Resin Starvation?

The appearance of the panels I've been wet laying and and vacuum bagging has me a bit concerened. I'm using epoxy and 24oz triaxial 45,45,90 on 3/4" 5lb pvc foam. I believe the 90 layer is double the weight of the 45 layers and appears lighter in color after cure. I've seen this in nearly all my vacuum layups with this fabric including those in a mold and those with and without breather/bleeder. The only layup that it hasn't been apparent is one single layer without peel ply. My typical resin content is averaging around 37%, 63% fabric. I stopped using bleeder because my resin content was dropping below 35%. I've seen some commercialy availabe panels laid on PET core and the glass also has a lighter color. Is this glass apearance typical for vacuum layups?

 

Yes, the lighter appearance of the 90° layer in vacuum layups is typical and normal. It usually occurs because heavier fabrics appear lighter after curing, even when properly wetted, and does not indicate poor resin content or wet-out.

 

Have you ever used any other resins? I might be curious about viscosity having an effect and I see no mention of whether this is for infused panels or if you are bagging a hand layup to remove excess resin.The lowest resin content I have seen was 41%,but this was carbon prepreg for an autoclave cure.Even so,it didn't flow too well an the following batches were 44%.

 

Thanks, that's reassuring. It's also possible this fabric is designed for infusion and the 90° layer is bundled differently for transporting resin.

 

A couple follow ups..

1. If the glass is 90, why are the strands running the 0 direction? Am I wrong?

2. The channels in the 90 degree are clearly devoid of resin. What is your ratio under peelply with bleeder above it? For most use cases, the channels will need to be filled, so making them voids is questionable.

3. what is the use case and where does the?90 go? 45?

My general hunch is you’ll need to use peelply in the stack.