still getting some small tiny TINY bubbles. i KNOW its not the bagging. its perfect, no leaks. i THINK its the resin… i might just vac the res of air first and do that quickly.
or, it might be in the gel coat layer…
another question… i clean my gun with acetone, is there something better i can clean the gelcoat off!?
it might be your resin viscosity is too low and your sucking too much resin out of the laminate. what resin system are you using? viscosity? you could try a thicker resin, or you could try regulating your vacuum pressure to a lower pressure by opening a a seperate valve
Do you keep the vac pump running through the whole cure process?
its a venturi with a mac vavle… so… its not “running” per say… but if the vac pres. goes down it will turn on
How much does the vaccum have to go down before it turns on? Sounds to me like the plies are being compacted, but when the pump shuts off and air starts coming in it releases pressure on the laminate.
nope. trust me. its SUPER tight. im getting 26" of merc. and it never goes off to refill. what i sometimes do is make the switch run for 1 more cycle till it reach 28". i really think its the resin.
Just a thought… does your resin cup have air bubbles in it? Maybe you could degas the resin prior to infusing like you mentioned.
Even if the resin is full of bubbles, they should get pulled out by the infusion process. The laminate itself is full of air afterall before infusing, and those bubbles don’t stay.
What is your mold made of? It might be porous, maybe just in one area. Seen it happen, where bubbles just kept appearing after the resin feed line was clamped off.
surface is super shiney… i def. think its the gel coat layer. ill give it a shot and see what happens on the next infusion with the resin vac’ed also.
are you using epoxy or vinyl? IF you are using epoxy and the viscosity is too low, there is a good chance that you are pulling too much resin out. also could be the flow medium.
Could it possibly be the same problem Grat the Greek was having?
http://www.compositeforum.werksberg.com/showthread.php?t=1544
1: i doubt it. Styrene might clean it, but it’ll also clean everything it touches…like the skin off your bones. Nasty assed stuff. Acetone is the strong and SAFE solvent of the bunch.
2: When you are letting resin in, are you keeping the vacuum sucking? Because you can compact it down to 28, but what happens when you let the resin IN…the pressure goes up. That little amount might still let some trapped bubbles expand.
So, if you aren’t…keep the vacuum running the entire time until the resin gels.
Degassing the resin is always a good way to go as well. That is a standard practice. As with many threads, use a large bell jar, or metal case that can hold a strong vacuum. Let it in there for a few min, then let in the air.
what always seems to happen to me is that bubbles get trapped under the peel ply and even within the resin flow media and they don’t even move! Some do but others don’t and I end up with voids and bubbles…
I’m using a ~350cp viscosity epoxy that is heated and the mold is also heated to further reduce the viscosity… still this happens.
you are probally infusing too much resin in to your part, you dont want resin to get in to your outlet tube, this will cause air to slowly enter in to your part. also you should always use a high quality bag film. and you really shouldnt need to heat your mold or your resin up, I infuse parts with 400cp infusion epoxy with out heating with no problems.
When you say standard practice, you mean for infusing, or does that include vac bagging as well?
it would be standard for infusing, not neccesary for vacuum bagging since you us a breather whitch will pull the air out
Actually those bubbles are present right from the start, with a bag that holds vacuum. I’m using red resin flow media, and the resin still seems to travel very slowly regardless. Do you have any idea what sort of rate your parts infuse at with your said resin and flow media, for example (X number of inches per minute) with how many later/weight of fabric/over area with flow media/without flow media/inches of mercury?
I’m using a transparent gold bag that doesn’t have much stretch to it, but I put enough pleats to ensure nice coverage of the part. I let the vacuum pull for a long time before I actually allow the resin to get sucked up…
you need to degass your resin for a few minutes. make a degassing jar from a glass jar with a metal top, its easy and cheap. nylon bag does not work well for infusion, it is not uncommon do have tiny holes in this bag. vacbag 2000 works awesome and has some stretch to it. the part I infuse is 1mm thick, 60" wide, and I infuse the width of it witch is 25", takes about 10 minutes with a epoxy that has a viscosity of 400cps. also make sure you have the infusion mesh orientated in the correct direction, it flows better in the length of the roll