I have some decorative parts, I rather not sand them and clear coat. The finish is flat and no pinholes. However,there seems to be random issues, such as release swirls and other blemishes.
What do you guys use to polish epoxy surfaces? If I sand the part, it will just eat into the fibers, or if I sandblast, it might not leave a perfect clear finish after I clearcoat it.
I rather just buff to a shine, but have no idea what to use. Metal polish?
Thanks!
I just use the same stuff that I use for polishing molds and plugs. But I use the finest stuff (ie not course compound).
It all depends on how these parts were made. There is a chance while buffing the epoxy surface to shrink and get fiber texture due to increase of temperature. I would light sand, clear coat and then buff.
Have you used a gel coat or in mould coat? If not there may be fibers direct at the surface what may cause problems if you polish them!
If you made your part with an extra amount of resin it will work.
For small parts you can use a buffing wheel using white rouge similar to a jewlery polishing method.
For large parts you can use a car buffer with automotive liquid compounds like Meguiar’s machine glaze or 3M polishing compounds.
For a uniform satin finish, try sanding with white or grey scotchbrite.
The part is infused on the tool surface. no clear coat at all, so there will be some fibers on the surface, but I figure if I can buff out the blemishes, at least it will be an even finish.
Shoe, I don’t polish molds since I don’t have any. Just tons of flat metal plates. Which I don’t polish, but that would be easy since it’s metal.
GC, are these compounds normally for metals, or paints/gelcoats? Where are they found? (Home Depot, car parts, etc?)
The compounds are normally used for metals and paints, but will work for composites/plastics. Auto paint or part stores will probably have some. If not, online always works.
You might want to give 3M a call to narrow down what product would work best. They have a lot of different options available.
3M perfect-it or some glaze from Meguiar will do the job, just as any other ultra-fine compound from any other detailer.
Farecla g3, g6, g10 in that order
I believe Farecla is not available in the USA, but I could be wrong. Good stuff, by the way.
For polyester, I like the Farecla Profile 200, 400, 600 series.
Yes the profile series is good i like that too
ditto. Just go to an automotive paint supply and tell them that you need a fine polishing foam pad and buffing compound for dark surfaces. Start with med pressure at 1200-1400 rpm them light pressure (just the weight of the buffer) at 1800-2000 rpm for a glossy finish.
thanks for all the info. I actually grabbed some 5um aluminum oxide polishing powder, and made a slurry and used a papertowel 
it actually worked well for the weird blemishes enough to continue my work. Need to make sure my mold surface is perfect next time :-/ Wonder if postcure would fix it.
Post cure should not affect the finish of a demolded part. Surface finish of your part should only be affected by the mold’s surface finish or the release agent you’re using. Poly Vinyl Alcohol can leave an uneven finish or wax left on the mold may transfer to the part or imprint to the resin, causing the swirling you described.