Flat clear coating clear plastic?

[neil_w]

Would there be any problem applying flat clear coat to clear plastic? Would the end result be fully transparent, or would the flat coat make it a bit cloudy? If so how much?

Normally I would just try it and see but it'll be at least a few days before I can get to it and I'm desperately curious. Has anyone else ever tried this?

 

[rharshberger]

Use a test piece, the solvents in the clear or some other component in the clear may attack the plastic.

 

[neil_w]

Use a test piece, the solvents in the clear or some other component in the clear may attack the plastic.

Ooh, had forgotten about that aspect. Will test at first opportunity.

 

[neil_w]

It occurs to me that this is a bad idea even if it works. Given that flat finishes tend to hold onto dirt, a clear section is probably the last place you would want it. I'll just let it stay naturally glossy (actually extra glossy, with coats of Future).

 

[Nytrunner]

Tape off the cornea for all painting (assuming I know what this is about....)

 

[neil_w]

Tape off the cornea for all painting (assuming I know what this is about....)

You do.

I have three options:
1) Flat coat and then assemble. This will flat coat the interior bits as well.
2) Assemble and then flat-coat. This will flat coat the cornea.
3) Assemble, mask, and then flat coat. This will leave the cornea gloss.

In addition to laziness (which drives most of my decisions), I was wondering if flat-coating the cornea was actually a *feature*, not a bug. But I think the "gets dirty" aspect makes it a bug, and therefore I shall choose #1 or #3.

 

[Nytrunner]

I'm in agreement about the paint etching or messing with the dome also.

If you go 1, you'll have to mask where the dome will adhere, so you might as well just mask off the whole interior face.
3 may be simplest since you just have to tape over the dome and trim to the interface.

 

[neil_w]

I lean towards #3 as well. BTW, there's already some paint where the cornea will glue on; it's virtually impossible to do that fine of a masking job. The epoxy joint to the painted surface will have to be good enough; since there's very little stress on that joint I suspect it will work OK. There are also still some open pores there which should help.

 

[Sooner Boomer]

You're wanting to do something like...

latch11

• Sooner Boomer
• May 14, 2011

latch10

• Sooner Boomer
• May 14, 2011

latch7

• Sooner Boomer
• May 14, 2011

latch6 - a clear Christmas ornament half was used to make the optical window that covers the lens.

• Sooner Boomer
• May 14, 2011

latch5

• Sooner Boomer
• May 14, 2011

 

[neil_w]

You're wanting to do something like...

Cool, where are those pics from?

 

[Sooner Boomer]

Cool, where are those pics from?

From my gallery. Good luck finding it now that the new software is in place. I built that about 18 years ago, and have never flown it. I *think* I still have all of the pieces for the original nosecone. It's a tad bigger than your project.

See if this link works:
https://www.rocketryforum.com/media/albums/pave-latch-guided-missile.507/

 

[Sooner Boomer]

You might be able to do something similar to what I did by using the lens to a single board camera - closer to the scale you're working with. A google search shows some available, but it might be cheaper to just buy the whole camera and pull the lens off.

 

[modeltrains]

Would the end result be fully transparent, or would the flat coat make it a bit cloudy?

Can't say how much, depends on several things especially what kind of plastic and what kind of paint. What mainly I want to say is consider the effect of gloss and flat paint surfaces: gloss paint has what could be called a glass-like surface while flat paint has a surface that could compare to fine sandpaper, it is the irregularities which break up the smooth reflection. At the very least the after being flat-coated clear will appear fogged or frosted to some degree.
Also as mentioned is the thing about solvent and material compatibility, for instance, the old classic Testors glosscote and dullcote are lacquers and either one would craze clear styrene.

 

[neil_w]

From my gallery. Good luck finding it now that the new software is in place. I built that about 18 years ago, and have never flown it. I *think* I still have all of the pieces for the original nosecone. It's a tad bigger than your project.

See if this link works:
https://www.rocketryforum.com/media/albums/pave-latch-guided-missile.507/

Hey, nifty work there. Mine is smaller, also have a related but different approach to the nose (work in progress, to be documented soon).