hand lay up of coracell m foam

so panel is cured,glass goes down nice and flat only the stiching is still up. how do you treat this? can i just sand it down?

 

Congratulations on a good laminate.

The weave cannot be sander. That would reduce strength!

That is what peel ply, a shiny mold or bog is for... Looks afterward.

 

the glass is full and flat its the stiching that is still proud of the surface.you can feel it when u run your fingers across, very sharp.I guess i have no choice but to sand it.is this normal with stiched glass?or should i have had more resin on it to bury the stiching?

 

Stitching sanding will not be a problem. It might be easier to wait a day till it hardens up, or you will just clog up the sandpaper. Experiment with 'wet and dry' paper and water as well, it creates a great smooth surface.

If its not a major drama, I think you would benefit from experimenting a bit with using peel ply.

There is nothing more satisfying than ripping off a length of fabric and seeing a uniform, flat "not needing sanding" surface largely free from amine blush.

Putting it on is also very satisfying too. Being able to squeegee the excess resin easily to the edges or onto unfilled areas to produce the ultimate best resin/glass ratio is a great benefit. combination. Used wisely, it will save a lot of sanding, and potential weave damage.

 

use peel ply !!

You have two choices use peel ply and have a smooth surface when its hard or get the material with a very thin lite chopped strand and roll it down nicely . Peel ply would be my choice !!

 

yes agreed,its the way to go.peel ply ordered.

i've been playing with petg plastic film .020 it has produced amazing results.
i went to the fabric store here to find ripstop for only 16$ a 2^m.there was no choices .yowzaa ,cheaper to just order online and get the right suff.

Thanks all, i think i'm gonna be happy with the end product.

 

Peel ply !!It is there to help you !!

Just about every post to do with glassing i am always pushing the merits of using peelply . Its not only to give a good finish it helps to compress the glass, draws out any surplus resin and if yu have the right stuff it easyer to see any bubbles within the glass lay up . Just make sure your peel ply has a semi wet look all over when you finished before you clean up and leave !!
The other thing is if you leave the surface for a length of time ,like weeks and you want to carry on glassing again Simply tear the peel ply and start glassing again like it was yesterday !!. just a quick scuff with 60 grit and ready to go !!most of the boats that get a painted finish inside its heaven ,just leave it there till you finished everything else and then tear it off and all the rubbish goes with it and you have a 100% clean virgin surface ready in minutes !!no grinding required !! and that alone is a saving of everything associated with the dreaded grinding jobs and clean up after !!

 

Thanks all again your advise has been helpful,
on the topic of peelply,i have the petg plastic film and can get locally for cheaper then peelply.the tests have been good and since it can be reused i think this is better for me.i no the flat shinny surface is no good for secondary bonding but i just plan on painting after anyway.also for bonding or tabbing in parts i can just sand with 36 grit yes?this should give enough for the goo to stick?

back to somemore tests,this was done with some thickened resin first and stiched biax tape.im getting the same result the glass is not sticking 100% to the foam some spots yes but some are coming off clean and in some spots the layers of glass are seperating.
a pic



not sure why?just the way the foam is?

 

Just to cover all bases, but I assume you are not doing any surface preparation to the foam itself ? (I am wondering if there is some sort of patchy contamination of the foams surface. Those areas look uncomfortably large for my tastes too.

Its hard to tell from the couple of pictures what is separating from what - but is the thickened epoxy not sticking to the foam ? The sections of fg cloth in the photo's don't seem to be wetted out - maybe its the photo but I would not expect them to be separating strand by strand if they were. Normally when torn, they come off in big sheet.

It might be worth trying a small bit of woven cloth over 16oz weight, and see if the problem persists with a different weave of glass.

The other thing that comes up from time to time on the forums, is making sure the 'size' (cloth coating) is compatible with epoxy. i understand that some 'sizes' are designed to dissolve in polyester or vynilester, and don't work well with epoxy.

 

That's no good at all. Those pictures show a poor wet out. You missed a huge spot with resin on the initial loading up of the foam. Or, you had an enormous bubble you didn't work out.

Fiberglass should go completely clear when wet out, with a greenish hue when many layers of glass are used. Otherwise, totally clear. That picture you show presents a non-clear patch of glass that you should have fixed during the lamination.

How did that happen?

Rwatson is right. Though exceedingly rare these days, there are certain binders on cloth that are not compatible with epoxy.

That is not something you could even trust to walk on, nevermind a structural part of a boat.

Very strange stuff.

Why do the other parts we see in the background of the pictures look properly laminated?

 

It might be worth reading this thread - ("frosting" is the thickened layer prior to the epoxy)

http://www.boatdesign.net/forums/boat-building/do-you-like-frosting-35889-4.html

One comment made by catbuilder

"I didn't get it either... which is why I had to make up these test samples. The idea of the test was to see if the frosting (epoxy and microballoons) was any stronger at holding the fabric to the foam than just using neat epoxy. The tests seem to show no advantage to using the frosting. Certainly, it is much more difficult to mix up frosting compared to just using neat epoxy, so I'll be using the neat now that I know there is no difference in adhesion between the two methods.

The voids you see are because I didn't roll these test samples out well (or at all, actually) and barely squeegeed it. The voids are in both and don't seem to have anything at all to do with the "frosting or not" question."

 

i'll check my supplier.

thanks

 

thanks but the cloth was wet no bubbles i worked the surface well with my spreader.the other parts are my first test again no bubbles veery flat they also have the same problem with the glass not sticking.

so the 18oz WR had the same problem,the6 oz wovin e glass same problem and the 12oz stiched 0 90 same thing.all three now have been tested against the foam.
maybe after i wet out the cloth i should let it sit for a minute then add somemore?

 

It's hard to guess what happened, but what I see in the picture is absolutely 100%, dry glass that was not wet out for some reason or another (could be lots of things).

If it's wet out, it's not white. If it's wet out, it also cannot separate from the weave and exist as a single strand of Uni like you have in the second picture sticking up. That's dry glass that's not wet out.

Are you using enough epoxy? Don't be shy with it. You need to slop it on there.

Something strange is going on. It shouldn't be this hard... definitely check with the supplier.

 

another pic of a piece i hammered it cracks,and the edges of the glass lifts here i was able to lift up the strands of 45 without effort.