Vacuum bagging and lamination clarity

General Discussion
1

I’ve noticed that when I vacuum bag, the work is less clear than standard laminations. It turns white and hazy.

I did some 4 oz S cloth over carbon, and vacuumed it under peel ply.  When it was done, I couldn’t see the weave of the carbon, instead I got a milky grey.  It was almost like the pressure from bagging squeezed out too much epoxy, to where the cloth was getting dry.  Hot coating didn’t help.

When I do hand laminations, no bag, 4 oz S cloth over carbon, the weave shows perfect.

It seems like bagging is good if doing clear and white, but not so much for tints or paint underneath.

Any ideas?

2

I use 1 mil. blue or pink perforated ply,
2.0 oz breather and 6hg or less on 2# EPS.

3

S-glass is notorious for showing weave, low resin content makes it show more. S + carbon is a recipe for a stiffy, unless the board is long and/or thin.

Good on ya for bagging your lam, though. If you do it right, you can get way more fiber per unit of weight and improved physicals too.

4

Thanks for the reply, Mike. 

I wouldn’t do an entire carbon/ S cloth board.  You’re right, the sample I made was super stiff.  I’m just working through a few ideas I have.  A lot less costly to do a 6" sample than a whole board!  I’m just supprised how milky the vacuumed S cloth turned out.

I was wondering if it was something else I did, or do others have the same result.  A few more experiments are in order.

5

I have same problem with my first vacuum bag lam with Eglass. Too much pressure=lam too dry. Lakewakes give a good answer.

Sorry for my frenglish

6

Lakewakes  offers a good tip… With the use of perf. ply plastic film…

S-glass is going to whiten carbon a bit for sure, probably more-so in the “bag”

I over saturate the cloth when I laminate, and don’t over work the resin into cloth to a point of it frothing…

Don’t try to remove as much excess epoxy with your squeegee as you would a hand lam, but let the bag do the work instead…

This is very important on darker colors, ask me how I know…

Anyway the trick to getting a clear glass job when  vac laminating dark colors, is to put on more resin than you need, don’t rush applying vac pressure ,allow the epoxy to kick ever so slightly so it doesn’t  all get pulled out into the peel ply quite as much…

The perforated film  Lakes mentions insures that you don’t pull out too much resin, but with practice you don’t need to use it…

I laminate my glass on at 22" to 26" of merc. or around 10psi. , and it’s still clear… Lower or higher bagging pressure has little influence on clarity…

I build full sandwich so you can bag at this higher pressure without crushing the board… I don’t pressurize this high to remove the max epoxy, but simply to flatten the shit out of the cloth resulting in a stronger mechanical laminate allowing you to use more layers  of lighter cloth… But that is a different topic ,Sorry…

The structural advantages are worth the effort, as Mike mentions above…

I like carbon or carbon kevlar for exotic cosmetic looks… But carbon is too stiff to use in my applications especially with S-glass, as Mike also mentioned…

Any glass over carbon should primarily  be considers as a sealer layer that reduces the chance of the carbon exploding and cutting your feet to hell if the board ever fails…Pure carbon boards are a little spooky that way…

If you’ve ever seen a 100% carbon fiber sailboard mast explode, it’s quite a sight !!

7

Kiterider,

So you use perforated plastic between the lamination and the peel ply,  Let the epoxy cure past easy-flow into slightly set before pulling vacuum.  and pulling 10 psi.  Thanks! This works for clear over carbon.  Does it work for tints also?

thanks,

Mark

8

The peel ply should always go directly against the laminate, then the perf plastic on top of that.

The perf plastic shreds when you try and peel it, so would be an absolute b*tch if it was against the laminate.

The peel ply stays together pretty well, depending which variety you use, and the point is that it prepares the surface for subsequent mechanical bonding operations (hotcoat or further laminates).

I’ve never achieved a TRUELY clear bagged laminate (Infusion excluded) with eglass or any other clear cloth… not totally perfect like you can get a hand lam.

There’s always some air bubble or hint of the weave showing. The carbon might hide some stuff, but any white flaws will show as you’ve said.

I’d love to talk to someone who can do it perfectly and consistently - I’m not saying it can’t be done, just that I stopped trying and ruining laminates before I found the magic formula!

I only bag exotic cloths now, a perfect cosmetic finish is too important for clear lams! Carbon, kevlar, innegra etc are fine to vac on their own.

9

I never used peel ply just the 1 mil perf film cause it bends corners real well. I let my lam sit in the bag over night 12+ hours so it gets real hard. The perf film them comes off easy. I also like to reuse my tube bag (27") for 3 or more boards so the lam can’t feel sticky or it will rip the bag. The 2oz breather pull just enough of the resin off. I had started with 4 oz years ago and ended up with dry finish , so I switched to the 2 oz. I will also reuse the perf. Film per board . I just brush and shake all dried resin off.

Mark

10

You just saved me a nightmare!

 

11

So lakewakes,  you use the breather to absorb the epoxy, not the peel ply?

So far, it seems we’re all in agreement that the amount of vacuum is the key to clarity.  Just enought to absorb the extra, without squeezing it dry.  And the level of vacuum would differ with the peel/ perf/ breather/ fiberglass combination.

 

I think I need to make up some test samples.

12

Cosmetics (especially clarity) and ultimate physical properties for composites are for the most part working against each other. There is a world of literature on the production of composites with ultimate physical characteristics and in those cases cosmetics of the actual laminate are rarely considered.

For good cosmetics, sacrifices/compromises have to be made. For all practical purposes, that means a slightly resin rich laminate as compared to one with the absolute highest physical properties for a given thickness etc. (yes, that statement is from a guy who sells epoxy, but it still happens to be true!)

If you read kiterider’s post carefully, you will find that he is cleverly manipulating the resin/fiber ratios to give good cosmetics. We do something similar to yield clear laminates in a system that uses 6 bar (87 psi) pressure on the part. There is a measurable loss in physical properties versus a less cosmetically appealing laminate, but not so much that it detracts from the performance of the part. A good amount of trial and error is needed to dial in a particular vacuum or pressure laminating system.

BTW, in response to Mike’s statement that s-glass is notorious for showing weave, it is physically impossible (ie based on physics known for about the last 1000 years) for any resin system that produces completely clear laminates with e-glass to also produce completely clear laminates with s-glass and vice versa.

Rob

13

So Rob,

What is your recipe for water clear S cloth?

14

@ Everysurfer,

Yes I use the breather to soak up the resin. I actually use a 3# foam core for my builds and a 2.2 innegra cloth. I mix my GR epoxy to a medium 50/50 hardener so I have up to 30 to 45 min of work time. After I fold the laps on the board then I lay the 1 mil perf ply and fold it over the rails to opposite side then I wrap the 2 oz. Breather over the perf ply then it goes into the bag. With 3# foam and 2.2 innegra I can squeeze it down to 10 to 12 hg without getting dry weave. A non innegra 3# build I use 8 hg on my builds with a 4/4 or 4/6 cloth…

I wish I could lam both sides at the same time, but I think I could not get a tight lap .

For lighter foam would use 6 hg or lower.

15

Hey Mark,

Perforated film goes between the peel ply and breather strictly for the purpose of further controling , or fine tuning the amout of excess resin removal for a more cosmetically appealing surface…   It’s redundant if you control the bagging time,  pressure,temp and such… The resin never really cures, it’s just not as wet as when you first spread it on the fiberglass… It’s a feel thing…

I just don’t panic and rush to get the board in the bag, it seems to work well enough… The glass has slightly thickened up, but not as much as my first post  might  have suggested… 

Like robw said…It’s a trial and error thing …And a fine line to walk between ultimate cosmetics and ideal vacuum bagged composites… Hey… I do my best, and it ain’t perfect, but I end up with a decent compromise…I used to do maximum cloth to resin ratio vacs.  then paint… Now I leave in some resin and no  exterior paint…    ( Thank’s for the props. robw… Clever no,  just trial and error…)

10 -11 psi. vac is  quite a lot for most  surfboard foams under 2# density and I’d be hesitant to try it on  2#  or even  2.1 # … I’m not recommending that for unskinned foam…

We all have little hard learned discoveries that we feel we need to protect, and mine might not be unique…

With that in mind, I sat with fingers at rest for the last 5 minutes wondering if I should share a  tip  for clear, weave-less, vac laminates… I’ve learned so much valued and much appreciated info. from this site and I enjoy sharing, I don’t wish to be selfish…

Anyway… It’s the use of multiple layers of 3oz. or even 2.4 oz. finely woven e-glass instead of a more coarsly and common woven 4oz or 6oz…

The fine weave stuff just seems to disappear… If you were to hand laminate with this stuff  it would just float on the epoxy and result in a shitty , bumpy, non tight lam just waiting to de lam… Unless you worked it really well…     Put it in the bag at  22" to 26" and  so long weave pattern, hello super tight,  even looking cloth…

.It just looks better up close.

I lay 2 layers of 3oz. diagonally on the deck in a home -made  60 to 70 deg. bi axial pattern, capped with a third layer running north to south… Bear in mind these are kite-boards…

16

Everysurfer:

Your  question is directed to Rob…

But may I answer simply :  Use e-glass… S-glass is great stuff, it’s all I used once opon a time… But why bother, e-glass is more than good enough for what we do and S-glass exhibits too much in the way of stiffness when combined with carbon as Mike originally mentioned…

I can buy a whole roll of 3.2oz e-glass for about the same amount as 10 yards of 4oz. S…  On the basis of cost differential alone, I don’t see the point in S any more… I can invest in high quality Core-Cell skins or bamboo veneer for an ultimately stronger product… But this again is a bit off topic…