For windsurf repairs the 'Board lady' shows many times the use of a vacuum pump + bag to get the divinycell firmly onto the EPS core, but does not show a vacuum pump being used for the final carbon/glass layup that goes on top of the divinycell.
For those that have a vacuum pump, do you use it (and bag + breather + PV film + peel ply) for the final top layers of carbon/glass on a repair? If you do use a pump, what sort of pressure do you have it on during this stage?
I have asked this question in my other post:
www.seabreeze.com.au/forums/Windsurfing/General/Isonic-repair-materials--2?page=1#19
but I feel it is buried in all the other questions I have asked!
Depends on the size of the repair, for smaller stuff, I tend to just use plastic taped as tightly over it as I can, then a layer of mattress foam with a heavy weight on top.
I have my vacuum set about 1/4 to 1/3 atmosphere, (or "fair" on my ancient automotive vacuum gauge)
Don't vac the laminate over the divinycell.
Using good squeegee technique it will be wet out enough without excess resin.
I agree with decrep, no need to bag small repairs, its just added hassle. I use the bit of removed divinycell to put over the new bit, so the curve is right and it sits proud of the deck thus making the taping / weight addition easier. Good tight taping with plastic masking tape can easily add as much pressure as light vac bagging.
I also think many people use too much pressure, I did a wood laminate on a surfboard at 4" Hg yesterday - bloody vac pump failure - and it still sucked resin thru the wood. If everything fits right you don't need 10" . Just like the girls tell me....
Thanks, knowing this will make the repair easier. Just need to make sure I'm careful with the amount of resin and use that squeegee to my advantage.
If you want to build light, use the vac bag. Vacuum consolidates any repair well also. I use vac for everything.
0.3 bar is plenty of pressure. 0.45 bar max.
Too much pressure and you can lose the rocker line when building a board.
For peel ply I use 'ripstop' dressmaking nylon (used for lining in suits etc).
Breather is garden shade cloth.
Low cost and locally available.
Awesome - so I can do it either way!
It made sense to me if you have a vac pump then why not use it, it is how the board is made in the first place.
For small repairs and glassing on top of the D-cell it will be a toss up for the extra cost and hassle of using the pump VS the few grams of weight saving on the final laminate.....but I get it now that with good technique either way will result in a repair that will last.
I converted some of units of measurement for reference:
0.30 bar = 8.9"Hg
0.45 bar = 13.3"Hg (Maximum)
1/4 atmosphere = 7.5"Hg
1/3 atmosphere = 9.0"Hg
The 'board lady' suggests 7" to 8" Hg for a D-cell repair and its nice for a beginner like me to know that everyone is in that ball park.
Thanks for the tips on breather and peel ply alternatives.
As a beginner I used actual peel ply and breather as I didn't want to second guess my self. On my first practice, I left out using perforated release film (I thought peel ply was water proof - which it is not! ) and way to much resin got drawn out of the laminate.
I used perforated release film on my actual repair and it worked a treat!
Do you have a substitute for perforated release film? use a vacuum bag and punch your own holes in it?
Select to expand quotesrtgumbee said..
Thanks for the tips on breather and peel ply alternatives.
As a beginner I used actual peel ply and breather as I didn't want to second guess my self. On my first practice, I left out using perforated release film (I thought peel ply was water proof - which it is not! ) and way to much resin got drawn out of the laminate.
I used perforated release film on my actual repair and it worked a treat!
Do you have a substitute for perforated release film? use a vacuum bag and punch your own holes in it?
I put the ripstop nylon straight onto the wet laminate, shade cloth on top (as resin absorber), plastic sheet on top, tape it all down, more shade cloth (as breather) then into the vac bag. The nylon does the release film job and peels off the cured laminate.
When buying the ripstop I makes sure I can breath thru it and that it doesn't rip easily. Had some once which tore as I peeled it off which was a pain.
I have a theory you should use a non "wicking" breather, I think Te Hau's shade sail cloth fits this category. I use poly quilting wadding.
I think they make perforated film for a reason. It is more "flat bits" than holey bits. Shade cloth is the other way around.
Peel ply is not needed unless you are going to laminate over it - all it does it make the resin surface rougher to avoid sanding.
Perf film, followed by a synthetic absorber like thin wadding (6-8mm ish) to pick up the excess bleeding thru the perf film and it also acts as a breather. Seems rather simple to me
