Collecting suppies for my first vac job. Anybody have experience with Stretchlon bagging material? It seems real easy to use since you don’t have pleats. I found it on Fiberglasssupplies.com or http://www.fiberglasssupply.com/Product_Catalog/Vacuum_Bagging/vacuum_bagging.html
i have checked it out and keep thinking about using it, BUT it is really nice to see what is going on in the bag… i don’t think i have a good enough feel for the whole process to do it “blind”… pleats are no big deal when sticking down skins and rails… might really come in handy when doing an outer glass…
i started out with the 30ml bagging stuff from joewooder.com and it was a total pain in the ass for me… i moved on to the 2ml “tube” stuff and it works insane… my pump only cycles for about 30secs every 20mins…
I agree. I followed Benny’s suggestion and went with the 2 ml stuff it works great. I also went with the aluminum tape used for sealing ducts… so much better than masking tape!
I hadn’t thought about visibility being a factor due to breather material being opaque. I take it you guys aren’t using breather. The vac still distributes fine? It seems necessary to abasorb the excess epoxy for the best glass/resin ratio, or does it just suck into the corners of the bag? All the pressure without breather absorption seems like it would push the resin into the blank.
I mix a little more than a 1:1 ration, put the glass on the balsa, the resin on the glass, flip the whole thing over onto the foam, put it in the bag. For breather material I use the cheap shade cloth from Home Depot. There is no waste to slip out. This technique is so easy that I was able to put on both the top and bottom skin at the same time.
Are you bagging the outside layer of glass too?
Dan
what’s a 1-1 ration?
bleeder both sides?
I’d like to try both side too can’t figure out the air flow scenerio… you know cottom batting layer…
KeepOn
isn’t that stuff for pressure injection mold use?
Did the vacuum outside glass it’s hard… I think frozen prepreg like Kenz suggested would be a better option for exterior glass vacuuming.
I use the ACP tube bags but I’d like to try one of those 30 mil permanent bags from JoeWoodworker.
JoeW has better nipples than ACP too… got that one chippy?
Heres what I did and I was really happy with how it turned out. I think that it was no more work than just bagging one skin.
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Glued the rail strips with the CA glue and cut the bottom to shape.
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Glued one of the completed strips with gorilla glue to each side of the blank (I went with the 2"Home Depot foam and actually bent the foam to the rails)
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When dry I put glue to the other strips and glued them to the blank at the same time (I held it in place with duct tape)
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When dry I shaped the top and bottom (I just used saw horses to hold the board)
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On my workbench I layed out the top and bottom skin (glued with CA glue and a 3/8" strip of tape)
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Cut the glass to shape and layed it on the skins.
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Weighed the glass and then mixed a little more than the same weight in resin to make it a little bit more than a 1:1 ratio (I made one cup for each skin so I could add the hardener when I needed it.)
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Poured and spread one skin mixed the other batch and did the other skin
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Put the blank on the bottom skin then flipped the top skin on top of the blank
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Used pieces of masking tape to “pull” the to and bottom skins together so that they wouldn’t slid.
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Got a wide piece of shade cloth and wrapped the board like a taco and taped the edges together
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Popped it in the bag, sealed it up and let it go
I was so happy with how it turned out that I think I’m going to try bagging on the outer glass (now that might be some drama)
Oneula - Some of the reading I have been doing suggests using a perforated film to lay over the outer glass before vaccing. The perforations allow excess resin to seep through, leaving an optimal resin/glass ratio. The breather/absorbent material is layed over the perforated film and absorbs the excess resin as well as allowing the vac to breathe/circulate. The perforated film is also either slick or textured. The slick stuff leaves a finish that needs virtually no sanding for shiny finish, the textured stuff can be lammed over again with no need to sand for a good bond. It probably makes more sense ifo multiple layers of glass at a time, like boat molds, where theres a chance of significant excess resin. Weighing it all out and adding a bit extra resin sounds like a reasonable way to simplify with minimal extra weight. Good to hear you like JoeW’s vac connection I ordered one a couple days ago.
You can see thrugh the shade cloth pretty well then I take it.
1:1 would be oz’s glass to oz’s resin.
I’ve done all my outer glass laminations by hand.
With the under glass + sandwich core material (balsa, veneer, or d-cell), no peel ply is required.
I just use a bit of door screen to help the vac hose inhale:
So for the most part you guys are useing the vac bag to bend and keep your sandwhich core in place while the resin dries, rather than to get the best possible glass/resin ratio.
I have vacced the outer skins on the three balsa’s that I have done so far. First one I did bottom first and then deck, last two, bottom and deck together. Wet out the bottom as usual flip when still wet (don’t forget to polythene stands) and wet out deck, epoxy doen’t stick to stands like poly. I use perforated release film and had the best result using paper towels as a breather/bleed. Do not use peel ply (texture) as it will wrinkle like hell on the rails. Doing it this way, your laps are so flat you can hardly see them! To compensate for the thin breather, I usually insert a 1" plastic pipe in the full length of the bag, attached to vac pipe on one end, this is then wrapped in breather and if this is left in the excess bag and the bleed material over the lam is allowed to contact it, you should ensure that there is even pressure throughout the bag. I really believe that the vac is necessary for a better lam over balsa, even pressure and no out gassing of the wood!
I have no photos of my lam set up, but if anyone is interested I will take pics of the next board and post a sequence (within the next month).
btw I am usually running about 15 -18" Hg on my lam vac, anyone else care to tell me how much they dare to run on the outer skin?
Hope this helps
Cheers
Mark
Markyv
holes in the full bag 1" pipe?
how’s it pulling in the air?
That’s the issue I’m trying to solve in my head as normally you have breather on the opposite side of the board to pull the bag tight against the lam on the other side. I’m trying to envision doing both sides at the same time.
Maybe this is where Bert’s bubble wrap comes into play but thats a b"tch to work with plastic against plastic (bubble wrap sticking against bag material)
Maybe some type of breathable burlap is that what you’re using DanB?
KOKO
I used that perforated release film from ACP I got in error on my only attempt. And I’ll have to agree the finish is killer except for all the wrinkles. The issue is how do you keep the glass from moving around or developing air holes while you are trying to wrap it with the perforated release the release and then bagging it in a tube. Maybe the rocker table bag technique is better where you tape the plastic sheet to the tabletop. That’s why I think using prepregs is the answer for top and bottom exterior glassing in a bag.
Also you really need a slow kick off to do this. Only System3 slow seems to have a slow enough kick time to work on all this at once…
That does help, it seemed important to me too. I’m glad you mentioned 15-18 mmHg, I was planning on doing 10mm (just the number I remember reading some where). Obviously it doesn’t look too dry to you. You did a good job of describing the set up but I would like to see pics, particularly the lammed board with release film in place about ready for paper towels and vac bag, and another in the vac bag before the vac is applied. When you lam top and bottom at the same time, do you use the same batch of epoxy or two seperate batches? Do you stick the peel ply on the wet bottom glass before you flip?
I’ve used the Strechlon bagging material. It’s good in that it stretches quite a bit. The problem for me is the cost. It’s disposable. One little hole and it’s worthless. Sure you can patch holes with tape, but then you lose the stretch in that area. If you want to give it a try, call http://www.airtechonline.com/ and ask for a free sample.
The best bagging material is of course, silicone. It stretches 400% and is easy to repair, and has natural release properties. The problem is that it’s very expensive. It would be a good investment. My second choice is latex. 600% stretch and all the other properties of silicone except the natural release. It’s even available translucent. I haven’t tried it, but I think it’s worth looking into.
Then, there is the need for a stretch release film to prevent wrinkles. I just noticed that Airtech has something called Stretchlease.
If you don’t need stretch, you can’t beat the polyethylene tubing.
markyv… please post the photos of bagging on the outer glass… it is the next thing i am going to try, not at the moment thought, but at the end of Aug. when my crazy summer calms down… i am pressing on my skins at around 13" HG… bert has cautioned against releasing the pressure when bagging on the outter glass, are you using a vac switch system or a bleeder valve setup? can’t wait to give it ago…
here is some intresting bagging rubber on ebay…
I will post pictures, on this thread when I do the next board, will be in a couple of weeks if all goes well.
I mix separate batches for top and bottom, and don’t use peel ply at all. You can place some release film on the bottom before you flip.
Bert, as we now know infuses his boards, so can do it all in one hit without having to flip etc, I like to do it because it saves one more vac operation.
Some release films are more stretchy than others, go for as thin and stretchy as you can, I lay it out side to side with a small overlap at the rails, held with small pieces of masking tape, paper towel (from a roll) then stretched tight and taped. Pace board in tube bag,pull vac slowly and gather all the excess bag toward the bottom with the perforated pipe in the excess, not touching the board. Hard to describe but pics will make it easier. This is only how I do it, but as the release film is so cheap, as are paper towels I don’t feel the consumable bill is too high per board.
Oneula, the pipe has holes drilled in it, to allow air to enter its full length, pipe is wrapped in breather and inserted into bag.
I use a bleed valve made from a plumbing ball valve in a T union.
When everything is arranged nicely, I gradually turn up the heat! Although at the moment it’s a bit hot here to think about a lam without slow hardener!
One problem I can see is the elevated temps needed to cure the pre preg, the lowest temp that I have used is 90c, I wouldn’t like to put my newly shaped low density eps board under vac at that temp!! Nice abd easy to work with though.
Mark
Thanks for the update! I just picked up some perferated release film and plan to give it a shot (maybe tomorrow or Saturday).
I thought I’d bump this one up. I’ve been talking on the p.m. side about bagging with gloss finish out of the bag. Kenz was onto something nine years ago. Silicone bags. Except for the cost. Silicone is good for about 15 uses before it looses its release properties. At around $400 a bag, a little pricey.