Cleaning fiberglass tape/cloth-denatured alcohol

[bluedog225]

I've got a small stash of fiberglass tape of various weights that has been lying around the shop for years. I should have stored in a plastic bag but didn't.

Now that I finally need it, I want to wash the dust and crud off of it. Not grease or oil, just grime on the top layer.

I was debating using warm water and dawn, rinsing, then immersing in denatured alcohol and letting dry.

Any drawbacks to this approach? Should I be using something else? I'm looking for clean cloth with no residue from the cleaning.

Thanks

Tom

[pipefitter]

If it's just dust, it would be inert in epoxy. Think of all of the powders that make up various thickening agents. At most I would just hit it with a gentle blast of compressed air, or, stretch it out and use the dust brush with the shop vac maybe.

[AstoriaDave]

Yeah, don't manipulate it any more than you have to. The stuff is poorly attached to itself. Test a little bit of the exposed portion to make sure none of the dust is oily (epoxy-saturate it onto some wood, cure, and then try to pull it off). Otherwise, dust in a woodshop is benign.

[GRussell]

A rep from System 3 (I think) told me that 'glass cloth is coated with something to help in the wetting process and that this coating is hygroscopic (it absorbs water). According to him, if the cloth is old, there is a good chance that white areas will result when the stuff is epoxied, presumably because the coating has absorbed moisture and is not doing whatever it is supposed to do. For what it's worth.
Guy

[Thorne]

My understanding is sorta like GRussell's -- the glass or tape can get contaminated by being handled or improperly stored and shouldn't be used. So a lot depends on what you'll be doing with it...

[boattruck]

Blue dog, I have stored some tape 'poorly' as well, and experianced some goofy stuff in experimental use of same, unless it is many yards of stock, I would spring for new stock, and be sure of a smooth, successful job. Store any remainders where they will stay warm, dry and clean, Cheers, BT

[ccx2]

A rep from System 3 (I think) told me that 'glass cloth is coated with something to help in the wetting process and that this coating is hygroscopic (it absorbs water). According to him, if the cloth is old, there is a good chance that white areas will result when the stuff is epoxied, presumably because the coating has absorbed moisture and is not doing whatever it is supposed to do. For what it's worth.
Guy
I had/used some that was stored in a dry playmate cooler that wouldnt wet out clear no matter how i tried , some parts would remain white but i could tell it wasnt air under it. Now i know why.

[jonboy]

If denatured is cheap enough, and remember it's about 5-10% water anyway, wash it welll but skip the water and detergent...if it's potentially wet due to the hygroscopic coating then dry it...I'm guessing you live somewhere warm and sunny, but a RH factor above 70% should be good and you can dry it in the sun,the wind, a tumble dryer if you put in a muslin bag....

[ssor]

If denatured is cheap enough, and remember it's about 5-10% water anyway, wash it welll but skip the water and detergent...if it's potentially wet due to the hygroscopic coating then dry it...I'm guessing you live somewhere warm and sunny, but a RH factor above 70% should be good and you can dry it in the sun,the wind, a tumble dryer if you put in a muslin bag....

Denatured alcohol should be completely dry where water is involved or shellac will not dry properly. The old test was to wet a small quantity of black gun powder with the alcohol and light it. If the alcohol was dry when it burned off the gun powder would burn but if any water was present you ended up with wet gunpowder.

[ssor]

I have some 15 year old woven roving in an exposed roll in my shop. I will pull some off today and see how it wets out with polyester resin.

[Todd Bradshaw]

I believe that the Volan sizing (which is the treatment that makes it absorb resin properly and is generally the most common one used) is not only hygroscopic, but water soluable. Wash it with something containing water and you're likely to wash it off. Considering the current cost of resin, plus the labor and general fun value involved in trying to remove cured, bad tape jobs, using suspect tape just isn't worth the risk.

[ssor]

I found some 2 ounce mat and some 24 ounce woven roving left over form when I rebuilt my boat in '95-96 I wet it with evercoat polyester resin on a piece of pine. I went m-wr-m-wr and wet each layer in turn and rolled the air out. The pieces are about 6x6 and I would say that the wet out was normal. no white patches a few very fine lines but I consider that normal with heavy roving.

[ssor]

The resin hardened and I cut the sample into 2 inch wide pieces. The wetout appears complete. Splitting the glass off the pine pulls some wood.
I would not be concerned about using this on a new project.