: Question Can I spray varnish over the sanded Carbon Fiber, Im thinking of
: sanding down the mirrors and removing all the surface epoxy resin and then
: spray varnishing them?

No.

You need the thickness of the resin, or somewhere around 50 coats of varnish to come anywhere near covering the carbon fiber with a thick enough layer of material to give you a smooth surface. The resin and carbon fibers add some strength. A mix of carbon fiber and varnish would be much weaker, and could be easily damaged by a few hard knocks or bumps.

By the way, you are not "drying" an epoxy finish. And thin coats do not "dry" faster than thick ones. Quite the opposite is true. A thicker layer of epoxy will hold and concentrate the heat of the chemical reaction, and it will gel and harden faster. When covering a large area, like a kayak or canoe, this is why we try to get the material out of the mixing pot and onto the surface as quickly as possible. Concentrated in the mixing pot the stuff will build up heat (hot enough that you can't hold on to it) and start to thicken. when the material is poured into a tray and applied with a paint roller it dissipates more of that heat and stays useful longer.

Putting the parts by the lamp is to gently bake them. They LIKE to cure at temperatures above room temperature -- and the 180 degree temperature I suggested is quite a bit hotter than any room I'd want to stay in.

Polyester resin is thicker, does not flow as much as epoxy, and can be mixed with varying amounts of catalyst so that it sets up sooner. So, you can put on a thicker layer without as many problems with runs and drips.

Because the carbon fabric has the texture of the woven strands, it would be impossible to sand down to it and remove all the resin without also sanding away a good amount of the fabric, and thus destroy the look of it.

If you have put two or three layers of resin over the fabric you should be able to lightly sand out the fisheyes and other glitches and then cover with a polyurethane. You don't need to spray this on, nor do you need a brush. Buy a 1/2 pint can (about $4 to $7) and just wipe it on with a paper towel or clean rag. This will give you a thin layer, and you can build up two to ten layers before polishing if you wish. Or, be practical and just stop at three coats. You can use a waterborne or an oil base polyurethane.

Hope this helps

PGJ