released and the mixture changes from a "wet sand" consistency to a smooth paste. This is important if you want to make it stick to a vertical surface. Too much vinegar and the paste will get runny after it sits for awhile.
Here is the first section of the armour to get etched. It's the front of the left greave with the ankle lames. I had etched this piece earlier, but the copper buildup from the etching process was difficult to remove and I was concerned about damaging the vinyl resist so I let the paste sit longer and this did not work well. As a result, I had to very carefully sand down the etched areas and re-polish. Thankfully Mac and Jeff planish very well before sanding, thus the already thin metal was consistent in thickness and I didn't run into thin spots while sanding. (Something that cost me two greaves when I had made them for my 1330's kit. :x )
Here is a close up of the center of the greave. This was 4 applications of paste at 60 to 70 minutes each. You can see some of the "repaired" dots. I may abandon the dots in the vinyl and just add them with the asphaltum resist straight away.
I would like it a little deeper, but the vinyl is so fine, it begins to lift on the 3rd application. Longer times seem to be less effective. 60 to 90 minutes gives a good etch and still allows the copper deposit to be removed easily. On the larger pieces, where the pattern is larger, I can probably etch 5 or 6 times, to get it deeper. In the close up images I have of the original armour, it looks like the breast & back are etched deeper. I have fully etched to front of the left greave and have most of the back masked.

 You can see the real armours lower leg on the screen and if you look close, you'll notice the negative space on the outsides of the figure 8 pattern are a little larger on mine. This is something I'll correct on the rest of the armour as I work my way up, but I will make the right greave match this one. Now, back to applying the vinyl to the rest of the greave & sabaton pieces.
I have taken to putting the background dots on with the asphaltum resist, as this makes them more durable and makes cutting and weeding the vinyl easier. I am also reinforcing thin areas and loose ends of the vinyl masking because these are the areas that are the most vulnerable during cleaning between paste applications.  This is the back plate of the greave and the different tools I'm using to apply the resist.  Now that I have the system down, I should be able to get the right greave done in 2 or 3 days, (Yeah, Right!) unless I get interrupted. (Like I may have to go to South Africa next week)

Next: Viewing the Master's work....Well, I thought it looked good....