Epoxy gelcoat

Found only a couple of epoxy gelcoats that say UV resistance?...Novalis Topcoat C219 and Resoltech 7060

Guys know of any others and whats been your experience?

SP CR3400 suggest the use of a topcoat, not sure about the Sicomin 715, says "UV stable" on website but not in spec.pdf and "boat production" is not included in recommended usage... But both familiar names...

Also a polyester-epoxy option.

 

-any epoxy will yellow over time, so steer away from epoxy gelcoats if possible. However, parts with a shorter life span, or no importance on looks after 15 years, are being made in EP gelcoat if the need is there. (I am talking about canoes, canoe paddles, etc.)

Also parts which are to be painted use EP gelcoat sometimes. (some Mercedes truck parts are EP with EP gelcoat, spray painted after assembly). And many more.

Parts that are not likely to end up in UV (sun) can have EP gelcoat as well, I remind the patient tables for MRI scanners of both Siemens and Philips. The gelcoat is there for hygiene reasons.

-there is a market for UP (unsaturated polyester) gelcoat, which accepts EP as laminating resin, but not in boats. I saw the Scott Bader product in your list. MG Scheufler / Bakelite / Hexion / Momentive (can EP manufacturers please stop changing names??) makes a similar product, called T30 and T35. These are mainly targeted towards the production of small airplanes. Continuously being submerged will damage the gelcoat in no-time, just peeling off the epoxy laminate. In my osmosis tester (distilled water @ 60 degrees C) this stuff peels within a week or 2.

-this leaves you with 1 option: Normal UP gelcoat (for boats preferably ISO-NPG), with a UP or VE skincoat behind it. Use peelply if you can, but be careful with removing it, not to demould the skincoat. My simple tests showed that peelply was an absolute winner, over sanded, non-sanded, sprinkled with short fiber, and sprinkled with sand. I was able to peel all of them loose, after prying loose with a chisel, except the peelply one.

 

With what (skin)resin did you test Herman? I have build a few boats with skincoats, VE resin, unwaxed. Haven't had problems with delamination

 

I tested unwaxed VE resin, hand version. (Polynt Distitron VE100S1T)

During normal use I do not expect delamination, but I was prying the skincoat loose with a chisel and hammer (nothing scientific)

 

nothing scientific, but you've got resutls that show. (normal method at the places I worked, haha.)

 

Wouldn't an epoxy gelcoat really be just an epoxy paint and if you had to redo it every 10 years what is wrong with that.