Surf Bort Repair Thread

getting the glossy finish is all about proper sanding and polishing. Wet sand with extra fine paper, finish with polishing compound.

 

Word! I don't care how much wet sanding you do with 600, 1000, 1500 grit paper....5 minutes with some polishing compound will make it SHINE.

 

A few explanations....

You should always stick strictly to the 2:1 ratio for all 2:1 epoxy mixes. Mitch is right... that blurb is referring to poly resin only, and yes... it's a "hot" coat because of the additional catalyst that makes the resin kick hotter and faster. But... because epoxies are non-catalytic reactions, this rule does not apply. That's why they call the two parts, "resin" and "hardener," not "resin" and "catalyst."

As for getting poly resin to shine... hotcoats made from laminating resin with surfacing agent do not get very shiny. What gives poly resin it's brilliant shine is another additive... which I believe is cobalt... along with surfacing agent. In other words... it's gloss resin formulation, rather than laminating resin or hotcoat ("sanding") resin. If you want hotcoat/sanding resin, just add some surfacing agent to lam resin, and mix it hot with little more catalyst.

Epoxies cure through a cross linking process between two co-reactants, rather than a catalytic reaction where the catalyst only speeds up the reaction. All polyester resins would harden by themselves, if given enough time. But epoxies are different... think of it this way... one molecule of hardener has to "hold hands" with two molecules of resin, one on either end. If you have too much of either resin or hardener, somebody's not holding hands, so the chain polymer isn't thoroughly interconnected, and won't ever be as strong as if it were. That's why proportions are critical in getting max strength out of epoxies.

Epoxies will only become shiny with very, very labor intensive polishing. That's just one of the physical properties of epoxy compared to polyester resins.

 

^^^

 

If the resin set up fingernail tap hard, then you have no problem. Sand and polish as is. If the epoxy has set up for a day or so and is still too rubbery or gummy to sand easily, then i would try to grind as much of it off as possible down to (but not into) the cloth repair and re-hotcoat.

Here is my couple of tips for hotcoating with epoxy:

Do it in a HOT environment. I heat my shed to 85+ when working with epoxy. even hotter is fine.

Make sure the underlying repair is completely free of any oil, grime, wax, tape residue. these can cause fish eyes in the hotcoat. Any part of the repair or nearby board that is to be covered by that hotcoat has been scuffed with maybe 60 grit cloth to ensure bond. James Bond.

Mix the resin/hardener precisely 2:1 and stir stir stir. stir some more. maybe wait 5 minutes and then stir some more. Then hotcoat. the idea is to finish brushing on and brushing out the hotcoat just as the epoxy resin is nice and warm and runny and only minutes from gelling.

 

I'm about to begin my journey on several board repairs. Need thoughts from the guys who know best.

This board I picked up last night is relatively clean, however, there are several areas where the glass has been slightly nicked or cracked. Some areas show the fiberglass cloth. I will probably be conservative and lay down 4oz cloth, then hot coat. Does this sound about right or could I get away with just laying down a hot coat and sanding? I just don't know if I should avoid the hassle of putting glass on or not.

I'm not used to doing repairs on colored boards. Will the fiberglass cloth show up clear on the repair or will it give a white look?

Any advice is appreciated. Pics below.

 

Nicks and scratches don't really need cloth unless the glass is "shattered." Usually a good sanding and hotcoat/gloss coat and polish will make them disappear as long as the glass isn't white... which means it's shattered and will likely take on water.

Whenever the glass is compromised, cloth is needed. You can seal it up with just resin, but it will remain weak and will eventually crack and start leaking. Sand off all gloss and hotcoat, right down to the weave of the glass. Remove any frayed, broken or loose material, and do layers of cloth. Single layers where the cloth is still in tact, multiple layers where it's not. The cloth, if well saturated and laminated tight and flat, will be clear, so any discoloration underneath will show. Whitish areas will disappear if fully saturated with resin.

 

^^^ advice is on point. Thank you sir. I'm trying to tread lightly and not make too much of a mess on this board because it's too pretty to destroy. I'm gonna glass the white areas and just hot coat the nicks. As far as getting that epoxy shine, what grit sandpaper should I be working with? The board is originally poly and I'm using epoxy for my repairs.

 

If cosmetics is important, I'd encourage you not to do that. Epoxy repairs will work, but you have to prep very carefully. There's no chemical bond between poly and epoxy... only mechanical. And you'll never get the perfect match you're looking for. Epoxy just doesn't cure as clear as poly... they call it "water white," compared to crystal clear. Better to just go get a little jug of ding all ultra clear poly.

But to answer your question, to polish epoxy you have to start with around 320 or 400 to get the surface zits and wax off, then go up from there... all the way to 1500 grit. Then you have to go to a polishing compounds, usually two different grits, and you get the best results with a wheel and bonnet, although it can be done by hand.

 

Thanks LB. I jumped the gun and used my epoxy. I care, but not that much to get a poly kit. I have several jugs of epoxy on hand so that's what I'm using. I'm gonna try my best to use the high grits and get some kind of shine. It's gonna get waxed and rode hard anyways.

I appreciate your input. Will post some updates soon.

 

Thanks DP. Was that a package deal? I was in there yesterday, but only got 220 and 400.

 

Always a good treade when LBC starts dropping knowledge on board construction. I have learned a lot from you man.

What specific polishing compounds do you use if you don't mind me asking? I have been using Meguiar's #7 after wet sanding to 800 and had great results on poly. Have not tried it on epoxy yet...

 

I've use Meg's #7 forever, and with good results. Regular surfboard polish works well on poly, but not that great on epoxy as a finishing polish. You need to go to the next level and use an even finer product. I use a product that comes in a stick, but I forget the brand.

But even if you get the epoxy surface to shine, your only shining up a translucent coating, rather than a transparent coating.

 

Thanks for the info. This totally makes sense. I can never get my resin tints to POP with epoxy like I can with poly.