I just pulled the cured tank cover out of the mold and to my surprise the surface look pretty crappy!
I have been having recurring problems with bubbles and voids in my laminates, and despite my best efforts I can’t seem to pin point the problem.
The first part is a cover I made a while back. This part came out just perfect, nice surface and everything no bubbles. On this part I didn’t even degass my resin. Just let it sit for a while…
This is the tank cover that I popped out of the mold today, it has some areas where the surface is nice and others where it sucks. I don’t know why even within a single infusion?!
more pics …
The mold for the cover was sanded to 1200 to remove any imperfections, and then waxed several layers, which were allowed ot dry over night between applications, then a lice thin layer of pva was sprayed on with no orange peel happening, very smooth.
I am using Ad-tech 820 epoxy infusion resin, where the total viscosity is around 350 mixed, I apply a bit of heat to the mold to get temps up and the viscosity a bit lower too. The resin was degassed under about 25inch Hg for about 5-10 minutes. then allowed ot infuse. There were no leaks of any sort the parts sat under vacuum with the pump turned off for a long while , while I mixed the resin/hardener and degassed/ got ready etc…
I can’t for the life of me get a decent consistent infusions.
I find that bubbles remain trapped under the peel ple and even within the flow media and don’t move away… The best finish I seem to get is if I place a minimal amount of peel ply and flow media over a flange part that will not actually be part of the trimmed piece and let the infusion take place just through the reinforcements. But this takes a LONG time and if the stuff kicks before it’s infused all the way, I’m hooped…
even over the areas covered in peelply and flow media the infusion takes place quite slowly, I only had a single layer of 5.7oz twill and then one layer of 12oz twill.
Also, when I do get areas or parts where the surface is pitted with bubbles or voids, the corresponding back side with the bag over it never looks like this, it looks perfect!?
any help would be great!
just for starters… i wouldnt keep using carbon. I KNOW its hard to resist. but perfect it first with regu. fiberglass twill same weight. it will help you A LOT. also, are u using any gelcoat? it not, ive had these issues… when i switched over to gelcoat there was no problem. another thing, dont put flow media on the part… put it right over peel ply. you wont be able to take it off later if u leave some on the part.
those air bubbles are maybe coming from the heat source… not 100% sure thou. are u using a venturi system or a pump? your resin is hardening to quick and is not allowing the air out of the resin when infusing (even if u degassed)
another thing, when heating up epoxy your resin time is lower and lower with more heat.
I know I shouldn’t use carbon , but when I got a couple good parts then I replicate the entire process the same way only to get different resuslts…
No, I’m not using gel coat
the resin flow media was over the peel ply, I just haven’t peeled it off yet…
I’m using a vac pump, the resin I use has a 45min gel time.
where abouts in relation to the vac source are the bubbles appearing or are they just random? I used to have problems on infusions similar to this, I would infuse a part just short of the vac line then clamp everything off. Come back in the morning with no leaks and near the vac line there would be voids and resin dry pits much like yours.
What was happening is I was stopping the resin flow just short of the peel ply resin break and clamping off the vac line way away down the line. Its almost like the pressure was equalizing then and because there was no resin at all in the vac line in the bag and it started creeping back into the part.
Thus he says leaving a crappy area always on vacuum side a couple of inches in on the part. Now I carry on infusing till it sucks the resin just in the vac line in the bag (not anywhere near the pump) and clamp off as close to the job as poss and perfect parts every time. 
I get the bubbles in different places, I clamp right close to the mold on the resin line, I think my problem is a bit different then that, but I will give that a try next time thanks.
different weaves and weight materials will give different surface finish when in fusing. I tried infusing twill with a 20oz cloth, i tried some many different ways, but when it came down too it, it just wasnt a good choice of reinforcemnent, perhaps you should try a different back reinforcment? are you using green or red infusion mesh? I find that the green with epoxy doesnt work good. what type of bag material are you using? be sure to use very tough bag, typical nylon bags are riddled with tiny holes witch cause poor surface finish
I’m using a very thick bag film (4-6mil I think), not sure what sort of material it’s made from but the surface in contact with the bag is alwways A+ regardless if there is bubbles/voids on the finish side. it’s red mesh I’m using.
the 12oz twill is 6k carbon or a glass? have you tried a different combo before? you really should do some test panels, get a piece of glass and test a couple different combos of material and methods
Any time I do a test it turns out good and then I come to do a part and it turns out not so good:confused:
the 12oz is carbon
it very well may be the bag you are using, get vacbag2000, works great. does your piece infuse equally? are you letting resin enter your outlet hose? make sure your resin trap is below your part, I have found that resin that does happen to enter the outlet will not go up hill in to the resin trap, which would cause a bag pressure lost, possibly causing air to enter in the part. if you have the catch pot below the mold, the resin will pour in to it without a problem kepping a solid bag pressure
I clamp off the vac hose right before it gets any sucked into the hose.
you clamp the vac hose, or the resin hose? you need to leave the vacuum line open until it cures. are you using a resin trap?
20_RC51 the one photo of your tank cover you pulled out of the mold today, the cloth looks dry, like not enough resin reached that area… from my point of view it doesn’t look so much like bubbles as it does like dry carbon.
yep, your laminate is dry because the vacuum was not pulling enough resin thru the lay up. If you can let your vacuum run longer without clamping off the vacuum line at all. On your resin catch pot/vacuum pot… put a gas ball valve between the vacuum pump and the pot. After a couple hours you should be able to close that valve, then shut your vacuum pump off. If you don’t have any vacuum leaks then it should hold vacuum. just my opinion.
well, if he is cutting vacuum off just after infusing, this is definetly the problem
I will let it pull vac longer, I hope this is my problem… what I’d do is clamp the resin line right before i get any resin into it and then let the vac pull for a while until it looked like the resin wasn’t moving any longer (meanwhile i had a heat lamo on it the whole time).
fast rr, that area does look like there wasnt’ enough resin there but then there is an area around it that is just fine… its wierd.
maybe I should hold off on applying heat to it and see how well it infuses at ambient temp. cause it might be gelling a bit too quickly?
what sort of geltimes do you guys have onthe resins you infuse with?
in any vacuum process you need to leave vacuum on till the resin has hardened. otherwise it defeats the purpose and air enters your laminate
Dont have any experience at all of vacuum process, so wonder if you are saying that pump needs to be running continously?
If pump is running continously, and resin flow is clamped, wouldnt even the slightest vac leak mean that air is going to get sucked in, and cause all sorts of problems?