Saturday, May 12, 2018

Decorating a full Greenwich garnature: 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.

Next: The Ah Ha Moment!

Sunday, May 6, 2018

Decorating a full Greenwich garnature: 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.

Notes:
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.

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....

Monday, April 30, 2018

Decorating a full Greenwich garnature. (Late 16th C. Armour)


A few years ago I posted a bit about this armour, but I thought I would start a specific thread on it, now that I'm working on it again (I took time off the restore my dad's race car for it's 40th anniversary)
It is a copy of a Greenwich armour with medium decoration. Most closely styled after the armour of Sir Thomas Sackville, Lord Buckhurst. The "Buckhurst" armour that is currently in the Wallace collection. (A62)

There is a nearly identical armour at the Metropolitan museum in NYC,

Also a half armour in Art institute of Chicago. (this was recently featured in the NOVA special)

I commissioned Robert MacPherson (Mac) in 1999? for this armour, but during it's construction Mac injured his elbow. So it sat for awhile. About 3 or 4 years ago I approached Jeff Wasson about finishing it. At the time, approximately 70% of the main suit was complete, but I really wanted a full garniture so there was quite a few pieces left to make.
The suit is being made from 1050 and will be fully heat-treated, acid etched and either gold plated or fire-gilded, then salt blued.
It will consist of: the full suit, with burgonet and falling buff, like the two complete extant suits. In addition, there will be a close helm with interchangeable field & joust visors, reinforce breast, grand guard, couter, manifar, & Locking gauntlet.
As of now, all the pieces are formed and about 70% are ready for heat-treat. Last year, Jeff has delivered the the cuisses, greaves & gauntlets, which I have already heat- treated.
I am currently working on the etching process. Due to my lack of drawing skill, and the massive amount of etching on this suit, I decided to use a computer to generate the artwork. To start, I trace the etched patterns from closeup images of the extant armour and then use a plotter/cutter to cut vinyls as a mask/ resist. This is working very well and I can maintain the very fine hand drawn look, but pretty quickly make the hundreds of inches I'll need for all the boarders. In some places, I have made masking tape patterns of the sunken boarders where the patterns need to match specific curves or tapers, I scanned those patterns and using Corel Draw have adjusted the artwork accordingly.
For the etching, I'm using the same etch paste recipe that was used on the replica breast & back that Jeff built for the NOVA special, copper sulfate, salt & vinegar. This recipe I understand was derived from a period source and translated into modern chemicals by a scholar who specializes in medieval chemistry. Perhaps Jeff will chime in with additional info here.

To create the artwork, I am using a Microsoft "Surface" so I can draw on the screen over hi-res images of the real armour. I figured, for me, this would be the best way to capture the correct style. I'm creating the artwork in Corel Draw, a program I've been using for nearly 30 years. (I highly recommend it) Then I'm using a "Zing Orbit" desktop vinyl cutter to cut the masks.


I had some old vinyl left over from "Power Rangers" , (Pink-PR) but it was too hard to "weed" (remove unwanted vinyl after cutting) so I bought some from Michel's art supply and this is working very well. I'm going to order some higher quality stuff and try that, but at the moment I have been tackling the etch process and how well the artwork translate to the final etched metal. I am very impressed at how small this cutter can cut and it's accuracy. Here is the cut mask on the metal:
I'm also using an oil-based paint pen for dots. This still needs some experimenting.



So, as I said, I'm using an etch paste made of 2 parts - Copper Sulfate, 1 part -Salt, and enough Vinegar to make a paste.


When I did the first test, I was using the old vinyl and it was easier to "weed" the "vine" part and leave the background. So I used the vinyl as a paint mask and used Krylon spray paint as the etch resist. When mixing the etching compound, I just wet the "sand" textured salt and CS with enough vinegar to make a grainy paste. I used 2 applications of paste for 60 minutes each. Test one:





The graininess is an issue as the real suits etch has a nice smooth background, no real texture. Because the background was so "pebbly" I figured I would need to grind the salt and CS finer. I had a nice mortar & pestle from Historical Glassworks so I gave that a try. After considerable work, the mixture was not significantly finer. But, while at Micheal's for the new vinyl, I picked up some "Armor etch" acid paste. That's gotta work Right?! Here is that test. You can see the graininess of the green past, the "armor etch" is the white material.


This test was over an all paint pen artwork and the Armor Etch was not very effective. So I have relabeled the bottle "Not, Armor Etch" This test was not useful as the paint had not dried sufficiently and was mostly obliterated while washing off the first application of paste. But I did notice how much crisper the etch was where I had masked the plate with a piece of vinyl. It also turned out, the new vinyl was easy to weed once the cut vinyl had been adhered to the metals surface. So the next test, with the finer ground material, the paste was applied over the cut vinyl. Test two:

I also thought the etch needed to be almost twice as deep, since in the close up images of the Buckhurst, you could see a significant shadow caused by the etch depth. My etching didn't seem to be nearly this deep. So, I'd try 2 things; First, leave the paste on much longer. Second, get some stronger vinegar. Household vinegar is 5% acetic acid and I found 30% concentrate on Amazon, but I also found some 99% acetic acid, so I ordered that. Now as the strength goes up, so does the dangers with acid, so my plan is to cut it to 50% as soon as I get it.
I also did another test, this time leaving the second application of paste overnight. It cut deeper, but the texture got worse. Test Three:


This was going in the right direction, but I had solve this textured background issue. Chemistry was not a subject I was excited about in High school, so I had to look up if water was a solvent for Copper Sulfate. It is of course, and I realized my error; I needed to fully dissolve the crystals into solution before using them. I mixed the salt and CS with distilled water and after 5 minutes of mixing, I had a creamy green paste. I had also distilled some vinegar by boiling it on the stove, in an attempt to increase the strength. I added this to my paste, so, because of the distilled water added to the mixture, I figure I was likely back to 5%+ concentration. This worked very well. No serious texture and it was starting to look like the real thing. Test Four:




In the closeup, you can see how fine a line the vinyl will "protect" from the etching paste. I may try heating the paste a little.

Since the water dissolves the copper sulfate fairly quickly while mixing, I found I could make up a batch of the paste and let is sit over night and the crystals would dissolve into a smooth paste. I store it in a glass jar, but I need to find something with a non metallic top for long term storage. Here is the paste:

I had been using a tongue depressor to apply the paste, but this batch was a little thin, so I tried a brush. It turns dark brown upon contact with the steel. I added another batch of salt & CS to thicken the paste.

This works well on these small areas, but I really need to see if I can control the etch on larger areas. 

Next: Creating artwork for the center greave and testing the bigger patterns.