just wondering how long i should be leaving my jobs under vac?
using FGH clear at around 80 degrees F…
i have been waiting 6 to 8 hours but am wondering if it would be safe to pop the seal sooner.
thanks in advance.
jjp
I think CMP goes 12 hours minimum maybe more…
Depends in the epoxy cure time you’re using medium or slow…
Nice job on the rails…
what is that 1/2" or 1/4" bands?
How’d you get to bend around the nose…
Nice work space too…
Better than trying to do this stuff on the street next to the garbage bins…
or on a sloping drive way…
FGH short pot life at temps you mention go 6-8 hours, long pot life 10-12 hours. I used to only do the wood lams with long pot life and keep it 18 hours under vacuum. I started backing off the time under vacuum over the years to the above mentioned times. I usually use short pot life on the bottom and long pot life on the top. The top can take a few more minutes to get under vacuum versus the bottom. Since your board is not a long board, you could probably do both with the short pot life.
I bet you could go even shorter time spans, but haven’t had the need to try it. I only use the short pot life for the final fiberglassing of the board.
thanks for the feedback… i am using the short pot life and i went about 6.5 hrs on this one… i have had a number of failed attempts at the rails but i think i got it licked this one came out really nice and if i didn’t keep trying the stupid “s curve” tail it would have come out how i envisioned it should… i know there has been some talk about balsa rails the last few weeks so i figure in a few boards i’ll show my hard won method… that is one thing that is so fun about all this stuff is every time i do a step the next time it comes out better… oneula, i started with three 1/4" strips, but i have a wide belt sander 
so they shrank a bit… again i’ll show you when i can get it all on photos or of course you can come by and hang out…
we use to do as short as 2 hours bag time , using the bag and bake method , the only reason we did it that way was pure economics , limited pump outlets , so we needed quicker turn arounds to get the numbers …
these days i will do 12 to 24 hours depending on what system im using …
im real curious to see how long before i start seeing evolution , coz already i can see some interesting ideas getting thrown in the ring …
regards
BERT
I read on the Bag Lady website that she puts a drop of resin on the bench next to her vac table. When its cured, she takes the project out of the bag. Using a drop - or your pour bucket for that matter - lets you know when to stop, no matter the daily differences in resin, temperature, humidity, etc.
Makes sense to me, so I just poured a bit of resin on a scrap of glass cloth sitting on a piece of scrap balsa. When that was hard, I turned the pump off. It was about 10 hours, but I wasn’t checking it the whole time, so earlier might have been fine.
If you put the drop from the mixing bowl prior to the application of the to your project it would be accurate. If you put the drop from your bucket at the end of application, your test drop will cure prior to to the project in the bag.
I’m really looking forward to seeing your technique for the rails. I am 2/3rds of the way through my first set of rails. They are turning out fine, but I’m sure there is a much better technique.