What happened during the lamination?

General Discussion
1

Today i glassed a low density eps blank with epoxy, when the resin started to get tacky depressions apeared on the blank, looked like under vacuum.

It is 1.2 ppcf ( 20kg/m^3) eps around 140 l Volume.

2 layer of 6 ounce glass

Epoxy with 30 min potlife

glassed the bottom yesterday in nearly same conditions, under the roof, 25 °C.

First i was thinking about pressure, and drilled the gore vent open, but this vakuumed look makes me think its something different.

Can anybody give me a hint ?

Thanks

Jasper

 

2

Hi Jasper-

Sorry to hear of your troubles. 1.2 PCF foam and 25 degrees C should be pretty good for epoxy. Could I ask a couple of questions please?

-Was the blank sealed in any fashion, spackled, or painted?

-How was blank ‘dusted off’ before lamination: shop air, brush, rag, ball of tape?

-Any solvents involved? Wiping down with alcohols or something mixed into the epoxy like xylene or Add F?

  • Were temps rising, falling, or steady? Was blank equal to or warmer than ambient air temp?

-Do you have a guess at cloth weight on board versus mixed epoxy weight? Checking for dry lam here…

-Do you have a pic of a trouble spot?

-Surfboard glass and epoxy or other types?

 

 

3

Can you post some pics?

4

Hi J, thanks for the fast response!

i was just outside to take a picture and upload it, but i have some trouble getting the mac of my girlfriend talk to my microsoftsmartphone…

the blank was not sealed, but painted with liquitex spraycans, a very low solvent acrylic paint.

sprayed the whole blank two days ago, just slightly, and laminated with tinted resin.

No wiping or additives, i just brushed of the blank slightly after sanding carefully the laps 100 grit, same procedure as the last time.

Temps are kind of steady, but my rooftop is semitransparent, and indirect light was shining on the problematic side.

Its not a specified surfboard resin and glass, but its a highquality resin from an local manufacturer that turned out to be good over the last boards.

glass is 160g plain weave silan ( kind of 6 ounce)

During lamination i mixed about 1200 g of epoxy in two batches, one after the other, procedure was

lay up both layers of cloth , empty  first batch of resin on the middle , spread cloth nose to tail and then to rails

then cut the cloth, mix second batch of resin, and proceed wetout.

blank is about 10 feet / 31 inch wide, and pretty thick, SUP so i guess about 5 squaremeter 6 ounce total.

I try with the pictures now ,

Thanks,

cheers

J

5

Sorry  for the size of the picture!

2000×3552 2.31 MB

6

Just to be sure, have you used this resin on EPS before?

7

another pic

3552×2000 2.48 MB

8

Hi newschoolblue, yes i have used the resin before without any problems.

All always had some trouble, but that was always caused by myself.

9

When you sprayed the liquitex paint, were your passes along the length of the board, side-to-side, criss-cross, . . ?

Have you used this resin over that paint before?  If so, is it possible that previous paint jobs were thicker/heavier than the current one?

Just trying to understand if anything changed in this build versus previous ones.  How many boards have you built?

10

Jasper, see if you can locate the Material Safety Data Sheet for the paint.

The one I found in the US can be up to 30% ethyl alcohol and 5% acetone.

The paint may have skinned over and the acetone reaction happened underneath.

Pic is of EPS treated with a couple drops of acetone and 1/2 a cap of DNA. The DNA side did not melt but the foam feels ‘damp’  20 minutes later.

784×523 108 KB

11

Yeah, you maybe right, could really be the paint…

@newschoolblue: i applied the color kind of cloudlike, starting with darker colors , than lighter colors… sprayed very light multiple layers.

i made some test on foam , and had the same procedure on both sides …

the bottom went well yesterday…, maybe its a mix of solvent in the paint and sunlight?

problem occured only on the side that was less shaded.

@jrandy : i checked the Data sheet, your right… many, many thanks for your effort,  i think you found the answer.  I just made a test on some leftover foam,

looked for any destruction, and thought i was good to go… This is board number 8, i have no real experience, cause i try something new everytime so there is always enough room for error. This time i am really a little bit sad, cause everything else went really well this time, and the board is kind of a present…

Do you think its also a sructural problem? Most of the bad spots will be covered by a cork patch, but i think glass is ment to lie straight?

 

12

The bottom - no troubles there.

2448×3264 1.5 MB

13

If the problem has stabilized and is not continuing to get worse, then I would fill in with resin or resin and glass, sand everything smooth, and cover with cork. If problem continues to get progressively worse, then you might have to cut your losses and toss it.  Just my opinion.

14

Its not getting worse… had the same thoughts, i will fill it where its needed and focus on the next project.

Thanks for caring.

 

15

I never ever spray anything from a can on to raw eps. The propellant in the cans will eat your foam, the paint will eat your foam, the can just looking at your blank will eat your foam. If you must spray eps do it with acrylic water based paint from a spray gun…but  the best eps board is a white eps board.

I gotta ask you, if you are doing a blended sky cloud look…why not just do it in the resin lam? All that muddied color, if that’s what you were going after would be easy in a lam.    If not I always do my color work on top of the hot coat before the gloss spray.  

Live and learn

16

 live and maybe learn

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But i think i got that now.

18

I’ve got no first-hand experience but I talked to the ppl working at the artist store that sell all kinds of different paints etcetera and they told me that there are not yet any brand that has a solvent free spray can.

Apparently, it is too expensive to make a can out of stainless steel and that’s why they have to add different things to the paint that also makes the can inside protected from rust.

 

19

Yes you are right… on some spraycans they say its good for eps, but i will be more carefull now. it looked good on the testfoamchunks and there was no sign of trouble befor glassing…

better take a different path.