greetings everybody,
can someone point out what must have gone wrong to cause this “dry” spots on the finish. I was making a test sample for infusion with lantor soric core followed by a layer of glass fabric and 1 layer of carbon fiber on each side. using adtech low viscosity resin 650 cps. I attached pictures of the final surface as well as the setup right after i clamped the resin inlet. no leak and under 27.5" for 24 hours. mold was waxed and buffed twice with partall paste wax #2 and 2 applications of pva (brushed). I appreciate if you guys would point out anything you see that i might have done wrong.
thank you
That’s PVA for ya, throw that crap away. Just wax and buff your glass and you’ll get the gloss finish you want. You could also switch to a semi-perm release and save your arm from buffing so much but the wax only method will keep you from spending more money and give you the results you desire.
that is good news because I hate applying pva … I will only apply wax next time and will share the results. thank you. does everything else in the setup seem ok? this is my 5th infusion so any criticism is appreciated.
It’s hard to tell where the flow media ends. Do you have a resin brake? That might also have something to do with the finish but I’m sure it’s the PVA. Other then that it just comes down to personal preference on setting up the infusion. One example is you are double sealing the bag, that is only really done on some high end applications and only taping once will be fine which saves you more money, I only tape once and don’t get leaks or have problems. Then the placement of hoses and use of t’s or no t’s is all just personal preference that comes with experience.
One thing I always want to say to people on here is Experiment Experiment Experiment the best way to learn is to do it yourself. I’m glad you are doing that and posting the results. 
But the knowledge that comes with experience is way more valuable then what you can read. In the words of Werksburg “Finish what you started and you WILL be successful.”
Although PVA will make the surface matte, it very likely is NOT the cause for the entrapped air.
27.5" of vacuum (-0,93 bar) is in general not low enough. Try and get lower if you can. Also, the Soric needs about 30 minutes to “stabilise”. There is a lot of air entrapped in the extendospheres, which basicly is what Soric is made off. The resin might have travelled too fast for the carbon to infuse properly. Try and setup a slower resin feed.
Getting to -0,98 bar at least during infusion, and throttle back to -0,92 after infusion might help you get rid of the air pockets.
With a leak free bag you don’t have to reach a lower vacuum. I’ve gone with a vaccum as high as 23" with soric before. The surface finish Bryan is experiencing is the same surface finish I have experienced with brushed on PVA when I first started into the world of composites. Now I’m not saying PVA will always give that finish DDCompound does a great job at showing you can get a great finish with the PVA.
I do think you have a point with the resin flow front traveling to fast and that’s why I mentioned the resin brake. But being late at night I kind of forgot the soric is the flow media. :o Maybe a smaller intake hose or flow regulator could solve the flow issue?
did you degas the resin?
I don’t think that the PVA is the problem. It seems that you have not degased the resin or your vacuum is not tight! I posted a video in the products talk “MTI hose”, maybe it will help you?
In most times you don’t need a flow media when you work with Soric.
Those sample panels I made in your MTI hose thread didn’t have the resin degassed. You don’t have to degas to get a perfect finish.
Yes, but you worked with the MTI hose, if you work with normal spiral tube these problems may be caused. I think the vacuum was not stable or he infused not enough resin.
Your right these problems might happen with normal spiral but that’s only if care is not taken when mixing the resin. I use spiral on all my infusions and never have this problem. The only times I did experience this problem was when PVA was used. When I did a identical setup with wax only and another with semi perm the problem went away and has never came back.
Bryan also mentioned he had no leaks so I would think he would know if this was caused from air leaking threw the bag. Also the streaks in pic two remind me of the brush strokes it takes to put the pva on.
Don’t apply PVA with a brush, but spray it (add a dye so you can see) or apply with a sponge.
thank you everybody for your input
1-“Do you have a resin brake?” yes, i wrapped a spiral tube with peelply and laid 3 layers of peel ply between the spiral tube and top end of the layup. ( i hope that is the right way of making resin brake:)
2-“you are double sealing the bag…” in the picture it definitely looks that way, but the outer yellow tape is just some masking tape i put all over the edges of the glass.
3-“I’m glad you are doing that and posting the results. :)” thank you, and sharing this info is the least i can do for all the help i have gotten from this forum.
4-“27.5” of vacuum (-0,93 bar) is in general not low enough." unfortunately that is as low as i can get with mu pump.
5-“Also, the Soric needs about 30 minutes to “stabilise”…” i did not know that and i will do that on my next test sample.
6-"did you degas the resin?“no, however i am going to test that as well.
7-“In most times you don’t need a flow media when you work with Soric.” ok, so the whole purpose of my test sample was to see the difference in use of an additional flow media (green mesh) while infusing with lantor soric. i had done double sided finish by using caul plate and lantor soric and a layer of carbon on each side, however i noticed that the resin was moving very slowly, and therefore i decided to put flow media (green mesh) on the lower part of this lay up and did not use any green mesh on the upper part. (you can see it better in this picture)
resin flow was as expected on green mesh but again very slow once it hit lantor only.
so i came up with another test which i will attempt in couple days. please let me know what you think.
i am going to have 5 different square samples (each side about 6-7” )under the bag at the same time so they are under the same pressure. each sample would be lantor and 1 cf 3k on each side. and i will leave it under vacuum for at least 30 min before infusinon. 1st sample would be the exact one as i did for the previous test( waxed, pva, and green mesh) 2nd sample: same layup no pva. 3rd sample: i will lower the resin intake by half through a valve. 4th sample:with green mesh and pva but degassed resin and remove valve. and 5th sample would be no pva and no green mesh and again with no valve to lower the resin flow and degassed resin. (i might do the 5th sample separately using some MTI hose which Canyon gave me not too long ago when i met him to learn more about infusion. I hope i have enough of that.
any suggestions?
edit: after more research i think i will get rid of the additional flow media (i might leave it for one sample just for comparison)
Is a resin brake,used in all infusion,I understand that the reason is to slow the resin down once it has passed the mesh,could any one explain the possible pro and con’s.many thanks.
I usually get really nice gloss finishes when spraying PVA. Never applied it with a brush though.
not all infusions, but it never hurts. It allows the resin in the part to flow through and fill completely (barring any racetracking), but still allow an area that can slow the resin down and make sure any trapped air to escape and fill with resin. If you have racetracking, it can provide a buffer zone before your vent line as well, which can draw the voids out sometimes.
Only con i can think of, is needing a larger area for bagging. Tables don’t matter sometimes, but a complex mold might not have room. Then you just deal with what you got, and bag it well
ok, so I could not wait till i get my MTI hose (ddcompound generously sending me a test sample) to continue my experiment. so I made another sample and divided the sample in 3 sections as seen in the picture below. top part only waxed and buffed (partall) middle part wax and pva applied using brush and lower section wax and pva applied by foam brush.
I video recorded the whole infusion which i will be posting once i finish editing. meanwhile as you can see in the picture (more visible in person) that upper section with no PVA definitely has a shinier finish. no difference between regular or foam brush pva finish, however, it was much easier to apply pva with foam brush.
in addition, the bad surface finish of my last sample was not caused by PVA alone. I believe that i did not use enough resin and starved the laminate. more on that once i post the video.
Thank you again for all your help.
The PVA is not the problem, usually applied with a smooth cloth, no bruch, no spray. Now the problem with air is usually the resin runs too fast from the one side to the other. You have to control the resin and make it runs slowly. This gives the opportunately to wet all the layers of carbon and take out the air. Sometimes when I am forget to control it, I have this problem 
Try it