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Originally Posted by Linda Brandon
Ah, Sharon. Just the brain I need to pick today... .
I have two big panels of 1/4" black Sintra sitting in the corner of my studio. My plan is to use them as a backing for my charcoal/Nupastel drawings on sanded ABS. The black Sintra is around 6" larger on all sides than the ABS, so it will act as a "mat" for the drawing. I've sprayed the drawing with archival spray varnish. The object of this whole enterprise is to come up with something that doesn't have to be glassed over, which is the big drawback about doing large drawings. Have you ever tried spray varnishing your pastels?
Questions:
1. have you ever glued ABS to Sintra? what do you think, contact cement? I plan to give the Sintra a light sanding first, mostly to knock off slight dings and scratches in my pieces.
2. I'm thinking of putting a piece of wood on the back to put screw eyes in to hang this thing. Again: contact cement, do you think?
3. I thought these plastics only absorbed UVA if they were sanded first.
4. An engineer told me that Sintra is a foam and more susceptable to UVA penetration that regular ABS. Is this wrong?
I'm now going to your other post to read about gessoing Sintra. But you wouldn't need to do this unless you wanted more tooth on your surface, right?
I've been fiddling with these problems for months. Since the drawings aren't commissions I've had to put them on the back burner when I get a lot of paying work through the door.
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Linda, Linda Linda!
This is what I have found out so far, after consulting, my plastic guy, the technical support people at Alusuisse ( the manufacturer of Sintra), my husband, a scientist with an engineering backround and his colleague ( specializing in materials) in the engineering department of the University of RI.
A:ABS plastic warps and absorbs moisture. My plastic guy says do not use it.
B: Check with Alusuisse about compatible glues. I had to send away for special glue in California, and was fortunate enough to have a very good cabinet maker make the panels for me. He said the glue fumes were so powerful., they were physcedelic and worse, not to use at home!
C: Alusuisse has a website, you can download information, search under Sintra (PVC).
D: I braced the Sintra panels with 3/4" Sintra. I bought a whole 3/4" panel and had it cut into 2" strips, by the distibutor. Distributors will most often cut the panels to size for you and deliver them to you or
someone else.
E: The company considers Sintra as archival. It is expanded PVC. PVC is used in exterior shingles and underground plumbing, as such it is quite stable. It is not prone to warping and does not absorb moisture like ABS. It is subject to embrittlement when exposed to UVA rays. It should be coated with a paint, sanded lighly first with a 320 or 360 grit paper.
F: You can spray pastels heavily enough to make them resistant to smearing, but many colors especially blue become too dark, almost black. It works well on sanguine drawings however. You might want to talk to Mike Townsend at
www.goldenpaints.com. He is very knowledgeable about spraying pastels and probably knows some new wrinkles I haven't heard of . As a matter of fact they have come out with a new varnish, that just walked in my door today. I am excited to try it. They get a lot of requests for ideas about permanently fixing pastels. If your drawings are limited in color his procedure would work for you. It is worth a try.
G: A simpler way would be to have good paper mounted to Gatorboard, do your drawing, then spray away. I do not know the advantage of using ABS plastic. What you have proposed is heavy, cumbersome and probably expensive.
Hope this helps!