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vac pumping fiberglass, what plastic

Discussion in 'The Lounge' started by darkshadow, Apr 9, 2007.

  1. darkshadow

    darkshadow 1 ton status

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    A trick in fiberglassing odd shaped pieces, is to bog it and hook the bag to a vac pump, sucking the are out and holding the form.

    does anyone know what kind of plasitc is best? can I use regular old 6 mil poly, or must it be something elce so it wont stick?
     
  2. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    ummm, are you sure this is something you need to do?

    Vacuum bagging is a huge subject... There is tons of info to it.. Complex shapes are not easily bagged... The simpler the shape, the easier and more effective bagging is.. The purpose in bagging is for uniformity and more importantly, a good resin to glass ratio for best strength.. Also, 98% of the time, a mold is required to even consider bagging...

    bagging material can be as simple polyethelene plastic from homo depot to highly specialized nylons and rubber...

    you need to either use a breather cloth and release film or you can use a release fabric like Peel Ply under the bagging.. You cannot just put plastic..

    You'll also need some sort of checkvalve, sealant tape, let alone a vacuum generator... This can vary greatly... a shop vac can work, but it's barely doable... most decent vacuum pumps that i've priced run $300 to $1000... You can get systems that use compressed air to create vacuum, this is the route I'm going...

    Obviously with my dash production in the hopefully, not too distant future, I've been reschooling myself on the subject (hadn't done it in a few years) and the technology available these days...

    What are you trying to make?
     
  3. Beast388

    Beast388 1/2 ton status

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    At work on our reuseable bags, we use a special silicone that is resistant to the corrosiveness of the resin. Our subsidiary company still does the old-fashioned "vacuum bagging" process and they use a thin plastic sheet, but I'm not sure if it is poly or something else. I will ask and find out.:D
     
  4. Beast388

    Beast388 1/2 ton status

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    Paul, you obviously have some experience or at least have some knowledge about vacuum bagging. We are doing a large scale project for a customer using the resin infusion process and are currently expanding to add capacity. All of the experts in the field said we'd never be able to produce the part that we have so far produced thousands of. It is pretty exciting technology to say the least.:D
     
  5. darkshadow

    darkshadow 1 ton status

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    I KNEW I Should have asked you@!

    I was thinking shopvac, atached to the plastic with a "neck" of plastic so it could be taped off.

    it doesn't have to be perfect, i was more interested in bagging so the cloth would stay inplace.

    Don't laugh but it is a canoe, this canoe has been in ALL water all around north amarica, from the gulf to northern canada, out west every ware!

    but it has seen some ware and had a lot of half ass patchs on the keels, and bottom. I used a grinder to sand thru all the patchs and the whole bottom is now to the origanal glass.

    I have found the cloth likes to lift around the keal, when i used heavy cloth to beaf the worn keal back up. I have some nice tight cloth i want to lay over the whole bottom and i thought about bagging it, By laying poly over the bottom and duct taping it to the sides.

    what if I sprayed the poly with wd-40 or somthing, would that make the poly not stick to the glass? or the shop I got the glass from has releasse wax for molds, would that work?
     
  6. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Always cool when your doing something cutting edge..

    I'm still up in the air on whether I'm gonna bag my dashes... if I don't, I'll still be using the Peel Ply anyway to help control the resin to glass ratio..

    The baddest sh*t is that composite glass my box is made of.. machine extruded, sick product...
     
  7. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    just use pva... release agent... water soluable fluid, you spray or brush on.. by far the most effective.. cheap and easy...

    high weight clothes will do that...

    use a bondo spreader to drag out the resin and keep your edges down... usually i'll use a fiberglass roller, then a spreader..

    just an fyi, you don't want tons of wet resin, you want mostly cloth, just thoroughly saturated.. thus what vacuum baggings main purpose is, drawing out resin..

    maybe take some pics and shoot me a pm, we should be able to come ujp with something simple and effective...
     
  8. Beast388

    Beast388 1/2 ton status

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    So are you going to wet the glass matte first, then lay it on the canoe? If so you will probably need to use a slow catalyst so that you have a decent working time. You don't want any of that to start kicking before you are ready. A slow catalyst also exotherms less, which means it will stay cooler as it kicks. If you get too hot, you might warp that canoe body.

    Another thing is that you will need some way to exhaust the excess resin. Whether you use a catch can on your vacuum source or screed it out (like our sister company does) will probably depend one the part shape. If you are going to duct tape the bag to the canoe then you will most likely need a catch can.:wink1:

    Our sister company drags all of the excess resin to an area out side the trim of the part. In other words, they drag to an area that is cut away and discarded. To me it doesn't sound like you will have that option on your canoe.
     
  9. darkshadow

    darkshadow 1 ton status

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    Would the peel ply help keep the cloth in in corners of the keels?

    the canoe has 3, the main is at least 3/4 thic and 1 1/2 tall, the sides are 8" away and only 1" high.

    SO if iI squigie the cloth in with the peel ply, would that beef it up enuff to keep from moving?

    I dont want a ton of resin no, dont want it too heavy, just want to tie the whole bottom in one shot to add strength, and really don't want it going to **** on me. going to call my local shop see if they carry peel ply.


    also another question, the gal of resen i got has been in my unheated garage all winter, would that efect it?
     
  10. darkshadow

    darkshadow 1 ton status

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    beast by what i have read about peel ply, i should be able to get away with out bagging.

    I figger i could remove mose of the resin squigieing it out of the area i am doing.

    for this i think I would position the cloth where i want it and pour the resin over it useing a spreader to force it into the cloth.
     
  11. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Do you know what weight the cloth is?

    Your resin should be fine, just stir it up good...
     
  12. darkshadow

    darkshadow 1 ton status

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    No.

    I think each weave is 1/16" wide.
     

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