Stain on fiberglass cloth

[Rod Tait]

Is there any product that can remove a small stain on clean fiberglass cloth before it is used for clear coating. Will any attempt also damage the sizing and leave a mark anyways? Customer may have a small spot of blood on the cloth.

[johngsandusky]

I'm not a fiberglass expert. I've always thrown away discolored cloth, but I would think it's very resistant to damage. Soak in cold water first like you would any fabric for blood stains?

[Todd Bradshaw]

The volan sizing which is the most common one for fiberglass cloth is water soluble. You would probably wash it off with most anything, leaving an area which is far worse than what you have.

[Mike Dawson]

As Todd said the sizing dissolves when it becomes wet, it's there to hold the glass fibers together and aligned until you apply the resin. It will stain if it gets wet. I worked in the composite industry for 20 years and still have about 1/2 of a roll of 48" wide chopped strand mat that was headed for the dumpster after getting a little bit wet on one side. It leaves a milky white stain in the layup when used which doesn't bother me but it would not go well for a clear coating. The best you could do is cut out the damaged area and patch in with good glass, your skill level would determine the success rate.