glassing question

After all this years shaping/glassing i figured out that firts is bottom and after deck.
With all the boards i used the same procedure. First deck and second bottom.
Can anybody tell me why first is bottom?

Since there is less glass on the bottom you want your bottom layer to go under the deck side laps for strength.

Because you can hide the sloppy free lap in the crown of the deck.  Also hopefully ou spend more time looking at the top of the board.  Thats where the pinline and cut lap is visable.

And lastly, it isn’t always deck first.

i usually glass the decks first. easier to get the bottom nice and flat.

Mako’s answer is better than Every’s.  I will leave it like that for now. 

If you have two layers of cloth on the deck and you lay that down first then the bottom single layer over that my thought is even the tiniest sand through into the weave of the cloth of your single bottom layer would seriously compromise the strength of the board.

I guess if you never mastered a free-lap then of course they would be sloppy…  Hence the reason some use a bag all the time.  Laps “cut” or “free” can be easily hidden with proper hand laid technique.  Mako is correct.  So learn to use a squeege and  do a nice lap.  It’s technique that some never take the time to learn, so they rely on the vacum bag.  Vacum is a great and useful tool for some applications, but a crutch for poor laminating skills

Wow McDing, you sure told me


Mako’s second response was better than his first, but Mcding is the McKing of comedy.

For color reasons I just did a glass job with the deck first. Guess what? the glass job came out just fine…Give me a choice? The bottom is getting glassed first. With one layer of cloth.

It matters…do what works for you…Ray

There IS a real reason to select glassing the bottom FIRST.     None have mentioned it.         In the balsa era, the method was to glass the deck first.    There was an important structural reason that it changed.       I’ll discuss that later.     For now, think about it.

G-rat and McDing sure seem to be getting along well

Is rocker a factor in any way?

Shrinkage. Glassing the bottom first will have the tendency to reduce the rocker but since it is only 1 layer of glass will shrink less than 2 layers. the deck with 2 layers and more resin will shrink more but if the bottom is glassed first it has something to resist the pull, thus reducing the  “extra” rocker effect. Thus the bottom first glassing will be a dimensionally more stable board, since we are generally producing an unbalanced laminate when we make surfboards. So the board will end up closer to the shapers intended shape. I’ve found out the hard way with some flat sandwich panels how much an unbalanced laminate can warp a panel due the resin shrinkage. When using double bias top and bottom it is also important to flip the glass on one side to avoid warping. The more symmetrical about the neutral axis the better, thus the least amount of twisting due to shrinkage. Am i right Bill?  

A little long winded, but overall, yes.      The least change in the shaped rocker.      Well done.

Whatever you say Gollum.

If you want a good job do one deck layer, flip and do the bottom, then finish with the second deck layer, all in one process. Strong and doesn’t tempt rocker shrinkage, and make sure your fabric is layed out at 0/90.


For short boards what i do is (i always use UV resin):

1st: reinforce the deck with 4oz 3/4 tail to nose

2nd: 6oz cutlap deck lamination flip the board and push the cutlap into the foam

3rd: 6oz cutlap bottom lamination.

The only long board i did was:

1st: reinforce deck with 4oz 1/2 tail to nose

2nd: deck lamination - cutlap 6oz

3rd: bottom reinforce the tail (fin box) around 1.5’  - 4oz

4th: bottom lam with cutlap 6oz

5th: deck lam cutlap 6oz

6th: bottom lam cutlap 4oz

I wanna make another long a lil bit wider** 23 1/2’‘** instead 21 3/4’’ and 3 1/4 thick instead 3 1/2’’ for the shity waves we have in summer.

The laminatio it’ll be:

deck - 6oz+4oz and reinforce with 4oz

bottom - 4oz+4oz reinforce with 4oz


cheers Colin

Colin:  Ask yourself these questions:

Which is the most important aspect of surfboard design: outline, rail shape, fin placement, rocker?

Second:  Which is more affected by glassing:  outline, rail shape, fin placement, rocker?

There is an answer in there somewhere!  Just my 2c…