I realise there is a lot of information about bagging in the archives, I have read most of it I think!
Today I popped my bagging cherry! I spent all morning getting everything ready, planning what I was going to laminate, and the order all the vac bag bits go together, I took my time with the lam and was generous with the resin. My first problem was putting the peel ply on, I couldn’t get it to sit on the tacky lam without creasing up, I went ahead and bagged it all up and left it on about 7hg for a couple of hours.
When I took the bag off and peeled the ply (that stuff is hard to get off) the glass was bone dry, with more than a couple of dry spots and covered in creases! The glass is so dry it’s going to be difficult to sand down the creases without sanding through.
I also made the mistake, despite reading that one shouldn’t, of putting the breech unit on the blank, it has rather predictably left a mark. I’m hoping that the fill coat with hide most of these cock ups. Any advice would be very gratefully recieved indeed!
I always run my vaccum on the dry side, never on the wet side. I run a strip of breather the length of the dry areas. Running my vacuum on the dry side allows me to pull the bagging material smoothly over the entire wet side, including the rails.
I also tape my peel ply down so it doesn’t wander or bunch up.
Lastly, I use masking tape directly over the lamination on the nose and tail to ensure the perfect fit with no gaps or wrinkles. You just gotta pull the tape off while the resin is still in the B-stage, otherwise it’s tough to get off.
A picture might convey it. New bag directly against the wet lam and stretched tight during the draw down so there are no wrinkles in the lam, nose and tail are taped with masking tape (mummy-style) so there aren’t any marks. I did not fill or sand this deck. I only filled and hand sanded the rails. I never even came close to touching the cloth when it finished it. . Came out nice.
One side of the board is being laminated, so it’s “wet”. The other side of the board isn’t being laminated (and it’s facing down) - I call that the dry side. I bring my vacuum onto whichever side is facing down.
I only do that with epoxy. It works whether you’re using vacuum or not, and the tips/edges always come out clean and extra well covered with little or no sanding required. This pic shows a little more clearly how I do it for vacuum bagging. I lay down the cross piece first then start in the middle and work my way out, overlapping it like a mummy.
Why do you vaccum bag lam ?
If it’s for use less resin for lam glass it’s not effective except if you lam many layers at once.
If it’s for more strengh for a surfboard skin it’s not effective too because low resin/reinforce ratio only increase tensil strengh/weight ratio and surfboard skin break because of flexural stress ( exactly buckling instability). For Increase skin buckling stability you have to increase skin stiffness, use stiffer material and or increase thickness. By compacting lam vaccum bag reduce thickness without increasing stiffness, all bad. And by drying lam vac bag increase porosity off lam, not good too.
Mostly it’s just something I have wanted to explore for a while, from an engineering perspective as much as anything else. I think there is an application for vacuum bagging, especially in SUP manufacture, where keeping weight down is key. As you said, where using multiple layers, or composites that are difficult to hand lam. There are lots of people out there getting great SUPs out of the bag, so there has to be something of merit in the process right?
I found you can scrape those bag wrinkles off with a razor blade and the hot coat will make them disappear. Like it has been said, don’t use too much vac pressure.
I vacuum bagged that board because I was using innegra, which actually works better when bagged under vacuum. Greg Loerh said a long time ago that it’s tough to beat a well-done hand lamination, and - within the context of using regular surfboard fiberglass and resins - I believe him.
Nope, nope, nope. A bagged lam is better than a hand lam, because when done right, you are replacing low strength surplus epoxy weight with high strength cloth weight.
everysurfer is correct. Also the"wrinkles" in peel ply will cause a raised resin bleb above the lamination and not a wrinkle in the fiberglass. Don’t be discouraged w-jack. Even with all the info you read on line researching your first try there are probably another 100 variables that could not be described in the posts and only learned with trying.
Your peel ply thickness and ultimate absorbancy could be one problem. Also your epoxy choice in regards to viscosity could be another. Like suggested above I also tape my peel ply to make taunt. Also I suck my bag quickly to about 3/4 final pull then hook to pump and stretch out wrinkles of bag while getting to full vacuum. Second epoxy coat and a sand then final coat will make it pop nicely with the finish.
Pics below I was doing everything wrong a few weeks back. Look at all those wrinkls in the bag!!! Never, as in NEVER have had a problem pulling peel ply off. Smooth results in my opinion. Disclaimer-texalium is like cardboard. would have to try to wrinkle this stuff. Same for certain carbon fiber and kevlar combo’s. Straight up E fiberglass I have never tried.
Hey Everysurfer. I’ve been vac bagging my lams(multiple layers of cloth at one time). Thought it made the lam stronger & lighter by optimizing resin to cloth ratio ( as long as you don’t pull too much vac…I try for 10 to 11 inches Hg.)
Lemat’s respnse above says not to bag. Now I’m confused. The boards I’ve bagged before seem plenty strong & light.
Greg- the one “big board” I built with Innegra , I vac bagged. I sopke with a Tech Rep @ innegra & he specifically told me to “bag it” as the innegra doesn’t absorb eopxy very well. Are you sure?
This is where I put my foot in my mouth, and go down in flames.
Lemat says he is a professional engineer, engineering teacher, and professional board maker. So I’ve got to assume he knows what he is doing… He bags his boards… But at the same time he tells others not to… He also has a secret lamination process… He has also posted that laminating nylon like C()!l does is no stronger than epoxy alone…
So I have to wonder if some of what he posts is misinformation…
Yes, bagging boards is more labor, but you end up with a much stronger and lighter board.
I hate to advise against the rep, but the function of innegra and other similar bulkers is to separate the inner and outer layer of woven fiber. I’ve not had a problem with it absorbing epoxy. Epoxy is all I use. However, like Everysurfer and Dwight, I use a wet-out table to wet it out (very lean), then roll it up on a 4 inch diameter length of PVC pipe then roll it out on the board. I’ve also found that bagging innegra subjects it to wrinkles within the bag that are near impossible to get out before it sets. With an open lam on the innegra, you can tweak it with razor blades to get it to lay flat. Just my 2 cents. Was the rep building surfboards or sailboat hulls? check back and see if what I’ve suggested makes sense to him. I would love to know if I am mistaken. thx
My innegra lams all came out of the bag super flat because I run the vacuum from the dry side and I pull the bag completely flat over the rails from the bottom. And I use a new bag straight off the roll with no wrinkles in it. I figured out that was only slightly more expensive than using the better peel ply, and a lot faster/easier. No cutting or taping.
I had one lam where the innegra cloth had some wrinkles in it prior to glassing and although the bag pulled it flat the imprints from the wrinkles printed through visually (I was pissed). That taught me the practical limits of vacuum bagging. Leastwise with my technique. On the next one I ironed the innegra prior to using it - that fixed that problem.
I didn’t even fill or sand the deck on the last one, and I only applied a light finish coat to the bottom in order to have enough to block sand it.
It’s like everyone was saying about innegra, the boards may feel like they’re bulltetproof but when it’s sandwiched between layers of 4oz they do come out heavier so it ain’t free. I probably won’t do any more unless it’s with a design that I would normally glass with 6+6 x 6 PE . The industrial look is cool, though.
Yup. I run a strip from nose to tail and well inside the lapline. I tape that on after I lay my lapline tape and before I start glassing.
For the innegra, I usually laid that out first and cut it so the sides would just barely clear the tapeline for a 1" lap. Then I wetted it out - fairly dry. Then I laid a dry uncut piece of 4oz over that and squeegeed that until it wet out from what was left in the innegra. There will be a few spots where there’s not enough resin left in the innegra to wet out the cap, so I just dab a little resin into those areas so as to not leave any dry spots. If my technique was better I probably wouldn’t have to do that. At that point the cap is barely wet.
Then I cut the cap so it’s edges are maybe 3/4" longer than those of the innegra. That way I can tape the dry edge down in a couple spots along the rail line so as to make it easier to slip the board into the bag without catching.
The vacuum draw down forces the resin through the cap. If my wetout of the innegra was about as dry as I could get then I end up with about a 2/3 fill texture and no dry spots. That’s how I know I’m not using too much resin.
