Do you like frosting?

[CatBuilder]

Hey Boston... I'll answer down inline in your post in red.

Originally Posted by Boston

oh I read it but how is less absorbed simply because it is applied separately from the fabric



I can understand how it might help prevent starvation but I'm a bit baffled about two things
one would be the color differences I see in some of the pictures and the other is what dynamic is involved in less being absorbed

The difference between the two is pretty simple, actually. The darker one is the "frosting" my designer suggests. It is a mixture of neat epoxy and phenolic microballoons. He feels this mixture would make a better bond between the fabric and the foam. The lighter colored one is just plain old epoxy between the fabric and foam. The microballoons thicken up the epoxy, which makes for a different set of properties when wetting out the backside of the fabric against the foam.

the actual frosting is a coating you put on the core before you apply the cloth seems easy but I'm embarrassed to say I'm not getting the mechanical properties that make this so

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.

One place I do plan on using frosting is to hold the many sheets of foam together before laying up the fiberglass on them, as well as to fill in or level off any gouges, etc... You need to have a very uniform surface to do the fiberglass layup so as not to trap any air between the fabric and foam. I will use the microballoons to fill gaps anywhere in the foam surface, but not across all of the foam.

Hope that helps...



sorry to interrupt a fine thread but as I read along I cant help but feel like I"m missing something

ps
I've exactly no experience with composites so gimme a break on what must seem like a dumb question

[Boston]

thanks

now to go back and read through again so I know I got it this time

cheers

[rxcomposite]

Great thread! If not for Catbuilders incessant questioning, the issue will not be resolved. Even Rulebooks are in conflict with each other. Take a look at this.

DNV
Core materials with open cells in the surface, should
normally be impregnated with resin before it is applied to a wet
laminate or before lamination on the core is commenced.

LR
Additional flow coating is not to be applied in the foam core prior to laminating.


But Rulebooks are not inflexible. They ask for test if method deviates from the instructions, in this case interlaminar shear.

Which is what Catbuilder is methodically doing. He ask the right question and we learn from it. This is what boatbuilding is about.

[AndrewK]

Originally Posted by CatBuilder

One more question: Later, when I am done with this laminate for inside the hull and want to have a smooth surface, I use microbaloons to fill in the weave, of the triaxial, correct? Is this nice and waterproof? Do people ever add neat to fill in the weave, or is that just too expensive, difficult to sand and time consuming? Do people usually finish off the interior surface, or just leave it be? Is one layer of 34oz triaxial just "wet out" with epoxy waterproof without doing anything else to it? Or.. are there many little pin holes and places where standing bilge water will make its way into the laminate?

One layer will have pinholes, but this is not an issue with your inner laminate. You will not have water in your bilges.

When laminating you deal with the weave straight away not after the resin has sett.
You either use peel ply or trowel on a soft bog, like your frosting.

A lot of builders avoid peel ply regarding it as an additional cost. I dont think this is true if you take into account of the cost of additional resin and balloons plus the cost of sandpaper and your time for later on preparation peel ply is a winner.

Peel ply will also reduce pin holes and greatly reduce your resin run out as well, even with your build the deck part will be vertical as well as some of the bilge.

Another option to reduce the trapped air between the warp tow is to lay it so the +/-45 fiber is on the foam and the 0 deg fiber with the large gaps is on top. Check with Kurt that he is fine with this orientation.