This is the weeded vinyl mask I will use as the sandblast and acid etching mask.
I registered the glass over the mask and blocked in the area to be glue chipped with asphaltum varnish. The open window will be clear glass for the acid etching.
The mask is then applied over the dry asphaltum.
The acid/mica mixture is applied over the mask and left on for 30 minutes. Be aware of all of the proper handling proceedures when using HF.
Resulting acid etch texture.
This sign is roughly 24" x 48", or 8 square feet. Discounting the "La Azora" panel, border, other text and elements, I figured it to need about 6 square feet worth of glue mixed up. It wouldn't be so nice to run shy, so I mixed up 7 square feet worth. I mixed up 21 dry ounces by volume of glue, with 31.5 ounces of water into the glue pot and let it soak for about an hour. The picture above is after it has soaked. It looks kind of like oatmeal. The glue is then heated for about 2 hours. I like it streaming hot when applied.
I masked over the acid etched portion, then sandblasted off the exposed asphaltum, ensuring the glass was also sufficeintly etched.
The sandblast mask is removed and the piece is leveled. It is rather cold in the shop today, so I am warming the glass with my propane heater.
The prepared glue is put into a squeeze bottle, then flowed over the sandblast area. Typically I run the tip of the bottle about 1/8" away from the edge of the asphaltum and allow it to flow up to that edge. If a small amount of the glue goes over onto the asphaltum, the glue will pull up the asphaltum and should retain a clean sharp edge.
Here's the panel with the glue flowed out over it.
The glue self levels as it's flowed up to the asphaltum. Now I will leave it to dry until the glue is transparent.
Here's the glue after it had been allowed to dry overnight. The glue becomes hard and translucent.
It was a nice day out today, so I put it out in the sun to chip. I layed the glass on a board that is covered in black carpet. The surface of the carpet was 90 degrees in the sun. The glue proceeded to chip off. It left a bit more of the sandblasted texture than I'm used to seeing. Pat Mackle thinks that perhaps the glue hadn't made a strong enough bond to the glass. I will inspect the resulting chip, and if I don't like it, I can always double chip it. I've had perfect results doing it this exact same way, so sometimes it's a bit baffling as to why it doesn't act the same. I figured I could save a couple bucks by putting it out in the sun as opposed to heating my glue chipping closet, but perhaps I would've got better results. I'm going to do some tests, and I'll report back.
Here's the finished chipping. ...I ain't lookin' over my shoulder the rest of my days unhappy with those large areas of sandblast, so I think I'll double chip it.
I inspected the asphaltum varnish and touched up areas as required with a brush. Then, I reflowed glue over all the previously chipped area, just as before. I allowed it to dry to a clear, hard state.
I slapped together a booth to chip it in. I put the sign on a cart with my Coleman catalytic heater going underneath it.
I sealed the booth up. It's currently 45 degrees F inside at 8:20 this morning. I'll keep ya posted on the results!
In one hour the temperature is up to 65 degrees and it's starting to chip at the edges of the glue.
The booth reached 85 degrees and the piece started chipping nicely, it has now stopped chipping half way through. I don't really know why that is. Perhaps Pat could shed some insight on why the glue stops chipping while remaining in the same environment. Twill...you out there?
Here's how far it got before it stalled out.
I let it ride overnight, and most of it chipped off. I encouraged the rest of it to come off with a little temperature shock treatment and a few stabs with my exacto knife. Double chipping usually results in a finer chip pattern, removing most of the sandblast texture.
Here's the single chip compared to the resulting double chip.
...a little closer...
Next, I cover it with paper towels and wet it down with water to soften the remaining glue. I'll the gently scrape it off with a razor blade.
Although the 1st panel looks very elegant double chipped, I still was after a better single chip. So I decided to do another one. Once you've chipped it twice, it's easy to make it three. I've done a few things differently. The first one I sandblasted with 100 mesh sand. This one I decided to see what my 220 aluminum oxide texture would produce. It is substantially finer than the sand. I flowed the glue over it just as before, with the squeeze bottle.
Another thing I did, which I didn't do on the first, is to put a small cut in the glue at every sharp corner of the design. This is done at the gelled stage. I believe, causes the glue to pull away from the corner, leaving it sharp. (This photo was taken after the glue was dry.) I put the piece in the booth I constructed with a fan running inside. I allowed the glue to dry for about 46 hours. It turned to the transparent, hard state that you want prior to inducing it to chip.
I pulled the piece out of the booth and preheated the booth to about 100 degrees. I fired up the catalytic heater and put it back in as before. ...we'll see what we get here soon....
Here it is after about 4 hours. It's starting to chip nicely. The booth is stabilizing at about 85 degrees. The shop air temperature is 50 degrees. It's also been raining quite a bit. I need to get a good humidity gauge, so I can report the humidity...on the next one.
I watched it chip while I ate my lunch. Forceful chips were flying off about every 15 seconds, yielding a very beautiful pattern.
Now by 2:00PM, it's all chipped off, except for some very minor areas. It took 6 hours for this panel to chip. Once it started, it happened fast.
Here is the resulting chip on the second panel. An interesting thing, that when it started to chip, it was yielding some very interesting chip patterns. Interesting fan and sea shell shapes. But later on in the process, it changed to what I call a "coffee bean" chip pattern. I'm not really sure why the pattern changed half way through.
Here's the interesting swirling chips.
And here is where it turned into coffee beans. Which can only mean one thing...do another one...guess I'm sick...but, once you've done 2, it's easy to make it 3!
I acid etched this 3rd panel same as before, but used my powdered grade mica. I sift the mica flakes into 4 grades, this being the finest. It yields a very fine texture.
On this one, I'm going to do the "double cut" method. This method doesn't employ the application of asphaltum varnish. The sandblast stencil is put directly onto the clear glass, and sandblasted. Glue will be flowed over the entire panel, and once gelled, the glue will be cut around the stencil and removed.
After it has been sandblasted, a tape dam is created around the perimeter, to keep the glue from slopping off the edge of the glass. The piece is then leveled.
I preheated the glass in the chipping cabinet to about 100 degrees. Pouring the glue on warmed glass increases the open time of the glue, allowing it to be spread and return to an even level coat. Pouring the glue on cold glass will cause the glue to gel up quickly and not re-level when spread. The molten glue is then flowed out over the entire piece (notice the steam rising from the glue). I use 6 fluid ounces of glue for every square foot of glass. I will now let it set up to a consistancy where it can be cut.
Here, I've cut the glue with my x-acto knife following the edge of the vinyl stencil, once completely encircled, the piece of vinyl with the glue on it is carefully removed. This process is a bit tedious, but you do get to skip the step of cleaning off the asphaltum varnish. It's now left to dry as before, until the glue becomes hard and transparent.
I rolled it into my make-shift chipping booth, with the heater on real low, and the fan on low to circulate the air. I figured it would be dry by morning and I could crank it up to start it chipping. Well, much to my surprize, when I came in this morning at 8 AM, it was already 2/3 chipped! The heater stabilized at about 60 degrees. It's yielding a nice chip pattern (photo to follow when completed). Uh-oh, you know what happens when things don't go quite as planned? You guessed it....SWM
I took these down to Roderick's House of Style, figured we'd silver 'em up. First thing Rod did was clean the glass with a wash of Muriatic acid.
Next, he gave it a scrub of Cerium Oxide, then rinsed it off really well.
Then we applied the silvering mask. This mask will leave the letter centers open, and leave a silver bright line around them.
Rod then tinned the glass, followed by a good rinse.
Rod sprays the silver solution, rather than pouring.
We decided to give them some antiqueing, to make them look old rather than new.
Here's what happens if you let it slip out of your hand....#@!*%#
Guess I will have to do another.....
Here's Rod's antiqued version from the front.
The center panel is bright lined by hand, then the rest is blocked in with asphaltum varnish. Rod peeled out the mask and made the letter centers black (with the asphaltum). If the lettering was to be a color, you'd peel the mask after the asphaltum.
Here it is backed up.
The silver in the center panel is removed with silver strip. This is how it now appears from the front.
Rod then water gilded the etched La Aroza copy and backed it up by hand, he then painted the panel. Here it is finished! Good job Rod!
I finally got back to working on mine. The vinyl mask for the letter centers was reapplied, this time I masked out the center panel, so it won't have to be brightlined by hand.
I poured the siver solution rather than spraying it. Again, I gave it a light antiqueing.
I backed up the silvering with asphaltum varnish. Rather than weed out the vinyl then back it up, having the letters be the color of the asphaltum, I'll weed them out afterward and paint them a color.
Here it is from the front after the vinyl has been weeded. This process leaves a nice clean silver brightline around all the letters. I like to pull the vinyl after the asphaltum sets up, but isn't completely dry. If you wait til it's completely dry, it shatters off of the vinyl and makes a big mess. When it's still a bit gummy it stays stuck to the vinyl.
The "La Azora" text was cleaned and water gilded with 23K gold leaf. After the first gild had dried and was burnished, the minor holidays were patched.
The gild was then brightlined by hand following the edge of the acid etched letters.
The outline was then filled in.
Once dry, the excess gold was cleaned off using the gilders brush. It was inspected from the front and trimmed up as required.
A black outline and drop shadow were applied to the letters.
Next, the glass was cleaned and a given a coat of spray shellac. This keeps the asphaltum from reactivating when a solvent based paint is applied over it. A transparent black shade was then applied to both vertical sides of the panel.
Once dry, the entire panel was blocked in with a solid color of green japan.
Next, the remaining text was blocked in with color. The upper and lower text were blended.
Here it is from the front. Now to make a frame.
Denver Chapter of the Letterheads