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A Bramblebush Workroom Project
Repousse`/Chasing
A compendium of miscellaneous information
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Page 03
Jan. 6, 1999 -Â .... Pitch...anybody want to tell us how to use this stuff? I made up my own ugly > mix and it's none too pleasant to remove from the work since it's essentially > a mix of roofing tar and plaster although it really works just fine. And it's > cheap to make up. What do others use and why? How do you get rid of this > stuff after you did your embossing or chasing? I have a piece still stuck in > a pitch block and figure I'll have to heat the piece to remove it then clean > it up afterward with mineral spirits or burn it off but then I'll anneal the > work which I may not want to do.
I was thinking the same thing about the nasty goo problem that pitch poses. I was wondering if anyone had tried using a really soft ureathane bladder that had lots of small holes in it. This bladder could be in any size/shape and probably should be about about at least 1" thick. Underneath it would be a support table also with small holes that would line up with the bladders holes. Underneath the support table would be a vacuum tight manifold that would encompass all of the holes.
Hook up a vacuum pump to the manifold, and any metal laying on the almost gooey urethane surface would be sucked down tight. The urethane would give just like the pitch does, but clean-up would be a no fuss no muss deal, with quite a long life for the ureathane bladder. Anybody ever hear of a pitch substitute method, something along the lines that I just described?
Wray Schelin
Jan. 6, 1999 - Okay, I'll pick up on the pitch. Getting VERY basic, pitch is the material that supports one side of the metal while you are working on the other.
Commercial or home made asphalt or pine sap based pitches have always been a problem for me in that they are slow to soften with heat, and when working on a panel larger than your hand, you need a large amount.
In the past I have used both tar based and pine based pitches. They were much easier to clean off the back if you put a light coat of veg. oil on the copper before anchoring down. Again the size of my work was a problem, quickly outgrowing a 9" round cake pan and a 9"x12" pan.
I had a 5lb brick of Plasteline that resisted nicely when whacked with a chasing hammer, but the oil in it made it more sticky than it had to be to hold the copper, and cleaning was slower than I liked. I kneaded ground cornmeal into it to soak up some of the oil, and add "toughness". Worked like a charm. Now I back up only the area that I am working, not the whole piece, and there is no torch needed to heat the backup material. On a cold morning when the plasteline is hard, an orange sized ball becomes pliable enough in 10 seconds in the microwave. Just soften and press into the area to be worked. As it cools, it hardens. I work on a piece of 1/2" rubber conveyer belt. The plasteline is easy to roll and flatten to any shape, easy to push into raised areas, and it peels off the surface of the copper leaving practically nothing behind. No solvents, no burning necessary. I generally use an inch or two in thickness behind the area I am working.
I have no idea how much cornmeal I added to 1 lb of plasteline. Just kept adding and kneading till it was thick and not sticky. This method works well for the copper sheet that I use, don't know how well it would work on other metals. I am going to try it under some 20ga mild steel soon. (High relief chasing) So far I have only used a pine tar pitch under the steel, and it works well, except for having to remove the pitch from the material to reanneal.
Hopefully I have covered the "plasteline angle". It is available in most art supply stores, and for blacksmiths, it is a handy material for testing new "wizard head" and animal head punches and chisels used for carving steel. Any questions?
Chris Worsley
Jan. 6, 1999 -....Do not compromise by substituting the cast-iron pitch bowl with another > > one, lighter in weight just because it may be cheeper. For a quality work > > and for a convenience you need a heavy cast-iron bowl on a rubber ring,
Yes ... or turn one from heavy wood!
Turn a 2/3 sphere from some real dense solid wood and also turn out a 1" level-bottomed depression in the flat top. Here's where the pitch goes. So you only need a small am of it! Easy to remove and replace if someone tells you about a better pitch. Sit it (like the cast iron bowl) on a rubber lawnmower tyre for a rotatable base.
Wood is is what Marion Marshall (Aust) uses. Got the idea from Japan. Runs 2 at a time as there is often a wait while it cools to the working temp. Â She has two bowls at least going at once, so that while one's cooling down from having been heated up to pop the metal down on it, she works one that's ready.
Brian Adam
Jan. 6, 1999 - Â I do not know how heavy the stainless steel salad bowl is. My wife uses a plastic one. In any rate probably not as heavy as the cast -- iron bowl. I agree with Brian and the others who suggest different materials and makes. But if we think time wise it may really be cheaper to just pick up the phone and order the cast -- iron bowl from a supplier. It only costs 30+ Dollars and we will save a lot of time (looking for something in the scrap yard, cutting and cleaning the rusty steel or having somebody turn a wooden one on a lathe)
One of my students brought several good size bowls from a scrap yard (something the farmers use to give water to the caws) He said he'd spent a good amount of time and several small discs cutting the unnessesary parts and cleaning.
Anyway - for chasing you can also use an old cast -- iron frying pan or just make a wooden frame with a plywood on the bottom and fill it up with pitch. Â Only make sure you are insured against fire. You can also spread pitch on a wooden bord and mount the metal on it.
Valentin Yotkov
Jan. 6, 1999 - In terms of the weight of the bowl-- in my experience, this is not so crucial in jewelry work. Since I am often doing high relief in impossible tiny areas on ridiculously heavy metal-- for instance a running horse on a 3/4 x 1/2" plate of .040 18k--the lightness of my setup is a great advantage. I can hang my triangle frame at 45 degree angle off of a bench stake, and still rotate my bowl. You could not do this with the rubber ring, it will distort, and the weight of the bowl will make quite an impression on your toe. The shiftyness of my setup is a small flaw, but easily controlled. Probably black tape on the upper surface of the jig would do it.
Valentin, you started off like an art teacher, saying it must be just this way or that way. Now you have revealed that you have an unorthodox side, and know a few tricks besides what's in the books. For me, the combination of classic technique and mad improvisation will always have a more satisfying result than merely going by the book, or slashing in wildly. There are a few chasers around whose technique frightens me, they are so good, but their work bores me, it's even silly sometimes.
Robin the Hammer
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