help: Fiberglass cloth- hard time wetting out
CB WK 18
Have been fiberglassing sides and bottom of plywood hull. Never had this
problem, seems real hard to wet out and get the air out. Alot of air pockets
come back after you lay them flat, Any ideas, using 6 and 10 once glass.
Thank You,
Chuck
Lew Hodgett
Don't know whether you are using polyester of epoxy, my comments are based
on epoxy.
1) Rough up the plywood with a disk sander and some 24-36 grit paper. You
need a surface that will absorb resin.
2) Coat the plywood with resin, making sure everything is completely wetted
out.
SFWIW, I usually coat plywood one day, come back the next, scuff it up with
disk sander, then lay glass.
I never try to lay glass over untreated plywood, it is too tough to keep
from getting "starved resin" areas.
BTW, are you using a laminating (low viscosity) resin? Makes a BIG
difference.
HTH
(Off to the boat yard to lay some glass on some plywood that was sealed
yesterday, before the rains come.)
--
Lew
S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: <http://home.earthlink.net/~lewhodgett> for Pictures
ProCareJax
Use a squeege and try to get as much resin (whatever kind your using) squeeged
off when laying the glass down initially.
Dont try to lay the glass down and filll the weave at the same time.
If this is what you're trying to do, you have too much resin on the surface and
the glass is wanting to float. Squeege it off, so the glass lays and adheres to
the surface and let it cure. Come back later with a second coat and maybe a
third for 10 oz. cloth and fill the weave (with the squeege) until smooth.
Another problem with glassing plywood (especially common with polyester
resins)...if you have "low spots" in your panels or if a large area is not
perfectly flat and true, it can cause the cloth to pull away from the surface
or in other words "bridge" the "null" or low spot due to the fact that
polyester shrinks as it cures and will taughten the glass fabric somewhat.
Again the fix for this is as above...just use a smaller squeege (to be sure
your squeege doesnt bridge the null) mix your resin a little "hotter" so it
kicks sooner and work to get your fabric bonded to the surface in smaller areas
at a time. You can fill later.
Hope this helps
Dave
Jim Conlin
less interested in wetting the glass. Warm the boat and your resin ahead of time
with heat lamps or otherwise. This will make the resin flow more easily. Don't
try to apply heat after the resin is applied. This will cause outgassing, driving
bubbles out of the wood's pores into your glass.
Jim
SteveC1280
things. It's hard to tell what the problem is without actually seeing it. If
some of the good suggestions in the other replies don't work, there could be
some other causes. One, if the cloth you are using ever got wet with water
(even if it's dry now), it will no longer wet-out with resin. Two, the heat
from the curing resin will cause the air in the wood to expand. You'll get
endless bubbles until it cools down or cures.
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Backyard Renegade
If you are having problems with the low spots and stuff, try putting a
little thickener into some resin and work that into those areas.
Another thing to remember when laying glass (in my limited experience)
is that it is easier to draw resin up through the glass than it is to
drive it down through, replacing air. What I mean here is when
glassing, I put at least 60% of the resin down before I lay out the
glass, and then brush or roll or squeegie the rest over the top where
needed. Note what the other said about the wood gassing. It is better
to glass when the temperature is dropping rather than rising, I
usually skin boats in the later afternoon if I have a choice.
Scotty
brian dixon
know the problem ... I just finished fiberglassing a 14' skiff (6oz bottom,
4oz sides). At first, I had the frustrating 'white bubble' problem too.
I'd wet it all out, it would look fine, then the bubble in the glass would
just pop up. I tried flattening it back down (various methods), but it kept
popping up. I tried cutting it with a knife to relieve stress and/or air
and then flattening it down, and it still popped up. I finally let it cure,
SurFormed it off, then patched it ... but I found a better way when doing
the rest of the boat!
The bubbles are causes by the glass cloth naturally trying to wrinkle, like
when you lay a blanket on the floor and there's a wrinkle in it. The epoxy
(I assume you are using epoxy) can force it down temporarily, but it'll pop
back up.
Here's how to prevent that problem: Lay out the dry cloth on the surface you
are glassing, using blue painter's tape (or other method) to hold it in
place. Wet it out with a dense foam roller (my personal favorite way) ...
starting in the middle FARTHEST from the edges. Continue to roll and wet
out the glass, moving towards the edge areas BUT as you go, use your free
hand to stretch the glass towards the edges. This will remove the tendency
to 'wrinkle' back up and form those annoying bubbles. If the glass ends up
with a big wrinkle all in one or two spots, usually near the edge or along a
curve, then don't worry. The rest will be flat. Cut along the wrinkle with
scissors and wet it out, one side at a time. I just let the two sides of
the cut wrinkle overlap. Using this method, the whole boat can be glassed
with no wrinkles ... it's purely a technique of making sure there's no
tendency to wrinkle and you it by making sure you pull out available slack
as best you can along the way.
At worst, you'll have a very very minor (1" or smaller) spot at the top of
the cut wrinkles that'll need SurForm'ing (or scraping with a cabinet
scraper).
Good luck!
Brian
"CB WK 18" <cbw...@aol.com> wrote in message
news:20011124111946...@mb-mo.aol.com...
@signgoeshere Tom Bloomer
After pre-coating the wood to seal it with epoxy and sanding the surface to
remove any blush, roll on a thin layer of epoxy. Roll the cloth on top of
the wet epoxy and brush it down with a wide brush. Pull the edges with your
fingers (wear gloves please) to remove any wrinkles and continue to smooth
it out. The glass will not wet out completely, it will have a lot of dry
white fibers, but DON'T add any more resin. Wait until the resin has set to
the hard gel stage - where you can still get your fingernail into it. Then
finish wetting the glass from the top. This usually delivers a very smooth
surface with no bubbles in the glass. If this method does not work, your
fiberglass is probably contaminated and you should find different cloth.
--
Tom Bloomer
Hartly, DE
Jtown2354
glass cloth, and then mix enough resin to give the wood a coat - but this resin
is mixed a tad warm. When the "pre-coat" has gotten a little tacky, I smooth
on the cloth and then saturate the cloth normally. This eliminates the
bubbling problem and generally works well on all orientations beit horizontal,
vertical or overhead. ---- Jerry / Idaho