Hello; few weeks ago I laminated something with a non surfboard resin then applied a filler coat (epoxy too) and let it dry for couple of weeks however when I started to sand it down I noticed that all the filler wanted to peel off and in fact did it.
Epoxy resin is only a great glue and a crap for most anything if you do not have the right conditions of weather and possibly that could be the culprit? You know, cold plus humidity.
I warmed the resin and the proportions (5:3) were right.
I am not talking about a finish coat where you can sand the previous coat to 80 to have anchorage but you do not sand a stratificated surface to apply a filler coat…
Hello JRandy; I do not know but I did not perceived anything different. The stratificated part finished pretty good and previously only sanded the surface (epoxy) with about 80 grit and not so much.
I though that some one here could had this problem.
I’ve heard little good about some of them employed outside that application, but for their initial price.
I think they enploy a surfacing / self levelling agent, and secondary bonding is of no concern whatsoever to their formulation. I think they are more tolerant of heat than surfboard epoxies and are a bit harder too to resist denting from bottoms of slammed beer bottles.
The old classic blush epoxy problem. Free amine hardener reaction with air humidity. That was each batch on old days before no blush epoxy (or addF for RR). + Epoxy cured glossy so bad mechanical adhésion any way. All surface let cured past tacky stage must be prep before cover: water wash to remove blush, Key sand to remove gloss. Or use a Peel ply.
No voc blush free epoxy is a big improvement if used in good weather just light sand key is needed.
More often a light blush is not visible and spread around surface by sanding process. Better prep is to scuff with coarse scuffing pad and water, remove blush and gloss. A light filler coat on green, tacky, lam give something to sand before recoat.
Your story remind me my started with epoxy in 1989. Blush each batch, cover with plastic release film to avoid when possible. At that time everyone around me finished epoxy parts with polyester top coat. Epoxy was stiffer so less cracking compatibility with poly finish.
Hi Lemat as mentioned, was not a finish coat The problem was with a filler coat so I do not perceived any thing different with the stratification. You do not sand the stratification…
I fill lam when green with a squegged cheater coat. Window is when resin start to make strings attached to glove when you touch it up to still taky. For 4oz glass I use around 100gr (3oz?) of resin by square meter i spread with a soft squegge and finger on rails.
I sand prep this layer, 80 grit to flatten it up to touch fiber here and there and scuffer pad to remine shiny resin left, then i brush finish coat.
3:5 is a weird ratio, I imagine it would be easy to screw up, especially if mixed by volume in mixing cups that say its graduations are generally accurate.
Looks like an Epoxy to avoid though, whatever it is and another ‘+1’ for not using non surfboard specific epoxies on surfboard laminations, whenever possible.
I’m using a more budget friendly surfboard epoxy easily acquired locally, that is not without its issues in regards to fisheyes and formation of blush, and is likely also bad in the yellowing department, if I ever glassed anything white. It will be my last batch of this brand, and I am inventing uses for it where its poor qualities will not be an issue to use it up faster to get something better the next go around.
Yes, i bet that’s your problem, resin blush in cold and humidity. Go with filler on tacky lam to avoid it. Water wash and sand all shiny when you have to cover Harden resin. A hot box would be a must too. And if you can use addF from resin research, it’s firstly make to avoid blush and work very well.
Hi Lemat; may be is the different languages but I mentioned 2 times that the problem was with the filler coat. I applied the filler coat onto an stratification that filler coat peelled off. You laminate a surface (resin + fibers) and there is no way to see that blush…
—Yes; 5:3 is strange. You know; 10 parts an 6 parts. Possibly a generic pourpose resin. Made in Korea. No R R or similar here. Last time I worked with epoxy was in the late 80s. I do not see any improvement if you do not use wood, PS etc. Also you need to have the right room and conditions.
Sometimes you cannot have the controlled room due to you are working on stuff that are outside or in a big building etc.
Yes i understand fill coat Peel off lam. It’s because resin of lam blush so no new coat over can glue. Blush appear while resin became hard when it became no more tacky. It’s sometimes difficult to see it specially on lam because of fiber texture. That’s heppened every batch of resin, no more with modern blush free epoxy. Fill coat on tacky lam before lam resin blush is one way to avoid filler peel off. Other way is to use a Peel ply as last layer of lam process so when you peel off blush with ply. Or you can water scuff Harden lam to remove blush. Last trick is to use addF.
I don’t understand well, my english is realy basic…
Blush is a contamination of surface, works like when you put wax in mold to make parts.
One day i saw big adhesion problems when sytem that take off oil of air compressor fail. They use it to clean surface before lam, catastrophic…
Blush was a realy often problem when no blush resin was use. Epoxy board builder i know Always use the Gougeon’s (west système) protocole : clean lam with water and scuffer, dry, sand then you can cover with resin.
When i start work with epoxy in 1989 i learn blush hard way, then i do this protocle each time. With blush free resin i stop it except if i have a doubt even if i work in regulate temp and humidity space.