Sandable coating/filling for plastic

Stuart R

Member
You know that corrugated plastic board that real estate agents use for yard signs? Is anyone aware of a coating, whether it's some modern equivalent to the old Sculpt or Coat, or a secret scenic dope recipe, that would stick to that kind of surface, dry hard, and be sandable? Please don't say "just use plywood instead," because someone has already put a ton of time into working with the plastic, and now it's time to finish it. We could lightly sand the plastic first if that would help Any ideas? Thanks.
 
You know that corrugated plastic board that real estate agents use for yard signs? Is anyone aware of a coating, whether it's some modern equivalent to the old Sculpt or Coat, or a secret scenic dope recipe, that would stick to that kind of surface, dry hard, and be sandable? Please don't say "just use plywood instead," because someone has already put a ton of time into working with the plastic, and now it's time to finish it. We could lightly sand the plastic first if that would help Any ideas? Thanks.
Calling @Van
Toodleoo!
Ron Hebbad
 
Stuart, did you see this in the WIKI?
 
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You know that corrugated plastic board that real estate agents use for yard signs? Is anyone aware of a coating, whether it's some modern equivalent to the old Sculpt or Coat, or a secret scenic dope recipe, that would stick to that kind of surface, dry hard, and be sandable? Please don't say "just use plywood instead," because someone has already put a ton of time into working with the plastic, and now it's time to finish it. We could lightly sand the plastic first if that would help Any ideas? Thanks.
I'm not sure this is a good application for VSSSD unless you're able to leave a pretty rough surface from sanding. It sticks to some plastics but you might want to test first. You might want to prep the surface with a Krylon Fusion primer. It chemically bonds to the plastic You might need to go to Bondo. for the sandability though.

What texture/Fill are you going for?
 
Coroplast (common brand name of this material) paints OK, although probably more susceptible to scratching, so it's possible the normal range of coatings would work OK if durability isn't a great concern. Worth a test. Agree with Van that a plastic primer would help. Another good test might be to prime in 3M 30NF "green glue" contact adhesive.
 
Bondo would certainly do it, but any flexing and it would certainly all start cracking off.

Theres got to be a Smooth-On product ideal for this, but im no smooth-on expert. Maybe Epsilon? We use it at work to put a hard shell on 3D printed items.
 
I'm not sure this is a good application for VSSSD unless you're able to leave a pretty rough surface from sanding. It sticks to some plastics but you might want to test first. You might want to prep the surface with a Krylon Fusion primer. It chemically bonds to the plastic You might need to go to Bondo. for the sandability though.

What texture/Fill are you going for?
Hoping for a smooth texture. I'm thinking Bondo might crack.
 
In a different vein is a moldable rubber-like substance called Sugru. It's totally awesome, sticks to just about anything, and if you install it correctly and smooth it with water you can get a very nice flush surface. It comes in about a dozen colors and can be mixed to make custom colors. It doesn't sand well though.

Hope this helps -
 
When I need a paintable hard coat for most materials I use Styrospray 1000. It is an isocyanate based 2 part coating that can be brushed on. I have used it on foam, wood, and PVC. There are videos on YouTube where they coat balloons and it gives the stability. I am not an industrial hygienist or safety specialist in any way. You should always read the MSDS for the products you use. At the first company where I used this product the mere fact that we were using isocyanates warranted an inspection by OSHA. They did air sampling and monitoring and determined that our precautions were adequate. I only give this warning as a heads up. If you want to get a more in depth Monona Rossol has written a couple of books that directly address hazards and protection that are written specifically for the Theatre and Events industry.
 

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