Contact   Imprint   Advertising   Guidelines

Dry spots

here you can exchange your experience and datas about your home build boards


Kerry Baragwanath
Rare Poster
Posts: 8
Joined: Sat Jun 18, 2005 12:14 pm

Dry spots

Postby Kerry Baragwanath » Sun Jun 19, 2005 7:39 am

I vaccum bagged my first board a few days ago (yeah baby yeah) & when I removed the peel ply there are one or two small "dry spots"

- How do I prevent this in the future? (My bag pulls between -0.6 & -0.9)
- How do I fix it now?

Thanks in advance.

Kerry

zfennell
Very Frequent Poster
Posts: 972
Joined: Wed Nov 20, 2002 1:00 am
Kiting since: 0
Brand Affiliation: None
Location: rhode island

Postby zfennell » Thu Jun 23, 2005 4:21 pm

hi.
what units are on the vacuum gage?
I'm assumng you mean .6-.9 atmospheres or bars

was the glass completely wet out before sticking it in the bag?
do you check the bag for any leaks?
(how long can it hold vacuum if you turn off the pump?)

did you use a breather, and did the vacuum seem to pull the bag uniformly around the board?


the vacuum doesn't actually move the epoxy much.
it just squeezes the excess through the peel ply.
so if there are any dry spots before the bagging, there's a good chance it will still be there when the resin kicks.

.9 bar is a little on the high side.
too much vacuum can make the laminate a little dry,
excess vacuum can draw some air out of the core or solvents out of the resin.
these may be caught in the resin.

leaks in the bag suck in air that has to go somewhere.
mostly it travels around the board, but not necessarily.

as far as the fix goes:
there is probably enough cured resin, that you can no longer completely
wet out the dry spot.
I would sand through the area in question and laminate a small
overlapping patch of glass.

if the spots are less than 1"diameter,
the repair is more for cosmetics than structural need.
but you never know.

no worries,
-bill

Kerry Baragwanath
Rare Poster
Posts: 8
Joined: Sat Jun 18, 2005 12:14 pm

Postby Kerry Baragwanath » Sat Jun 25, 2005 7:15 am

OK questions first...

Yes - Bars...
Yes it was completely wet out
Yes there was one leak... I dont seem to have a dry spot where the leak was.
I have managed to get my bag system down to about 3 cycles every ten minutes.
I used peel ply only... and no it didnt pull completely uniformally (I think have a solution for this). To improve circulation in the bag I was thinking of taping a thin bathroom towell to the deck i'm not laminating. (I'm doing a two step laminting process in a plastic tube)

The biggest dry spot is right on the tail!!! About the size of a box of cigarettes.... @#%$. I used tacs on the other side of the board to attach the peel ply to the board and one of them pushed through (the board is 6mm a the tips) So this was the cause. Do i really need to sand all the fibre away and use a patch?? Wont the bond and material be too weak?

There were one or two other small dry spots (surface only) which I covered with a hot coat.

Thanks for he advice

Kerry

zfennell
Very Frequent Poster
Posts: 972
Joined: Wed Nov 20, 2002 1:00 am
Kiting since: 0
Brand Affiliation: None
Location: rhode island

Postby zfennell » Sun Jun 26, 2005 1:09 am

hi keri,
regarding the fix:
It's not likely the dry spot will ever be structural, because you can
no longer wet out the entire laminate.

so you really have nothing to lose by sanding back to something clean
and sound.

if the patch overlaps the original lam. by approx. 1" all around
it should be able to carry sufficient loads.
but, since the dry spot is in the tip. there probably isn't much stress there
anyway.
so just about anything should work, as long as its water tight.

-bill

Kerry Baragwanath
Rare Poster
Posts: 8
Joined: Sat Jun 18, 2005 12:14 pm

Postby Kerry Baragwanath » Sun Jun 26, 2005 6:25 am

Thanks for he advice Bill, I'll give it a go :thumb:

crabman
Medium Poster
Posts: 158
Joined: Mon Dec 05, 2005 4:44 pm

Postby crabman » Mon Dec 19, 2005 7:09 pm

To stop dry spots roller out the peel ply when wet before applying the breather. You should not have to staple anything .http://www.racingfinish.co.uk

User avatar
sq225917
Very Frequent Poster
Posts: 8743
Joined: Tue Nov 05, 2002 1:00 am
Kiting since: 0
Brand Affiliation: BestKiteboarding.com

Postby sq225917 » Mon Dec 19, 2005 8:29 pm

dry spots £10 says you have concave on the base.....


Return to “Board Builders”

Who is online

Users browsing this forum: No registered users and 2 guests