Recently i bought -and was a pain in the ass in terms of price- some quantity of clear epoxy gelcoat. The brand was R&G.
I used it -by brushing- in one of my moulds and the result was a disaster. The gelcoat is not that clear at all, and it tends to give a white cloud in places where the gelcoat is somewhat thick and dull where it is thinner.
So, i have two options now. Either not to use any gelcoat at all and learn to live with potholes on final part’s surface or use the PE clear gelcoat i already have.
The question is, what is the best method of applying PE clear gelcoat. Brushing or spraying? The latter is the most obvious answer but i think that i will get bubbles inside the gelcoat due to air pressure. What do you think?
Do you think i will get best results from “Duratec Hi-Gloss Crystal Clear” pruduct?
i remember reading that with clear polyesther gel coat you should only spray it to avoid the milkyness
Spraying is always the best way to apply gelcoat. But brushing can provide acceptable results on small parts. Often times, thickness over 30 mils will cause cloudy patches.
BTW, where in Spokane are you at? I was there this past week working with Triumph Composites to solve some of their problems.
The duratec works good but you have to spray it
Spray PER (Polyester resin) gel coats
NEVER spray Epoxy face or gel type coats as the fumes are deadly!
that gelcoat you bought is for use with colouring paste, thats why it’s milky, not transparent.
to spray neotex’s transparent polyester gel, you have to use 3-4mm injector size, thin it out with about 2-5% styrene (buy that from neotex too) and air pressure around 3-4 bar. from that you get a nice surface, which makes vacuum bagged carbon look flat, while if you brush it, the vacuum will make every stroke apparent on the weave.
oh and in this greek summer, only 0.5% catalyst, and WORK FAST! you will barely have 5-10 minutes before it gels.
** another cause for porosity, gel or no gel, is the damn fabric. don’t buy the 200grm twill they have at neotex, buy the 245! its much more tightly woven and leaves no space between the weave.
I can see your problem… brushing epoxy resin to get even color across the mold. Try using a roller instead of a brush. Brush on one light coat. Once that sets to tacky but able to touch it without it coming off on your finger… roll on another thin coat.
If you get small air bubbles use a small butane torch about 8" away from it to remove the bubbles. Use the torch right after you apply each coat of epoxy.
It should look good… remember YouTube “Carbon Fiber Cello”? they used epoxy surface coat and made a beautiful cello.
Wait, they used an epoxy surface coat on the “carbon fiber cello”? I thought they just straight vac-bagged it with no surface coat. I know they brushed epoxy onto their mold first but I though it was immediately followed by a layer of carbon.
fastrr i know the epoxy gel he’s talking about, its not nearly transparent, its milky white. it just can’t be used for this purpose.
Ohh that sucks. It would be good for painted parts though.
I’m hoping this HTR212-386 is clear … if not ResinServices has a clear hardener for the HTR212 that makes that resin a good clear epoxy surface coat. In the next month or so i am going to make a few molds and try it out.
im out in the valley. My roommates dad works out at triumph. Ive been looking at a job out there for a long time now.
fastrr-- it’s clear. clear as straight bis-f. appears unfilled.