I am having a recurring problem of air in the face of the carbon , (please zoom in on pic)
I am infusing on a sheet of glass as a test.
I have 30 IN Hg vac , no leaks, holds vac for duration of cure.
using 4 layers of carbon , peel ply , flow mesh then vac plastic sheet.
I am clamping the resin line just as the resin gets to the vac line , then clamping off vac line about a min later.
Also tried not clamping vac line and leaving the pump on . ( worse)
I am mixing EP 085 resin 100 g to HP 085 hardener 35g mixing for 1 min then de-gassing for 10 mins in the catch pot prior to infusing.
Try clamping the vacuum line first, then clamp the resin feed line about 15 seconds later.
picture of setup? Im assuming without seeing maybe you have no resin break, and/or not ending mesh before end of laminate. Setup is very important.
So your infusing the panel
Then spending a minute trying to suck the resin out off it !
As above said do your shutdown the other way round
I have a tub style part with the feed line in the center of the bottom and MTI hose running around the entire flange. I use the mesh all the way up and under the mti so it has room to get the air to vac. In this case I don’t think a resin break would work right, also don’t know if really needed using mti hose…
A resin brake zone always helps, even if using MTI hose. But there are many questions. Where and how did you measure the vacuum?
When you say no leaks how did you measure that.
Is the resin a infusion resin and did you degass?
I have a vacuum gauge on the catch pot i pulled down vac and left for 30 mins prior to infusing with no drop.
Yes it is infusion resin , I de-gassed for 10 mins in the catch pot , there were no visible bubbles in the resin in line during infusing.
I have just tried closing the vac just before the resin line as Hanaldo suggested … much better but still not perfect.
I need to research resin break , unless anyone has a quick description ?
I am taking the flow mesh and peel ply beyond the laminate.
Thanks for the advice all. Nick
I would try ending the mesh short by 25-50mm. This prevents the resin from overflowing and trapping air. Otherwise the resin flows right to the MTI hose and cuts off the vacuum before all the air has been removed from the laminate
Nick, I agree with these guys as far as adding a resin break and let the part fully wet before clamping. On a side note, I wanted to thank you for posting your hull build on x-h20 back in 2010. That inspired me to enter the world of composites and eventually create my own ski hull and parts as well.
Thats great to hear ! is there a thread for your build ? i still have a garden full of jet skis ! lol but am working on a motorised surfboard project at the moment.
Thank everyone for the input , I tried closing the vac line first and the resin line about 5 seconds after , the result is a lot better but still not perfect . There are still some air voids round the edges.
Yes i did de-gas in the catch pot for 10 mins, measuring the vac with a gauge on the catch pot , no i didn’t end the mesh before the laminate.
No I did not have a resin break , could someone explain what that is or point me to a thread covering it please.
A resin brake is exactly that, an area before your vacuum side with no flow mesh, only a material like peel ply or breather cloth. The idea is that the resin can’t flow quickly through these materials like it can through the mesh, and so it hits the brake zone and slows dramatically. This gives the rest of the laminate a chance to catch up to the flow front before you start sucking resin out; or in the case of using MTI hose it gives the laminate a chance to completely wet out before the resin reaches the MTI hose and seals it, stopping any trapped air from escaping.
You have to remember that the resin flow through the laminate is staggered. What you see from the top is slightly delayed on the laminate surface, depending on how thick your laminate is and what materials are in the stack. So the flow front you see on the top is slightly ahead of the resin flow underneath, and if your top flow front reaches your MTI hose before the ‘bottom’ flow front, then you will be trapping voids in there that are likely to be present on the surface.
A resin break is on the far left side of this part. It is just, in this case, about 50mm of peel ply between the part and the vacuum hose. This part is 600mm long and infused perfectly in about 25 minutes.
Thank you for the info I will try with a resin break.
yes, great explanations of the purpose. Thanks guys
Nickwad, here is a thread of my latest ski. It’s actually the 2nd generation as the 1st generation was just to learn from. Haha http://www.x-h2o.com/index.php?threads/the-hammer-with-a-touch-of-carbon.167702/
Awesome work mate … blown away !
Hi,is it the same thing if you don’t use MTI?
Is your catch pot a home made ??
Yes this is a general rule to use for infusing with or without MTI hose. However keep in mind its only general and you may need to make further adjustments. And if you use spiral, typical setup is to use peel ply to connect vacuum source to laminate, spaced 50-100mm. Though again there are variants to this rule.
Some great info here.