Cut lap noob

This is my first post on this site but I’ve read a lot on here and have gotten a lot of help by doing so. Thanks for all the help and for being so cool. I’m new to shaping and glassing, I’m currently on my fourth board. I’m pretty happy with the results so far, but it’s something I wanted to be really good at since I was about 10. Anyway, this time around I want to try cut laps.  I have a good enough idea how to tape and mask for this, my question is when do I cut? While resin is still wet, or when it’s fully cured? I’m using EPS/epoxy if that makes any difference. Thanks



Hello Guy Paul,

For me it works best to cut when the epoxy has set enough not to be sticky or prone to delam, but soft enough that the cloth and resin can be bent and cut with little effort.  Some call this a ‘b-stage’ condition.

I’d make a practice piece with your cloth and resin, get it taped, lammed, and cured to b-stage (your time to b-stage will depend on temps and resin, etc.), and then take a test cut. If the cloth still wants to delam, wait another 10-15 minutes and try again. Once the sweet spot is found it is a beautiful thing. The cutting tool should be sharp and watch out for the fingers.

Here’s a video from Fiberglass Hawaii, there are also good threads with pics here on Sway’s to be found by using the search bar. -J




Rad! Thanks a lot I really appreciate it

Just past the stage where it makes “strings”.

If you touch a drop of resin with a toothpick then pull it away and a “string” of resin follows the toothpick, it’s too soon… Just after that and it’s perfect. Too long and it’s a huge hassle.

When it isn’t sticky anymore, but still rubbery. After razor cut, clean up the cut with a small block plane

I grind the laps of when there fully cured with a die grinder. Sets up for a really flat lap so you dont get build up from your deck lam. 

I have no board making knowledge but I know a killer thread title when I read one.

Hell yeah guys thank you all very much. Another question if you don’t mind? I’m going to do 6oz on the bottom and 4x6 on the deck. I’ve comfortably glassed a 4x6 at the same time with free laps, but should I do one at a time with cut laps? Also, when doing this, should I glass the bottom or the deck first? Thanks again 

I’m not sure it makes any real difference, but I always glass bottom first.  

As for the other question, the video posted shows how to do two layers of glass at the same time (one layer gets cut at the rails, while the top layer wraps around), but I like to do mine separate.

   Point in fact, it does make a difference.

I heard at one time the glassing sequence had something to do with preserving rocker, but thought that was due to the foam and resins of the time, i,e, shrinkage during resin curing, just wasn’t sure the same issues existed with EPS / epoxy as the original poster is using, or with poly / epoxy, as I favor.  What is the current understanding on this?

That is correct.     Light weight foam, stringerless, and with stringers less than 1/4th inch, would lose rocker if the deck were glassed first.   

OK, got it, thanks Bill!

What is the difference? It seems in my opinion if one did both deck layers first, then did the bottom layer, it would make for cleaner more sealed lap lines. But again I’m the noob, and a sponge. Can’t get enough input. Much appreciation. 

Please re-read post # 12.      The answer lies within.       But hey, if you want to glass the deck first, be my guest.      You wouldn’t be the first to ignore my advice,and suffer for it.

My top tips for epoxy cut laps.

Masking tape on your glassing stands or it’ll stick, clean tape every time.

Timings as previously mentioned as soon as it’s not sticky.

Wallpaper seam roller to press the bottom lap down gives a much cleaner deck lam.

Put the 6oz on top as the resin will soak through it better

Got it. Thank you all very much! I really appreciate the help. And yeah Bill I just saw #12, makes perfect sense, thanks 

my first EPS and epoxy color lam I cut the laps, it bit me on the ass, I left the room for 15 minutes after cleaning up the lamination and came back to a larger than football blister starting along the lap, the blank had out gassed where I had cut into the foam on the firtst side. From that point on I made sure not to CUT into the foam for any reason, but did subsequent color lam’s by laying 3 layers of green tape on top of each other and after cure hit the lap with my die grinder. The portion inside the lap falls right out with no intrusion of the EPS. When I’ve finished cleaning up an epoxy lam, I puncture the wet lam where plugs or boxes would go to let it gas off, this way I have a point of least resitance.

This photo is a 12’0" 2.2 # White Hot EPS, Resin Research Qwik Kick, double 4oz. S top and bottom