Page 2 of 3

Re: Resin percentage vac bag

Posted: Tue Nov 14, 2017 2:46 pm
by narfi
Hehe.... you might be more accurate.

Back on topic though and to the point,

5.2 glass
2.6 resin

It doesn't matter if you call it 50% resin to glass, or 33% resin to total, it means the same thing.

Even more important though, it is a good ratio for vacuum bagging, and if you have consistent results with this ratio without voids then you are doing good and probably no need to change anything.

Re: Resin percentage vac bag

Posted: Tue Nov 14, 2017 8:28 pm
by fallguy1000
Thanks guys, I made another part today with different glass, 18 oz biaxial. Man does that s..t move and change. I stretched it out and put it on the roller and laid it out and it was like 1 1/2" short! I will just laminate some big arse tapes on it on the join, but another new experience.

33% resin to total is a good number then?

I put another piece of breather on today's part. I will have to subtract for the fabric short, but then I can give another number to see where things are at. I will post another picture of today's work on my build shortly.

Re: Resin percentage vac bag

Posted: Wed Nov 15, 2017 11:39 am
by Tungsten
If you use 10lbs of epoxy to wet out 10 lbs of glass thats,50/50 or 50% Vf
same but with 5 lbs of epoxy thats 25/75 . Infusing at max pressure at my elevation (3300') i can get 40 resin/60 glass.
Hand layup i'm around 55% resin.

Re: Resin percentage vac bag

Posted: Wed Nov 15, 2017 2:25 pm
by fallguy1000
Tungsten wrote:
Wed Nov 15, 2017 11:39 am
If you use 10lbs of epoxy to wet out 10 lbs of glass thats,50/50 or 50% Vf
same but with 5 lbs of epoxy thats 25/75 . Infusing at max pressure at my elevation (3300') i can get 40 resin/60 glass.
Hand layup i'm around 55% resin.
Something wrong with my numbers?

Re: Resin percentage vac bag

Posted: Wed Nov 15, 2017 3:23 pm
by fallguy1000
BH3

Total 11.2
Core 3.95
Glass 4.7
Back into resin 2.55

54% resin to fiber.
35/65

Should I back off the pressure?

Re: Resin percentage vac bag

Posted: Wed Nov 15, 2017 7:22 pm
by Jeff
Fallguy, I will get back to you around 10:00 AM your time regarding the tape!! Jeff

Re: Resin percentage vac bag

Posted: Thu Nov 16, 2017 5:22 am
by Tungsten
fallguy1000 wrote:
Wed Nov 15, 2017 3:23 pm
BH3

Total 11.2
Core 3.95
Glass 4.7
Back into resin 2.55

54% resin to fiber.
35/65

Should I back off the pressure?
No,as said already if it looks good then don't change it.
If you really want to know what your percentage is do a test on just a small piece of glass no core,weigh before and after.

Re: Resin percentage vac bag

Posted: Thu Nov 16, 2017 2:22 pm
by fallguy1000
Thank you Tungsten.

Re: Resin percentage vac bag

Posted: Fri Nov 17, 2017 12:59 am
by Evan_Gatehouse
33% by weight for epoxy resin/E-glass is actually a very low % of resin! That is more typical of resin infusions done very well.

I can do a good hand layup at 50/50 but it looks almost dry. 40% resin/60% fiber by weight is more typical of vac bagged layups. Yours might be a little low on resin (but if it all looks wet out... :D )

Re: Resin percentage vac bag

Posted: Sat Nov 18, 2017 10:02 pm
by fallguy1000
These panels look better than anything I have done. My waste is rather high, though. Lotsa epoxy going in the trash in the breather. The wetouts are tough with peelply on the table.

I am using mat backed tapes though and I calculated 10 oz extra weight per sq yd and about 225# add to boat for mat backed tapes. Does that sound right? I can live with it, but not going to tape the tops of my bunks n such unless they get a stress crack later, or might just buy some 12 oz tape for accessible watertights.

I think my vac pump and not opening a bleeder is key to things working.