My old flow mesh was running low so I bought a 100m roll of airtec greenflow media.have tried 3 infusions since and I am getting dry areas below the gel coat which are visable if you look hard enough.never had this problem before with my old flow fabric (bit heavier knitted construction).Has anybody else had any problems with greenflow?.its the only thing I have changed so it has to be it.is the red airtec flow fabric any better as I could probably change the roll for it as I have only used about 1/2 meter off this roll.
yes, I do not like the green, it flows too fast and leaves the laminate resin content too lean, about 30%, which leads to poor cosmetics. I like the red, it flows well and has very nice cosmetics, resin content of the laminate generally about 40% depending on your stack.
hmmm this is interesting to me, kinda got my mind working now uhh ohh lol
So would that mean that the green would be better suited to a more viscous resin (ie. Epoxy, or thicker VER)
Or would you just use the green on a larger mold?
And speaking of cosmetics. Could you elaborate on that. Are you refering to print through?
I don’t get print thru with the green flow medium, just some ugly azz parts cosmetic, air pockets etc, trapped air bubbles.
I’m gonna have to switch to the red myself. Thank God this green I have is nearly all used up. I think what happens is the green flows fast so the resin is flowing faster than the vacuum can pull the air bubbles out, thus leaving some trapped air on the laminate surface. This is just a theory I have. I could be wrong.
Anyone using Enkafusion flow medium?
The problem is not print through,just dry spots in the laminate which are visable.Was talking to another guy today who also had same problem with greenflow.The resin does flow very fast through this mesh,much faster than my old one so maybe it isnt giving the air time to escape.maybe it is designed for larger parts, boat hulls, windmill blades etc where a fast infusion would be needed and a few tiny dry spots below a coloured gel wouldnt show up anyway.its just not suitable for us people when we need a perfect finish on the cosmetic side of the part.My resin viscosity is 180cps with a 30 minute gel time.I dont know if results would be any different with a higher viscosity resin but dont intend to find out as im happy with my resin anyway.will talk to Tygavac (uk airtec suppliers) on friday and see what they think.Thanks for all your replies and advice guys.
Hers a pic of greenflow on the left with my old flow mesh on the right.
The one on the left is the Airtech Green Flow medium for those wondering.
I use 600cps epoxy and also another epoxy that is 350cps. The flow rate seems ok but i do not have enough experience to know if the part is infusing too quickly, too slow, or just right. It does just seem people here like the Airtech Red Flow medium.
I would like to try the Enkafusion and the Red to see how they compare.
We have the airtech, but I don’t like it only because it breaks when trying to pull it off some parts. The knitted black mesh we have doesn’t. Also, the “flow” is at an angle.
But at least it doesn’t curl up like crazy when trying to bag it!
Did a test today with my old knitted mesh against the greenflow.The greenflow flows the resin much faster than the knitted mesh but you cant see much air leaving the stack,the air can plainly be seen moving out with the knitted mesh.Results were the same,millions of tiny trapped air bubbles below the gelcoat with the greenflow and a perfect finish with the knitted mesh.Am waiting on a sample of the red flow mesh from airtec.Hopefully it will be better.
I seem to get a lot of tiny air bubbles in my laminate and even on the cosmetic surface in some areas. I was thinking of trying Enkafusion or the Red.
your old flow media it`s Greenflow 185
if you run low on mesh try a drainage contractor shop. mesh is the same. enka make drainage mesh.
Has anybody had good results with greenflow mesh for cosmetic carbon parts ?
Yes, it works just fine. People that are having problems with it just need to have a better understanding of the infusion process. It might look like it flows fast, but that’s very different than actually saturating down into the ply stack, which is why they get voids.
I solved the problems I had with occasional dry spots recently by slowing the resin down and altering where I finished the flow mesh after the part had infused.100% perfect ever since.will have to give the greenflow another go.Suppose different types of meshes flow differently and are designed to do different things .A technical advisor from umeco aerovac told me it has a lot to do with the contact area between the mesh and lay up.
Yup the problems are not from the flow media, but from the people using it!
Apparently there is a fast and slow direction in the mesh. This is because the ‘diamonds’ in the mesh are longer in one direction. I’ve tried it in different orientations and it doesn’t seem that noticeable. Doubling it up makes it real fast.
My problem is getting it to stay put on complex shapes. My latest solution is using little bits of tic tac to stick it down.
I’d like to revive this thread as I’m having some serious issues with my infusion process, cosmetics wise. After speaking to numerous professionals and switching processes a couple of times, I’m still experiencing pinholes on my surface which are really only resolvable once the part has been sprayed with a clear - I can’t see them after demolding. I’m at the point where changing my flow media from my current greenflow 75 to something else is really the only other thing I can think of, aside from buying a digital vac gauge to insure that I have less than 10mbar of pressure inside of my bag (something that I don’t want to do because I would rather not spend that type of money ATM [I’m using a twin stage rotary vane pump in a leak free system so I’m guessing I’m close enough to having enough vacuum draw])
Quick rundown of my laminate stack:
12k carbon
airtech econolease
airtech rb125 release film in P1 style
airtech greenflow 75
MTI hose is used
full resin degas for 20 minutes
Proset INF114 and 211 med hardener
frekote 770nc as release
All the other steps are pretty standard for an infusion, but I really just can’t trace where these pinholes are coming from. Rarely, a void will crop up, but for the most part they’re just pinholes.
Do you guys think the greenflow mesh could be the culprit? Will switching over to red flow or a knit mesh help my cosmetics?
Thanks
Regulating flow rate of resin by via pinching of resin feed line should solve your problems. Purchase some “squeegees” from the german:slight_smile: 
Actually you answered your question yourself. Guessing is not enough to produce void free laminates. Think about the money you have spent in labor and material so far? You can save that in the future by using a digital absolute pressure gauge so that you know exactly what is going on in your vacuum setup. As long you do not know the pressure inside the bag you will losing even more money by this kind of trial and error approach. Regarding the flow mesh Id recommend greenflow 185. Its a knitted material which is quite easy to drape.