Hi guys, first post here after browsing all the awsome threads for a LONG time. Anyway, I build the odd shortboard, but mainly build custom surf lifesaving boards here in OZ. My problem, and that of many other brands at various clubs, is the delamination of the topcoat from the lamination layers. Most guys that build these boards use the Kinetics epoxy (surfboard formula) and the label says "superior adhesion to polyester". In my experience this does not happen, all I and other board users get are huge chunks of top coat flaking off, artwork too, and a glazed oily-like lam texture underneath. Ive tried the scrubbing with water, sanding (too expensive on paper) but no use. My shortboards dent up a bit, but the top coats never bond. Does anyone else have issues with this product? or is this just the norm? Note, I laminate in the Kinetics Ultra white now, and I think its harder to get the Polyester (Silmar) to bond. And it takes forever to really harden. Any help is greatly welcomed. Thankyou
I’ve done 3 boards with Kinetix (actually, I’ve done 3 boards in total, so I’m no expert), but I’ve kept it simple by doing epoxy lam, hotcoat and gloss. Epoxy on epoxy bonds great, so no delam issues. On a 25C day, I find it has hardened enough in 24 hours to sand quite nicely. Give it a few days to a week and it’s rock hard. This is with the regular kinetix, not the ultra white, but the ultra white is meant to be a slightly faster cure.
Also, the oily lam sounds a lot like blush, which might explain why the poly is flaking off. I’ve not generally had blush issues with Kinetix, in fact it’s only blushed on me once and that was when I hotcoated on a very humid and hot morning. But I’m in Vicco, so humidity is rarely an issue here, except this summer! As a backyard hack, I can’t complain about Kinetix at all.
Cheers
Paul
dont use polyester to filler coat… use epoxy.
polyester will never stick 100% to epoxy!
Thanks Paul. Ive asked around the big brand board factories, some are switching to Resin Research epoxy for lamination & topcoat, but ive never used it. Does it have the same blush issues your talking about? I find the Kinetics horrible to sand, which is why most people use Polyester topcoats I assume? Just want to have my boards (espeacially nipper boards, little guys trash those things!) as durable as possible without the flaking delamination. And If I can save time and effort, and win lotto, that would also be handy! Thanks guys
i have used both kinetic and RR KK, i have chosen to keep using KK on slsc boards. i have never had blush issues, only issues with paint sticking. once we solved those by using the correct chemicals they were fine. how do you set your fin boxes in the eps boardpro?
So, this isn’t really a case of delamination, then? Delam is when the fiberglass gets separated from the foam.
You are apparently describing a situation where a top coat of poly is flaking off the previous coat of epoxy. While I have never done poly on epoxy, most everyone I know who’s tried says “don’t do it”. Others may have had better luck.
Thanks Dave. I might try the Resin Research on my sons board this week. Will let you know my results. Fin boxes? I set in a high density foam block 1/2 inch bigger than the box itself, then rout in the box as snug as can be (easier when you have jigs for each size box). I find my boards have alot less box problems when Im down at the carnivals watching the events, but if you hit the sand or another board hard enough all box will break, unfortunately! The SLSC industry is a big market, Im surprised more guys are not on swaylocks, or maybe they just read all the info like I do.
SmmyA - your right, its the topcoat coming off the epoxy lamination. The kinetics guys ive spoken with swear there is no issue with bonding, I guess they dont build anything themselves personally. Top coating in Kinetics leaves a gummy surface, and its a while before you can sand it. Being a small number builder, Id like to speed up my process, without reducing quality, and hopefully get rid of the flakinig issue. Thanks again
Even our RR formulations will have issues with hot coat delamination. We solved this another way a few years ago by introducing epoxies that have flip times nearly as fast as polyester (in fact faster on warm days) and also with the introduction of Additive F, the miracle sanding agent which makes epoxy sand just like polyester. This solves the peeling hot coat issue, the sanding and finishing issues and offers a stronger board with even better durability. Polyester hot coats are something we did 20+ years ago. It sorta works but not really. There are builders in CA right now who are still thinking this is something they can do. More and more their seeing that they’re getting significant return percentages and the longer they continue the bigger headache they’ll face. In the long run this has never worked and IMHO never will. Glosses … yea … they work ok, but not hot coats. When the savings in using a poly hot coat are a couple bucks and there’s no real production advantage, why would you go this way?
Why, because there are lots of dummies out there.
I disagree. The polyester sands horribly. The poxy sands great. No more gumming! Use my sanding papers longer too! I am sanding all the poly work with water and wet-sanding paper.
Epoxy on epoxy only.
Kinetics cures harder and sands easier with a post cure.
I had a little space heater in my glassing room and held the temp and about 40 degrees C for 8hrs.
Shorter times if you can safely keep the temp higher.
Or, leave it to cure up high in the garage for a week.
My opinion?
Use RR for all steps
Cheers
Back in the late 80’s I was working at a shop that was glassing Hi-Tech windsurfers for G&S. They where doing polyester hot coats on epoxy lay-ups (everybody was back then). The slalom boards they built had a hard edge all the way around the bottom, that was made in the hot coat by damming up the edge with tape. One day a slalom board’s bottoms edge hit a door jam when being moved into the sanding room and the hot coat popped off where it hit. By pulling on the spot the whole bottom hot coat peeled off perfectly. The thing came off so clean, that when I saw it, I asked if I could keep it and use it for a template. Another time the sander cleanly torqued off half of the bottom hot coat sheet when sanding it with the grinder.
I contacted the Resin Research guys on the Gold Coast, very helpful, picked up a kit of the new KK formula. Their own testing (they actually build boards, repair everything!, and surf.. wow.) and the feedback from RR users sounds pretty good. Ill be laminating a new nipper board today, they said I could easily topcoat it aswell all in the one day! No prepping/sanding between coats..... I'll follow their instructions and wait for the outcome. Thanks for the advice here guys... Ill be watching these boards keenly from now on.
So... I did my sons board today. Followed the steps, and I gotta say, that was the easiest lam/topcoat/sand Ive ever done. All in the KK formula. Ive put up a picture of the common damage on SLSC boards, the delamination of the poly on epoxy. I also did a test panel to see if the Resin Reserch epoxy would seperate and delaminate like the common boards do. To my excitement, not one bit of chipping or flaking! Of course it dented when I hit it hard enough with my rubber mallet. hope my boards turn out as good as my test panel. Thanks guys for your help, I hope my post here helps others in return!
