Damp fiber glass cloth


Today I opened the cardboard box that contains my fiberglass cloth.The box was on the floor in my garage. The glass as usual is wrapped aoround a cardboard tube and then covered in paper. Anyway…I noticed that the outer paper and the cardboard tube felt quite damp. 

I have to assume that there is a certain moisture content now in my cloth. I’ve put the cloth into my boiler house which is a nice warm dry environment. 


Do you think a couple of weeks in this warm dry environment will remove any moisture. 

Will this cloth be ok to use with Epoxy.

Does water ingress leave staining on the cloth that will only show when lamination starts ?

Help required from the glassign experts







Hi Brian -

I glassed a board using the glass from the very end of the roll.  The last few wraps from the cardboard tube left a ghostly semi-opaque 'zebra' stripe kind of thing in the laminate.  I suspect that at some point the cardboard tube had absorbed some moisture that somehow affected the finish of the cloth.  Other people on Swaylocks have suggested moisture-affected cloth as a culprit in visible weave situations like glass-on fins, etc. 

It will probably be OK to use but just for kicks you might take a sample of cloth that hasn't been in contact with moisture, dap some water stripes across it, let dry and laminate over dark wood.  I think you'll see what I mean.  It probably won't be as obvious on a white or clear board.

Some places ship their cloth rolls wrapped in plastic.  I suspect there is a reason.

ADD:  I just found this on 'Laughing Look' wooden kayak website...

"Fiberglass cloth is coated with a special sizing to make it compatible with epoxy resin. This sizing is sensitive to water and can be damaged or removed if water comes in contact with it. The result will be a glass weave that looks white. Be careful not to have water on a surface or on your hands, that could come in contact with fiberglass cloth. Be wary of a "sale" on cloth that might be water damaged."

Unless it's a full 100+ yard roll, you should be able to pull out any moisture by putting it in a fresh (dry) box with a dessicant (I believe it's calcium chloride). I guess you've figured out that in the future you should store your cloth in a better place.