Which cloth to use?

General Composites Discussions Composites Talk
#1

Some of you saw my solo seat cowl i made from fiberglass/resin.

It twisted under load from the spring, and also from being opened and closed. It was on a hinge with a latch on the oposite end.

I am making two or three new revised versions of that seat cowl. I am going to use poly resin with mat for the first layer in a female mold. Right now I have no way to spray Gel Coat… so sad but the truth. I was thinking of just using resin as the “gel coat” layer in the mold over wax and pva. I want to use mat so the cloth doesn’t make a transfer pattern on the side people will see. I’m probably going to sand the PER so it is smooth after the part is popped out of the mold.

My main question is, what type of fiberglass cloth to use that will help reduce twisting of the part? Is plain cloth a bad idea for this purpose?

Is there a way to roll gel coat into the mold or poor it in and even it out with the roller? I know spraying is the way to go, but i don’t have an air-compressor for the time being.

#2

If you are laying up small CSM part, then just brush your gel-coat into the mould. While using different materials will certainly resist twisting, if your part doesnt have the necessary strength, then its going to twist no matter what.

To reduce/prevent print through, use a layer of tissue over your gel-coat before laminating the rest of it. Finally I would say it might be a very good idea to make a few very simple parts, so you are familiar with the process and materials, before getting involved with things needing bonded in mountings etc.

#3

Ya also have to watch which way the fabric is layed up.
if you put 0/90 0/90 -33/33, you will have that 45 twisting it bad.
I layed up some Uni CF on foam strips. I wrapped it once in 45, and then the rest was 0 lengthwise. It is now like a twisted iron railing thingy.
I think that Fiberglass book goes over fiber directions.