Style 7628 Glass Cloth $1/yard

TRF,

Have been working with glass cloth and resin over the holiday weekend. Some of that has been with style 7628 cloth. It’s cost is about $1 / yard as it is perhaps the most widely produced cloth. It is the foundation of FR4 circuit boards and of G10 laminates. It is a tight woven cloth designed for high ratios of fiber to matrix. And that is the problem.

This stuff is sometime difficult to saturate. It is prone to air bubbles that must be eternally chased by squeegee and roller. Combined with 30 minute resin systems the situation becomes quite tense.

Anyone have some tips working specifically with style 7628 or should I just give it up for a more “open” weave? I would like to use the stuff in open lay-up not vacuum bagging.

Feckless

Is your 7628 untreated? Typically if you buy very cheap it will not be. Read the first couple of paragraphs in first section on this page: https://www.epoxy5050.com/fiberglasscovering.php3. Untreated fabric will be hard to wet out.

dixontj93060,

Good call but the datasheet says Silane finish. No date code but probably less than 3 years aged. I think the issue is technique when working with such a dense cloth.

Feckless

1. Fingertips >> rollers or squeegies, in my experience. Wear two pairs of gloves, and don't hold your hands fingertips-up for very long, or else it might drip down your arms.

2. Slower curing epoxy system?

CarVac said:

2. Slower curing epoxy system?

Click to expand...

Yeah, that's were I'd go next. Nice and slow and a lot of hand work. Kind of like a massage--G-rated of course.

TRF,

So I think I have this figured out. Didn’t have enough epoxy on the phenolic tube prior to laying the glass. This time I lathered the whole tube up to the edge of dripping. Most of the epoxy was then worked up from the bottom with a squeegee. Perfect!

My previous experience with that cloth was on a mandrel covered with impermeable Mylar. Worked great there, I’m guessing, because none of the resin was lost to the substrate.

Feckless again