From what I’ve read on here it appears to be taboo using polyester resin on top of EPS/Epoxy. The reason I bring this topic up is in an attempt to significantly speed up the epoxy repair process. With hours of time required waiting for epoxy to become sandable, the jobs I take on from start to finish can take me days / weeks to complete depending on the workload, my schedule and availibility to dedicate more than an hour or 2 a night (I do this part time after my day job). The cons I’ve read are that poly doesnt stick to Epoxy and will chip off over time. Poly melting the EPS foam will not be a factor as the foam will be sealed by whichever filling agent is appropriate. I’m curious to the real-life application and life expectancy of patch work using polyester resin repairing EPS/Epoxy Stand Up Paddleboards.
My proposed method is to dremel out damaged area needing repair. Not shy when opening up these large SUP’s with holes and cracks to expose good foam and enlarge the hole to rid the board of “loose” glass. (Fiberglass that pushes down too easily near the intial problem area and doesnt appear to be adheared to the foam any longer.) I then taper the lip of good glass and fill the abscess… This is where things get a little unorthodox. Atleast IMO… To speed things up I’ve expirimented with all sorts of fillers. 8lb density polyurthane pour foam seems to work quite well. On intial contact the pour foam melts the EPS foam about an 1/16" but as the pour foam expands, the melting is neutralized and the expansion re-fills any gap that may of formed. The pour foam usually “muffin tops” up and out of the hole and is sandable in about 20 minutes. (sands very easily) Once the pour foam is sanded sub-flush to compensate for the 2 patches of 6oz e-glass (1 patch being cut to size of repair and the other patch oversized about half an inch on all sides to allow feathering while sanding before hotcoat). And the other key factor I would like considered is prepping the “original epoxy laminated glass” surrounding the repair by really scuffing it up with low grit paper (36 grit is what comes to mind). This in theory would compensate for “poly not sticking to epoxy”. I would wet out these 2 patches with UV Catalyst Poly and expose to sunlight to hardern. Should be sandable in just a few minutes after baking in the FL summer sun. I would use 80grit or so to feather out patch edges and re-rough up surrounding area. (might consider doing a final pass with 36grit again in a nice contained manner/ strictly the area I will be hotcoating… in theory compensating for any incompatibility between the two resins) I would then tape off the area to hotcoat and prep the Lam Poly Resin with Sand Aid and proceed just as any poly hotcoat job. Let kick, usually takes about 1 hour or less to become sandable. Taper the hotcoats lips with 220grit. Prep and paint to conceal repair.
We have a few “burner” boards around the shop (boards that cost more to repair than are worth and customers trade in towards new or just want to give away)… The plan is to test this method on some of these boards before doing this to any customers board. Just wanted to reach out on here and bounce the idea around.
…or any other high quality epoxy. My current favorite is Greenroom Old #7, sands nicely without additives or a post-cure.
Meaty, I am all for you repairing boards and saving time when possible, but I would use an epoxy resin and a lower density foam for the repair so as not to make a new break point, where the foam is harder and the cloth is not as strongly bonded as before.
Take a couple burners, cut of the noses, and make the same repairs with your material set and with epoxy resin and see what you like and what lasts better in the end.
You are exactly “right on point” in your method. I do not however believe 36 grit is necessary and creates work… Scratches that are sometimes hard to hide. Once EPS is filled with a filler or covered with 2 or 4 oz. cloth; and there is no pssibility of Poly Resin seeping into or onto the EPS foam you can absolutely us UV Poly to finish off the ding. Few know it but it is MEK Catalyzed Poly that creates the problem . Not UV Catalyzed Poly. I used you method for years on EPS ding repair on Sailboards while living on Maui.
Is there a certain brand of 5 minute epoxy that you’ve had good results with? The first thing that pulls up in my google search is the locktite brand and appears to be about $5 per single-use looking tube. Maybe 2-4oz.
It could be that I’m over thinking the problem. I’ll buy some R.R. Kwick Kick and test the cure times before I go crazy with the poly. What I’ve been using is 4:1 US Composite Epoxy. Even with a dash of the epoxy accelerator it can take more than 2 hours to reach a nice sand-able hardness… no chipping or weird gumming up.
I believe i remember the US Blanks in Melbourne mentioning that they carry green room epoxy. I’m based on the west coast of FL but make my way east quite regularly. Are there certain distributors you could recommend?
Maybe the 4 or 6 lb density pour foam would be more appropriate? Haven’t had really any negative feedback on the repairs re-cracking but most of the repairs aren’t made in critical areas of the board. For example… they come in cracked and damaged because the customer dropped their 12’ paddleboard trying to load it on the car rather than blowing a fin box out while surfing.
Ok great advice and excited to hear you’ve found success using a similar method! That’s very interesting about the UV catalyzed poly versus the MEKP catalyzed poly. If you could elaborate, that would be very helpful information. Maybe 36 grit was too extreme. 60-80 grit could do the same trick? In theory I was thinking I could really hide the super low grit prep work by the final hotcoat and then feathering down using 220 as the lowest grit. Any deep low-grit scar visible under the hotcoat is hidden under the final paint job. (Sometimes cheap rattle can, sometimes expensive auto paint out of the spray gun) depends on the customer and board.
Milled fiberglass fibers with as fast as possible cure epoxy. I use green room with west coast fast hardener. When you mix with milled fiberglass the exotherm foam melting no longer is an issue. Depending on the intended use, the thickness is adjusted by adding more milled fiber to the epoxy. So small volumes of resin can make lots of resin/fiber combo to easily control from running, able to place a release film or peel ply over and tape( like a rail repair) the goop making a close to perfect, minimal sand job readiy to glass repair. Sometimes I will put the fiberglass patch over the paste like resin/milled fiber combo and place some peel ply barrier and tape for a very quick repair. Maybe 2 hours total if west coast fast epoxy hardener is used.
Also being the self proclaimed forrest gump of milled fiberglass and green room epoxy resin , I submit to you my montage of uses to include:
Fake cocaine
Fin box placment
Leash plug placement
Vent placment
paddle repairs
nose/tail block adhesion
Major snapped board repairs
Don’t forget the peel ply or release fim material when weighting down or taping to make matching contours so a smooth finish allows for mimimal sanding and overall effort. Also the repair wll pull free from the tape or weight.
Poly finish over epoxy lam was the way to go some years ago. I know pro builder do it always. No real problems if epoxy is well cured and prep. Some époxy can inhibit poly hardening but not modern surfboards epoxy. Because époxy can elongate more, on impact poly can chip off while epoxy lam stay intact. Less with isophtalique poly. Some specific iso poly finish coat for boat can match very well epoxy lam. Some surf builder do first lam layer with époxy then last lam and finish with poly. Old coil for exemple.
Thanks bb30! The skul 100 is hilarious! Our shop only has an evil clown :( Might want to attach a shop vac system to help it mow through those milled fiber lines haha.
I’ll definitely be picking up some of that milled fibers 1#. Ive read about them before a bought “chopped fibers” thinking they were the same thing but from the pics I can tell they are completely different. The chopped fibers are like rigid 1/4” strands that haven’t really worked for me in the past. I put the container far back on the shelf and haven’t thought about it much.
And since you’re using the fiber as a filler I’m assuming there is no need for cabosil?
Lastly I really like the idea of putting cloth over the repair during the fill stage. I guess it eliminates a step if done correctly. All that’s left is sand-hotcoat-sand-paint. And from what I’m reading on here, it really wouldn’t be the end of the world to do the hotcoat with poly. Quick set up time and nice to sand
Thanks lemat! I hadn’t even thought about doing boards in different layers. First one being epoxy to seal the foam and then going to poly. Might save some $ on material cost as well as time.
So maybe if the repaired area were to be impacted greatly again, there might be a chance of the poly chipping off and having to redo the repair? But as long as there is no further damage to that specific area, the poly should not chip off strictly due to aging?
Part of the reason that it is not a problem is because the UV sets so fast that it doesn’t have time to drain or melt the foam. I have applied UV Poly directly to EPS on a few small repairs. The best known ding repair man on Maui used the same method, but tried to keep it a dark secret. Never tried to glass an EPS Blank with UV tho.
1/32 is the smallest I have been able to buy. I think that is the smallest. Most ding repair is done with Q-cell, but Cabosil is very handy to have around any shop… it works as a thicker and stays clear. Don’ t know if you have ever viewed Loehr’s film on Glassing with Epoxy, but he uses it for finboxes and butt cracks etc. for deep gashes I Sur-Form EPS Foam into a clean pail and stir it into watered down lite weight spackle. Makes a slurry that I fill the gash with. I did that recently to a damaged SUP Blank. I can’t even find the repair. Lowel
Yes, with most modern surfboards époxy resin, if well cured and well prep ( freshly Sand scuff with 80grit or lower) no poly chip off alone only if ding exactly like a poly gloss on poly lam.
