SO i did a very thin squeegee coat of Poly lam resin over the cured lamination just to fill the weave a bit and to fill any pin holes that might have been present. I must have not added enough catalyst to the resin because it was taking forever to go off. 30 minutes later I was wondering if it was ever going to kick. I decided that if I applied a hot coat over the ungelled squeeggee coat that it that it would probably get the squeegee coat to go off as well. Was this flawed thinking? Was that a big mistake? The hot coat went off pretty hot. It started to gel in under 10 minutes. I used UV resin for the hotcoat but also added 2% catalyst. I stuck it in the sun once the resin went off with the catalyst to give it a good cook. Is it possible that I now have an uncured squeegee coat underneath my cured hotcaot or do you think all is well.
the difference is that polyester cures by catalyst while epoxy is a polyaddition reaction.
Polyester will always cure eventually, the catalyst just speeds it up. A catalyst will also always leave the reaction when done meaning that it will influence the layer below.
Epoxy needs to be mixed very well and accurately in order to fully cure and both components are used to form the cured result. A new layer will have very little influence on the layer below. Applying a new layer with a surplus of one of the components will result in two badly cured layers.
Contrary to the opinion of one naysayer; Absolutely it will kick. Have done it many times and so have others. Sands too. Why is it doable? Don’t know. My thinking is that the bottom coat and topcoat blend just enough to kick top and bottom at the same time.
Background: Methyl ethyl ketone peroxide (MEKP) initiators are used to initiate the cross linking cure reaction in unsaturated polyesters. Since the MEKP solutions are consumed during the cross linking reaction the term “catalyst” is not strictly accurate but is commonly used in the FRP industry to designate MEKP initiators.
When a gel coat cures, the peroxide initiators react with the metal salts in the gel coat to generate free radicals. These free radicals allow the crosslinking monomers such as styrene or MMA to react with the resin polymer to form a thermoset plastic…
Doesn’t need to work with epoxy because of surfobard epoxy mixing of a 2:1 ratio (unlike PE resin). Small batches, say 6cc resin and 3cc fast hardener. properly measured and mixed just won’t happen. If you can’t properly measure and mix epoxy at a 2:1 ratio the chances of getting it right with PE and catalyst(non UV) would be difficult. If I was wobbly with my math and measuring tools, why wouldn’t you have a pint of UV PE lam resin and pour out a small amount, Put under UV light and start filling small holes and weave or just put on board where needed and then UV activate???
I’m thinking a whole new discusion category called “PE resin/catalyst help” to make it easier for PE users to find answers to question like these, and many others to include: what respirator will keep you safe, how to lawyer up when the neighbors call the feds because they think you are manufacturing crack cocaine in your house cuz of the very, very starange smell. Or explaining to little Johnny to stay away from the acetone and alcohol 5 gallon buckets with that lit cigarette in his mouth. My favorite of course… “how many weeks of post cure” of my freshly glassed PE board is necessary before I ride it because surf is cranking and I am going out no matter what you say. Thankfully the seasoned users of PE are here to assist, so this whole new discussion category of PE Resin would also be of help for them to check out and get some expert advice to the less experienced.
All this above concerns with PE resin is eliminated with a quality surfboard epoxy resin. One resin for every step of build. Two to one mixing ratio. Except for the neighbors thinking you are baking cinnamon buns when you crack the epoxy resin out, you should be problem free for decades to come with the build and durability of your pride and joy board.
NO! Why would I be talking about Epoxy? You stated you were using Poly. Going by your references to 2% catalyst and UV. Assuming based on that you are working with Poly. My comments are in context to your post.
Kick, set, harden etc are all references to the work in progress. Cure is post process. The time you let a surfboard sit around before you take it out and put heel dents in it. Same could be said for a cabinet door you just painted with semigloss paint. It has to set before you can sand or apply the next coat. But it has to cure before you can put the hinges on it, handle it and install on the cabinet. Smear hand prints, peanut butter on it etc. Know and define your terminology hermano.
Charlie is right, but I’m just not ready to give up that nasty Poly yet. The only problem I EVER had with Epoxy was when I found out what the term Exotherm meant a few years back when installing some handles in a few new SUPs. Friggin’ meltdown nightmare turn major ding repair. Friggin’ never happened again, that’s for sure.
You’ll be OK. If you are worried, let it cure longer than normal before sanding.
I laminated a board with epoxy and forgot to put hardener in the resin, as soon as I realized I forgot the hardener, I mixed up a second batch of resin and worked it into the lam. I let if sit for a week before messing with it and hardened up. It did mess up the coloring. Deck side is the messed up side. Actually ended up looking rather interesting.
Got to visit Oregon in August for 10 days. Surfed north of manzinita(sp) at a statepark we hiked into. Havenot worn a wet suit since imperial beach with a TJ sewage warming sign in 1999. Liked the vibe and portland , where i was staying with my army buddy, seemed more friendly than hawaii in my opinion. Came back ready to step up the aloha in my neighborhood.
Dropped off two surfboards on my trip. $50 to ship boards on alaskan airlines.
I would never argue that POLYESTER glossed and polished by a pro surfboard would ever take second place at a final surfboard finish show against full epoxy boards. The best fiinished board I have ever seen was done at an automotive shop with two part gloss urethane, polish and professional pin stripping by a lengend of the art. I imagine there is an automotive paint shop or two in every city world wide. Pricing out the effort and result, I am suprised more would not go this route than doing it themselves.
My first exotherm experience was with first generation proboxes where the side gap was a bit too wide allowing too much resin to get in cutout. Until later gen jigs came out I used to coat with 2 part epoxy paste and finger in a top coating on the cut out exposed foam.
Now of course, the use of milled fiberglass has solved the problem and using a longer pot life/slower curing hardener works everytime it is tried.
Attached photo of 1lb foam foil board double 11’ box placement. Milled fibers/slow hardener green room product… place, weight down and walk away with gaurenteed results as advertised.
First pic of high density corecell/Wood/core cork/wood/corecell sandwhich cut for double boxes
second picboxes placed, then peel ply. wood, weights to keep in place
Board will be a CF vac bagged bottom with CF/wood top.
