Sanding top laps on sprayed blanks

So I did a spray job (solid bottom, wrapping up and around the top rails) and laminated the bottom. No problems.

However, I always sand the wrapped lap on the top to make it nice and smooth/feathered into the blank before lamming the deck. This time, I was very hesitant to sand the top lap because I was worried I would hit the spray and ruin the clean line. As a result, by top lam was a bit bumpy which translated into a tough sanding job.

I know this is a pretty common spray job, so how do you guys get the laps clean without damaging the spray? Do you baste the area with resin to protect prior to sanding?


Either that or try to make your lap as clean as possible (i.e. no strands…), then when cured, gently push the cloth into the foam with a wallpaper roller. Also, cutting the lap so it fully covers the spray would help.

cut lap at the edge of the  paint...

Cutlaps to the line or free-lapping over the edge of the paint line may be kind of tough because my boards are usually pretty wide (over 20") and in the center of the board it’s not possible to get very wide laps unless I go with super-wide SUP cloth. Either that or I need to spray a narrower band on the deck to make sure my laps can cover.

Love to hear if there are any other tricks.

Wondering if I can baste the sprayed foam with UV-Cure poly to save time? (on a pu blank with an Epoxy lam and hot-coat).

As stated above; baste.   Cutlap to the paint line or freelap beyond the paintline (next time).     This time use the seam roller and press it down.  If that doesn't take care of it, baste and grind the laps verrrrrrrry carefully.

On solid paint jobs  you can buy yourself an “insurance policy” by pasting the lap line with laminating resin and  a 2" or 3" brush before trying to sand.  Do not use a seam roller or you will form a crack where the glass meets the foam.  Furthermore when the painted board is a solid color, if one cuts the bottom lam lap, it will show as a crappy looking paint when finished.  Also don’t even think about pulling any wild hairs or you will pull up the paint.  That is the basics.

And do not even attempt to fill an eps foam blank with polyester resin- even if its sealed.  Practice good craftsmanship and take your time its not a race.  Once the board is finished your judged by the results- every time. Bad craftsmanship will ruin you before you start.

Just looked at the picture and the board looks good! I thought the board was a solid color, so the others techniques work.   On something like that you can just leave tape on and glass and then cut and roll.  Or if your worried about the tape bleeding because you did not secure it properly, just make sure you exceed the paint with the glass lap. Normally a 20" wide board can be fully overlapped easily with 27’ cloth on something like that.   Nonetheless, the board  looks good.  

I just did one with painted foam and was worried about just this issue. I found that where my resin had gone past the lap onto the bare paint (which was most of the way around) I had little trouble sanding through to the paint. Next time I will be sure to baste or brush coat the lap edge with resin. I would be curious to know how to avoid the stringy messy sections and  get a cleaner free lap.

Its in the technique,  try to finish your laps going lengthwise, instead of pushing toward the center of the board.  Also if you have the time either weave the strands back in with you fingers, or cut them, or pull them off, before the resin gels.  I should add there is a deftness of touch that comes with experience, for if you push too hard you get air and too soft you get puddles.  Use one hand to lift the board at the ends and clean up mess with the other.  Visually check the whole rail when through. and do not settle for good enough.


    Howzit jamie, When doing free laps just pread excess rein past glass ver paint just that simple and with cut laps just do the baste after you cut the glass. But you still have to be careful since you can snag the resin and it will pull some of the paint off. Be careful,verwy careful

Hi Jamie,

I always baste my free laps with hotcoat (not too much wax in styrene added as too much can react with paint). I go to about 2 inch out onto deck and about an inch below lap onto cloth. I then sand off with ease leaving a perfect feathered edge.



PS your board looks great...would like to see finished pictures