hi all, i'm having issues with the final part not wetting out enough consistently. I am using the same mould, same layers, same resin and temperature conditions. absolutely no leaks in the bag and obviously the same vac pump. it visually appears to infuse at the same rate every time but only 1/3rd of the time it's actually fully wetting out the weave. it seems to be luck of the draw for me? i'm using a low viscosity resin, pulling a vacuum for at least 40 mins before infusing. i've tried clamping off the vac line and resin line like the easy composites tutorial, i've also tried allowing the resin to almost empty the pottle and only clamping the resin line and allowing excess to reach the catchpot and letting it cure wit vaccuum pump going. also moving around the resin feed/vac lines. i honestly have no idea what the cause is. would appreciate any help here.

I noticed you're from NZ, We are from Australia, and funnily enough, we are having the EXACT same problems.

We did notice when setting it up the vacuum infusion during the day as opposed to later at night when it was colder, we did have a much better finish.

We also found that infusing at a constant and reasonably quick rate gave us the best results. Keep in mind this was for small items. We did try slowing it down however that caused a s*** load of air voids like in the edge of your product.

Will definitely try clamping off the vacuum line first and then the feed line as i think we've been doing it the opposite way.

Hi buddy, hello everybody,

Shelby Cobra at which you worked is awesome!

There are several reasons which may causing dry spots at the infusion process:
- too high vacuum (boiling of volatile components)
- improper type of resin for infusion (low molecular weight solvents)
- poorly sealed or injured bag
- cracked mould
- too fast resin flow
- containing moisture fibres (water vapour problems)
- not degassed resin

Looking at the pictures you pasted, I'm pretty sure that your problem is, however, either leakage or cracked mould. If the bag and mould don’t hold vacuum, you will not infuse quality products no matter how hard you try.

After removing the item from the mold, do you have lots of tiny, quite annoying to remove, dots of resin remaing on the surface of mould? If so, this is the trace after that resin in the dry spots had once been. (and evidence of leakage, not a lack of impregnation at resin flow). Another confirmation of my theory is the fact that while you use the same factors and technology, you can make a good item from time to time.

While it may seem that the fibers after compression does not spring back, it does, just like a quilt. And that's why, even with minimal loss of mould containment, the vacuum pressure of "standing up" fibers cause
resin replacing with the air taken in fibers heterogeneity - see your photo.

However, I would definitely recommend 5 min. degassing prior to infusion. To cut a long story short, I'd suggest about 20 mBar (absolute pressure) for degassing and about 50 mBar for infusion.

To better diagnose your problem there is a need for more data - what exactly is vacuum level in your pump? (you definitely shouldn't use a two-stage oil pump directly to the infusion), what type of sealing type and bag you are using, how looks your mould.

Before you read the below, understand this is not supposed to offend (therefore please do not) but this is from MY experience with infusion:

thanks for some very good points. i have not been slowing down the resin at all. i will definiatley try this next time.

From my albeit limited experience you shouldn't need to infuse in an oven with that ambient temp.  I assume your using infusion epoxy.  I've had results like that and I found mine was solved by allowing resin to flow for a wee while after the vac line had been closed.  If you calculate your resin requirements before infusion so you have the right amount then infuse, close off the vacuum and let the last bit of resin flow in you'll find that these small holes fill with the last bit of resin.  Your parts aren't scrap, have a read round filling pin holes and that should recover them

so i should also clamp off the vac line first before the resin feed? i may just try that. i have a run of parts to make this week so some experimenting could be in order...

We tried clamping off the vac line first then waited a bit before the feed line, and indeed it did result in a much better finish!

We also gently warmed up the mould with a heat gun, and infused at a fairly fast rate without trying to slow it down by opening up the line clamp a little but instead had it fully opened. There were no pin-holes or wet out inconsistency in the final product which was a good feeling for once haha.

i wonder if it has to do with the part and bag relaxing and equalising out somewhat that just allows it to wet out better?