How to protect/seal frosted glass spray The frosted glass is specifically to diffuse an RGB LED lamp thing I made, so every scratch and other degradation on this thing so far is very prominent. There must be 8 coats of Rustoleum frosted glass spray on it. It's a very thick matte finish.

For all the frosted glass tutorials out there, like on wine glasses, you would think a few of them would post an update that everything came off or otherwise looks terrible after a week, and perhaps a few would have shown how to solve it.

My concern is that whatever enamel or acrylic spray I apply will either add a gloss, or reduce opacity by filling in the surface and eliminating any light refraction.

The only constraint is that I need to be able to buy it nearby at Walmart or Home Depot or something. I won't have time to order it online because it's a gift. Preferably a Rustoleum product because it's cheap. Would the American Accents Ultra Cover Matte Clear work?



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Given your time and store restraints, I would agree with your choice of a rattle-can/spray can of matte clear coat.  I don't know the brands well enough to recommend one over another.

There is the potential that the clear coat will reactivate the frosted coats, even if they are thoroughly dried and cured.  So apply very light coats from twice the recommended distance and allow each coat to dry before adding the next.  If the frosted coat does reactivate, it will mix with the clear coat and thus dilute or distort the frost.  The less of the clear coat you apply in each protective coat, the less chance of ruining your artwork.

It might be wise to frost up another piece of plastic and after it dries, test the clear coat on it before risking your art.

If you had more time, an art supply shop (or Hobby Lobby), and an airbrush, you would have more options.  Createx Airbrush paints has a product called Intercoat  which would be perfect for this situation.  It provides a non-reactivating layer to protect your existing artwork from the solvents in any paint or clear coat which you might apply over them.  Spraying a layer of Intercoat over your frost paint would lock it in place, allowing you to add a matte clear coat without any risk of reactivation.