Talk Composites - The Forum for Advanced Composites

Is it worth to degass the mixed resin when working with the wet hand lay-up method?

http://www.talkcomposites.com/Topic37904.aspx

By cyclous - 9/15/2020 1:07:30 PM

Hello everybody,
I am new to composites and I have skinned my first parts with quite good (not awesome) results. I have of course first watched many YouTube tutorials and read this forum for many days. (Thank you all).
When mixing the XCR resin it retains many very very small air bubbles. Heating up the resin a little bit with a head gun does help of course, but there are still a lot of very very small air bubbles visible in the cup.
I assume that if I degass the mixed resin in the cup then it would be completely bubble free. But if I apply the resin with a brush, would then again air get trapped in the fibers (because of the brush) making the degassing process completely useless? In simple words, is it worth to degass the mixed resin when working with the wet hand lay-up method? Is there not even a small benefit?
I do not have the required equipment yet and that is why I am asking.

Thank you.
By ana - 9/20/2020 6:19:00 PM

 
Warren (Staff) - 9/15/2020 1:44:07 PM
Generally degassing is not needed for wet lay up.  You can leave the pot to stand for 5 minutes or so.  Then use it and waft a heat gun over gently if you have bubbles still there.  However, degassing can be done if you have the equipment, and although some air may get in when brushing, it may help a bit.

Also check your mixing method, generally a "folding" type action traps less air as opposed to other stirring methods.

Another factor is temperature.  if you are working much below 20C, the resin thickens which means it will trap more air during mixing.


hi my friend
I am producing a granite sink with a gel coat as the top layer and polyester resin and silica powder as the second layer. first, I apply a gel coat after 5 hrs I add the second layer. pls let me know what is the best time for demolding ? after gelation or after exotherm temperature or I should let the sink remain in the sink for 24 hrs post-cure and then de-mold the sink? when i want to de-mold the backside comes out very good condition but the top side of the mold: the male side: comes out with damage, unfortunately.
pls help me if you have experience with polyester resin
my mold is fiberglass with vinyl ester
I use wax for both parts
tanks so much
p.moeinian@gmail.com