eps sealing and venting question

Aloha, I am shaping my first eps marko blank and have read some conflicting threads about sealing with epoxy before lam and a vent plug. The eps is marko 1.9# small cell no need to spakle but do I need to seal before lam? And whats with the vent plug I thought this was only for hollow boards? I just want to shape it and glass it like normal??? Mahalo’s for help.

Hi Chris - One of the main points of “sealing” with either spackle (Cheap and easy) or epoxy, is to save you epoxy on the lam - so it doesn’t soak through the glass and into the spaces. I’ve never heard of a vent w/2#. I use 2#, spackle, no vent… haven’t had any problems.


you may want to drill small holes in the fin areas after you glass the bottom

so when you glass the deck you wont get air pin holes in the lam

they gass , period

vent plugs are a good safety precaution

a little heat and they pop


use a vent and save your board


i second that: use a vent when you have s…

you can make your own, there is a bert burger thread in here somewhere explaining.

it is reaaal simple.

or buy them peteC

i bought some.


Mahalo’s - Can I use Dap regular drywall spackle? And can you tell me were to buy some vents? Gets pretty hot on the island in summer. I’ll check the threads and see if I can make some too.

Liteweight spackle

Make a vent

drill 3/8 hole

fill in redrill and thread 10-32

make sure you drill on

both sides of the stringer

You can buy vents here


scroll down to “Sailboard Vents”, you want the 5/8" Vent, retrofit, with slot screw or thumb screw (R62-5119 or 5120)

or here


Thanks Ken I will try. And thanks Jonah I will order some for future use. Vent seems like a damn good idea.

I just put the lam on the bottom of a bioblank fish with RR epoxy - very cool stuff. Thanks for all the help to all swaylock braddahs. Brian from greenlight if your out there - the bamboo was fun too and friggin bullet proof. I don’t think the board will ever ding.

I have glassed somewhere around 600 EPS/epoxy boards in the last 2-1/2 years here in Hawaii. About 35-40% of them are 1.7PCF. The rest are between 1.9 and 2.1. They are nearly all spackled and have a variety of glass schedules. Many of them have travelled on planes and all of mine have lived in my black car, sometimes for over a year. We have not had one single delamination due to air travel or heat issues. I postcure them at 140F for a few hours. Glass the board correctly, no vent plug needed. It’s masturbatory.

Did you buy one of 'em fancy city folk type ovens? Or are you a fan heater and a box type of person? Personally, I was thinking of using the glass house. Just need to keep the humidity down.

Hey chrisupp

Glad you like the bamboo. Maybe you can post a pic of the board for all to see.

If you vent the board, remember to open it after your sessions or it’s useless.

Regarding screw-type vents (part time venting) vs. Gortex-type vents (full time venting) - is either type more preferrable? I’ve read it’s a good idea to rinse a Gortex plug with fresh water to remove salt residue, which chould be considered a drawback…but so is having to remember to open and close the screw-type vent.

Knowing me, with a screw-type vent I’d likely forget to close the vent cause I get too excited when I roll up to the beach and want to get in the water ASAP! If I ever got water in my board from neglecting to close it, I’d have a hard time forgiving myself…

That being the case, Gortex-type vents get my vote. Anyone have a good or bad experience with Gortex?



Mahalo’s Bammbamm,

How are you post curing them? Any suggestions for low budget style cure box? And do you cure them after there done or before the gloss coat? PIctures coming soon if I can ever figure out how to paste them in instead of stupid attachment.

I’ve laminated Marko with no seal and it was no problem. I think generally this is the case. If it does drain a little, come back with a 3 oz. batch cheater when the lam is still rubbery.

As for vents, no need with Marko … at all. In fact only 1# foam should be considered for vents. All the stuff heavier than that doesn’t need it.

Thanks Greg - I laminated today using your epoxy with bamboo fabric and a bio blank. It was a miracle. I had all day to get it just right it seemed maybe 20-30 min easy were as with poly I was getting hung up with lumps and thick spots cause I’m so slow and it would kick before I was happy. I will only use poly if someone asks - only RR from now on. Mahalo’s for helping!

so you say #2 eps doesn’t a vent… that’s cool.

but what about a 12’ x 32" x 5.5" SUP ?

I told the guy I made the sup for not to leave it in direct sun and really take care of it untill I’ll get

one of those vents and install him one. do you think it’s mandatory to put one in such a board?



Here’s a related question:

I haven’t had issues with the glassing and no issues of the boards delaming (all are 2# block foam, hotwired, some stringers some not, sealed, RR epoxy), BUT… I have had some big issues with ding repair on a few!!

If I have a full breach in the glass, clean and prep and then fill with resin + cut glass or filler; the board offgasses sending a steady flow of air bubles through my fill not allowing a proper seal : ( (this happens more when it’s hot)

The only way I’ve found to avoid this in the summer is to prep the board and fill the ding with resin/filler in the hot garage and then bring the board inside and let it cure in the AC. May be my cheap foam? Any tips? Anyone?

I really miss Solarez!!

I would buy a plug just becuase ding repair if you take on water will be much easier… and so far ive been unfortunete enough to have taken on water in almost all of my past eps boards for some reason or another.

Aloha Greg, Board went very well. I had one last question before I gloss. I’m using FCS plugs and am worrying about heat build up from the large pool it takes to do these. Do you have a way? Some threads in the archives suggest it will melt eps making it brown and your fin will pull out. Many Mahalo’s

GL doesn’t seem to be online and you’re probably itching to do your FCS install so

I’ll jump in here and try to help…

Take your time and do the install in two pours, letting the first one exotherm and cool

before you do the second. It’s the volume of curing epx (in a column inside a very effecient

insulator) that is your enemy. Cut down on that volume by not doing it all at once. Doesn’t

hurt to use the wet rag trick on the deckside as soon as the resin sets. Also do the install

when/where your ambient temps are lowest.

Next time use the FCS Fusion system, it’s specifically designed to eliminate these difficulties

and the preglass install with fiber ‘‘cap’’ tests out stronger. Or if you use the normal plugs, put

high density inserts in the shaped blank before glassing. Then you do the install with no H-pattern.

Another option is a low-exotherm epx formulated just for doing conventional installs, it’s made

by Greenroom.

Mahalo’s Mike,

I will try that tonight. Do half first - it will be about 70degrees maybe 68 at the lowest. Has anyone tried a frozen gel pack on the deck or is that too cold?

Can I ask also if the half pour method would be necessary on bio foam blanks as I use those also but haven’t put fins on that one either???