White Spots

[tomherrick]

Starting again with my lamination. In accordance with guidance from U.S. Composites, I heated the shop to 85-degrees; the fiberglass and the boat were at that temp; the epoxy was up around 90-degrees. Just before mixing the epoxy, I turned the heat down to 80-degrees to prevent outgassing from the plywood core. I rolled a coat of epoxy on the plywood (which already had one cured coat) and let it get tacky. Applied the 1708 dry to the tacky epoxy and wetted it out until it was totally transparent, then applied peel ply. This morning, I find small white spots - apparently, epoxy-starved fiberglass. The glass is well adhered to the plywood; there are no bubbles, it's just drier than I'd like. This, after thinking I might be putting on too much epoxy. I've included a pic below to show the worst of it.

Suggestions???

[Herman]

A bit on the dry side. Perhaps some porous spots in the first coat, perhaps some humidity or moisture in the fiber.

[tomherrick]

Thinking about rolling on a light coat, let it get tacky, wetting out the glass on the bench, then applying it to the boat. At your suggestion, I'll likely recoat the remaining plywood core material as further precaution against porosity. I thought I had that covered, but perhaps not well enough. Thanks.

[tunnels]

Originally Posted by tomherrick

Starting again with my lamination. In accordance with guidance from U.S. Composites, I heated the shop to 85-degrees; the fiberglass and the boat were at that temp; the epoxy was up around 90-degrees. Just before mixing the epoxy, I turned the heat down to 80-degrees to prevent outgassing from the plywood core. I rolled a coat of epoxy on the plywood (which already had one cured coat) and let it get tacky. Applied the 1708 dry to the tacky epoxy and wetted it out until it was totally transparent, then applied peel ply. This morning, I find small white spots - apparently, epoxy-starved fiberglass. The glass is well adhered to the plywood; there are no bubbles, it's just drier than I'd like. This, after thinking I might be putting on too much epoxy. I've included a pic below to show the worst of it.

Suggestions???

When you put the peel ply over the top of your glass layer did you wet out the peel ply and roll it the same as the glass ? the peel ply also needs to be wet out !! just relying on the resin thats in the glass is where the starvation could have come from !peel ply should look shiny with resin when its rolled out properly with a steel laminating roller !!
If it is starvation try brushing a little slightly thined resin over the top of what there i could simply fill the spots with resin and they could simply dissapear !!most times those starved patch will still be soft and they are pourus so the brushing will fill each hole and it will all go hard

[tomherrick]

When you put the peel ply over the top of your glass layer did you wet out the peel ply and roll it the same as the glass ?

Nope, I didn't. I just pressed it on with my laminating roller. There were places where it wasn't in contact with the glass/epoxy lamination. Perhaps where it was in contact, the glass got starved.

[tunnels]

Originally Posted by tomherrick

Nope, I didn't. I just pressed it on with my laminating roller. There were places where it wasn't in contact with the glass/epoxy lamination. Perhaps where it was in contact, the glass got starved.

Ok explains all ! Yes its resin starved !!
When you use peel ply always use a little resin to roll it down then roll it out with a steel roller it should look shiney on the surface !!
In actual fact the glass was short of resin any way and even without the peel ply it would have happened !! Never scimp on resin when wetting out your glass . I always use a short haired paint roller to wet out with and also to roll down the peel ply imediatly after wetting the glass !! make sure the glass is well wet out and the peel ply will tell you if theres enough resin on the glass as it will look wet and a little shiny on the surface then its time to use a steel roller !!if its not shiney any where apply a little more resin with the paint roller !!
Paint rollers are much better than using a brush as they even out and mop up any wet patchs and wet out the dry places a 4 inch roller is really all you need or it you are doing a big area a 6 inch roller is heaven !

[tomherrick]

I'm thinking the glass got it from both sides - the plywood may not have been as impermeable as I'd hoped and the peel ply wasn't wet out as you describe. A double whammy...

Getting ready to complete the first lamination layer tomorrow. Lots of prep on the plywood starting early-thirty...

I'll let y'all know what transpires.

Thanks

[CatBuilder]

I think that last post is probably it. Plywood is pretty thirsty and the peel ply drinks up a bit too. Probably got it from both sides.

There should have been a very thick film (dripping wet, not like painting) on the plywood before you stuck the glass, then wet the glass out from the front/face. Then, I suppose you do as Tunnels says. I tend to have very wet, sopping glass on a hand lamination and the peel ply sticks right to it without wetting the peel ply, but Tunnels method sounds pretty good.

[tomherrick]

I believe you all. Funny thing is that all the writing and video I've reviewed warns against using too much epoxy - I mean all of them. I thought I was overdoing it last night with the epoxy, but apparently not. I also believe the stuff I've read and viewed; it's all in understanding the balance.

Thanks again. I'll post the results.

[tunnels]

Originally Posted by CatBuilder

I think that last post is probably it. Plywood is pretty thirsty and the peel ply drinks up a bit too. Probably got it from both sides.

There should have been a very thick film (dripping wet, not like painting) on the plywood before you stuck the glass, then wet the glass out from the front/face. Then, I suppose you do as Tunnels says. I tend to have very wet, sopping glass on a hand lamination and the peel ply sticks right to it without wetting the peel ply, but Tunnels method sounds pretty good.

If the weave of the glass and or the peel ply looks dri it will be so add a little resin . just till its shiny thats all . Always remember resin shrinks a little when it goes hard even epoxys! polyester is the worst for shrinage .

[CatBuilder]

Originally Posted by tomherrick

I believe you all. Funny thing is that all the writing and video I've reviewed warns against using too much epoxy - I mean all of them. I thought I was overdoing it last night with the epoxy, but apparently not. I also believe the stuff I've read and viewed; it's all in understanding the balance.

Thanks again. I'll post the results.

Yup. My designer beats it into your head over and over. He says a resin rich layup is not only much heavier, but it's much weaker. He's right, up to a point, and it looks like you reached that point.

I had some struggles in the beginning too, but found the right balance after a while. I slop it on heavy under the cloth, then wet out the top of the cloth.

I have completely given up on peel ply with hand lamination, since you can have a lighter boat by simply filling the weave with some fairing bog afterward (assuming a non-structural /non-bonded location on the panel).

Makes all of this stuff alot easier and I am then able to use a plastic squeegee to get every bit of air out from under the laminate. Took a lot of trial and error, but with the 34oz triax I am usually laying down, it is the best and lightest hand laminating method.

Some experimenting of different techniques will help. If those spots in the picture don't wet out from above, I'd suggest grinding them and patching them if you have any worries about future delamination.

[Herman]

For your next part, which already has 1 layer of epoxy on: pre-roll the (already impregnated) wood with a thicker epoxy brew (fumed silica/aerosil/cabosil added) to yoghurt or even mayonaise consistency. Roll it on in a thin layer. Then stick the glass to it, and impregnate the glass. This also prevents the wood from drinking too much.

And indeed, laminate the peelply as if it was just a layer of glass.

[tomherrick]

So far, so good - so far... I decided against using the peel ply for this lamination to help avoid the problems I experienced earlier. The glass on the plywood core is transparent and, so far, staying that way. If it starts to go white I'll add some more epoxy, but I doubt that'll happen.

I'll save the peel ply for subsequent laminations (six in all) when I'll use vacuum to hold the glass down tight against semi-sharp offsets.

[tunnels]

so what happened ??

[tomherrick]

It's working well, even on the vertical sides. I rolled on a bit of epoxy, tipped it off to rid it of bubbles and let it get tacky, wet out the 1708 on my workbench, slapped it on the C-Flex hull and worked it with a flexible drywall knife and laminating roller until all the white spots were gone. I didn't use peel ply for this go around. Have to be gone for a week. Upon return I'll do whatever grinding is necessary then develop my vacuum lamination process and get on with the remaining five laminations of 1708 for the hull exterior.