FINAL SEALING COAT

It depends on what your final seal coat is,  Two that I know are safe are Future (insert current name now) and Alclad II Aqua Gloss.  Some other Gloss finishes may be OK such as Tamiya's Gloss coat.  Certainly never do it with anything that is not a high gloss finish.

The general and best practice is leave the masks on until all painting and weathering is done.

Hi Shipwreck!

 Oh, Good gosh no! Mask that Canopy. I sprayed some plane a while back, It was a Mosquito-Ya know the old REVell 1/32 kit. I didn't mask. My Bad!

 Although the product said,  Right on the can, "Will not craze known plastics, clear or otherwise! It didn't craze the major parts, but did a job on that beautiful Canopy and Nose.I don't remember the product, since it was a while ago and I used it up on car projects.

 it was so bad I had to take them off. Fill the craze with Glazing Putty, sand -"wet"- till they were glass smooth again. Then put new scratch built frames on them. Then, Vac-u-Form them. Mask those Babies or Baby off! Please?      T.B.

Mask the canopies.  Your sealer will likely fog the plastic, that is, etch it finely, and make it opaque.

Here is a post in a thread over at the Scale Model Addict forum to illustrate what can happen.  This is a '57 Chevy, nice build, till the modeler sprayed a sealer coat and didn't mask the clear styrene windows:

https://www.scalemodeladdict.com/threads/burnout.15608/

My . Mask it! Positively!

Stay safe.

Jim 

Definitely safer to mask them

Definitely mask your canopies.  Even if the clearcoat itself is safe for polycarbonate and won't craze it, it's still going to be nearly impossible to lay down that clearcoat smoothly enough to not compromise the transparency of the canopy.

missileman2000

I would mask it... 

I can't say that I know anything about the real canopies on real Starfighters, but I know that clear coats, especially flat coats, can craze or fog clear parts. Just to be safe, I'd mask, too.

-O

I would mask it.  During the time of service of the 104, canopies were not very UV resistent.  Under sunlight, the closs wore out quickly.  Later in the century, canopies were made with good uv protection, and the canopies kept their gloss for a long time.