First infusion has porosity


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Hanaldo
Hanaldo
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Degassing is totally unnecessary for a perfect cosmetic finish, I do it day in day out and never degass unless I'm doing a structural part. Degassing just complicates things unnecessarily. 
oekmont
oekmont
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In my opinion a really perfect finish could only be achieved with a properly degassed resin. During the infusion the resin in your part is under lower pressure, wich means the gas bubbles become bigger. Some of these bubbles than fuse, creating bigger bubbles, wich can be seen even after being brought back to normal pressure. Most of the bubbles leave the resin during the infusion, because of the lower viscosity of gas compared to resin. If you look closely, you might see very small bubbles running to the resin front during the infusion, while getting bigger. This extension is caused by the pressure difference. At the resin feed there ist allmost normal pressure, at the vacuum line there is allmost full vacuum. A properlyrics degassed resin does not degas at all during the infusion.
Warren (Staff)
Warren (Staff)
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With a long pot life what you can do is leave the resin to stand for 10 minutes before infusing as most the big bubbles will come out then.  Also when the resin gets to the vacuum feed, allow a bit more resin to flow into the catch pot.  Once you clamp off the vacuum feed, allow the resin feed to stay open another 10 seconds or so.  The extra resin often helps avoid pin holes.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
Roo2
Roo2
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Hmm. No I didn't degas. The resin I used was quite runny and I didn't stir it vigorously. I didn't see any bubbles but I guess there could have been some I didn't notice. I guess I could degas in my resin trap before infusing next time.
oekmont
oekmont
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Did you degas your resin? If not, that will very likely cause the problems.
Roo2
Roo2
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Hello there,
I've just completed my first infused part. It's a shell for a home made metal detector coil. I'm generally happy with the result but would like to improve the surface finish on future parts.
The part is made with 2 layers of 200gsm fibreglass and a low viscosity epoxy that uses a very slow hardener. It took over 4 hours to start to gel in a warm environment. I'm using a pump that can get down to about -28" and  after I infused the resin it was turned off. No evidence of leaks where seen and the vacuum gauge needle didn't move for the entire cure duration.
If you look at the attached photo of the shell on the scales there are a few areas that appear to have porosity. Small holes between the fibre weave. Could that be caused by using hardener that is too slow and all the resin has been squeezed, drawn out of the very thin laminate? Or is it just evidence of tiny air leaks I couldn't see or measure?
Thanks
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