Fiberglass Mat Weight

I see plenty of threads about "How many layers should I use?" and generically it 5-7 and >= 3/8"s thickness, but no one ever mentions the weight of the mat or cloth. I have been using .75 and 1.5 ounce mat but to get to ~.25" it has taken about 6 layers, maybe more. So I have to ask what weight mat/cloth is being recommended for 5-7 layers and a thickness > 3/8's?

After doing a bit more refined a search, I found one post that recommended 8oz.

In boat building we use multiple layers which are offset arround 35 degrees from the previous layer. This provides additional strength. I don't think, however, that in this instance you would see any real benifit.

Stormshadow

most people use 1.5 oz because it is the easyiest to find.......the thickest i would use is 3 oz. even that can be hard to bend in certain contours and corners. the thicker the mat the more difficult to soak it all the way thru.



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Audiomechanic, how many layers of 1.5 would then be needed for reasonable thickness. I've been using 1.5 and roughly 6 layers amounts to about a 1/4" which seems to be contrary to what many here say. So then are we talking ~12 layers rather than 6-7 for a reasonable non-flexing enclosure. Correct or incorrect?

i usually use about 6 layers of 1.5 then i use duraglass to fill in all the holes and smooth it out. makes the inside of a tirewell nice and smooth, plus it makes the thickness the same thoughout the enclosure.

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So defective 6 layers of 1.5oz + lets say about a centimeter of duramix is sufficient for a solid fg enclosure. I continue to ask because my first attempt has been reasonably successful but thickness is questionable and I'd hate to have to start again due to the glass being to thin.