bagging 101

Discussion in 'Fiberglass and Composite Boat Building' started by Tungsten, Jun 24, 2012.

  1. Tungsten
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    Tungsten Senior Member

    i have a few questions since i'm new to bagging,i'm using epoxy and looking at doing flat panels on a bench.

    when laying down the materials does it matter on overhang,so glass say 2" bigger, then peelply same? then perforated plastic then breather.does one material have to overhang the other?

    You don't see much talk about bagging wood or ply.should you pre wet the ply first let it cure then wet out and bag?also what kind of pressure do you need?
    if you wanted to do both sides of a wood panel at once how would you proceed?

    when bagging foam core do you need holes in foam if your only doing one side?also how much pressure?

    no doubt i'll have more questions as i do some tests but this will get me started.
     
  2. Herman
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    Herman Senior Member

    I presume you are making panels on some sort of mould (flat piece of formica, glass, etc).

    Use a good release on the mould. You will like it....

    On overhang: I like to make my panels slightly bigger than needed, to be able to cut them clean. You do not need much though. I like the peelply to be at least as large as the glass, the perforated film slightly larger, the bleeder the same size as the perf film. (it is a good idea to spray glue the perf film and bleeder together beforehand). This size setup helps in cleaning up afterwards.
    When doing wood laminations (as in wood veneers or ply stacked together), I like to mix epoxy with cotton fibers. Just a paintable consistancy, yoghurt type. Wetting both sides with a roller should be enough to do good bondings. Do some tests. On pressure: Use what you need, not much more. This can be surprisingly low.

    If you want to glass both sides of a wood panel, you can do both sides together, but it can be a bit tricky to keep things straight, depending on thickness of the plywood. You could laminate one side, add peelply, perf film and bleeder, then flip and do the other side. Alternatively you could do one side with peelply only, but then make sure you perforate the ply.

    Pressure is dependant on viscosity of resin and perf film hole size and spacing. A starting point is P3 perforation, and 50% vacuum.

    No holes needed for one-sided bagging.

    Keep us posted.
     
  3. Tungsten
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    Tungsten Senior Member

    Yes or a no for a mould,just a flat piece of wood(melamine),i was thinking i could tape the bag to this.

    No wood laminations just glass(6oz) and 1/4" ply so wet the wood first and let cure?

    spray glue perf plastic to breather why?

    not sure what the viscosity is, using east system epox. i no its thinner then system 3 its 1100.
    not sure on hole size or spacing of realese film don't have it yet.sold as"small" holes.

    P3 perforation??
    50% vac?? guessing 15Hg

    thanks Herman,
     
  4. Herman
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    Herman Senior Member

    Flat piece of melamine is a mould for me as well. You can tape the bag to it.

    Wetting out the wood and pre-cure it should not be nessecary, but take into account the amount of resin needed to coat the wood, when laminating.

    Spray glue perf film to bleeder: You will find out why when using it. It develops static energy, clings to itself, and can be a real pain. Glued to bleeder it is easy to work with.

    Use the small holes stuff. This probably is P3.

    50% vac indeed is 15 Hg, but I am "imperially impaired" :)
     
  5. Tungsten
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    Tungsten Senior Member

    ok good stuff,thanks again Herman.
     
  6. Tungsten
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    Tungsten Senior Member

    So i got my pump and supplies and ready to do a little test,i have a piece of honeycomb plascore 3/4" with the vail on it that i'd like to test.also have some corecell 1/2".How do i go about glassing the honeycomb?the piece is 12"x12".from what i read iwant to lay the honeycomb into the glass instead of the other way around.not sure. so upside down so to speak.

    i'll get some pics later today i'm going to do some dry tests to see how the vacuum all works.
    cheers..
     
  7. Herman
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    Herman Senior Member

    I hope you have the infusion grade, otherwise you might be left with a nasty surprise.
     
  8. Tungsten
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    Tungsten Senior Member

    Sorry Herman i'm not pickin up what your laying down?

    you mean the honeycomb?or the Corecell?

    also about this spray glue will your basic cheap arts and crafts type glue work or does it have to be the better stuff like 3m 77?
    and do i glue the breather to the release film on the side then lay it out?

    thx..
     
  9. Herman
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    Herman Senior Member

    Stupid me, you were going to wet-bag. In that case you can use the normal Plascore.

    On spray glue: use the cheap stuff. It is just to get the perf film to stick to the bleeder. Only after that cut out the size you need.
     
  10. Tungsten
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    Tungsten Senior Member

    So i got my pump and valves up and running and did some dry tests.I'm sure everyone has tried to seel a bag with single sided tape against a board.I counldn't get it too seel very good.

    Once i used the 2 sided bag tape it was much easier to get a good seal.
    I taped over the edge with single sided tape to seal a bit more but i think it was over kill.

    [​IMG]

    [​IMG]

    Which is the best way to attach the bag?do you put tape on melamine first then apply bag or tape on bag then apply to melamine?

    Also i found if i wetted the rubber seal on the bag connector or what ever its called i got a better seal.Anything else i could put on the gasket to get a good seal?
     
  11. Herman
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    Herman Senior Member

    Single sided tape is pretty useless. Use the real stuff: tackytape / sealant tape, or at low temp a butyltape.

    With infusion I usually put some tape around the hose, then insert the hose through a pleat.

    On your tape-on-bag or tape-on-tool dilemma: depends on the situation. For smaller stuff, where you can apply the tape on the bag on a table, this is easier many times. Large objects usually are simpler with tape-on-tool.

    Gasket: For wet bagging not critical, but a piece of sealant tape around the seal should do it.
     
  12. groper
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    groper Senior Member

    Tungsten, youve got all this gear setup now, i would encourage you to learn infusion rather than wet bagging - its much more versatile and you have infinite time to setup your peices instead of racing the resin gel time so, you can do much larger peices, it uses virtually all the same consumables wet bagging does with teh exception of the breather is substituted for flow media, you will use less resin with infusion compared to wet bagging and therefore it also becomes cheaper and you get lighter/stronger peices.

    Read the infusion Q and A thread, and search through all hermans posts - he has covered most questions and provided most info to get you started already. Go for it, youll be glad you did...
     
  13. Tungsten
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    Tungsten Senior Member

    ya groper i think thats my next step but i have to start somewhere.I need to figure out the bagging thing first and make a few mistakes and learn from that.
    hell i don't even understand most of the terms you guys use when you talk about infusion,so clearly i need a little time.
     
  14. Herman
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    Herman Senior Member

    Start whereever you want to start. Wet bagging is a bit more forgiving in terms of leaks, but indeed the geltime can be distracting. Just do a couple of small parts / sheets to learn and see the process. Even if it is just for fun.

    You will llike the cleanless of infusion. No messy resin everywhere.
     

  15. groper
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    groper Senior Member

    Fair enough, but in terms of difficulty, i actually find infusion easier.

    Wet bagging can be tricky... too much vacuum and you pull out too much resin and end up with a dry laminate... takes a little practice to get the amount of resin in your wet laminate consistant and then to find the right amount of vacuum to get the compression without drying it out too much... i find infusion much more forgiving in this respect.

    With infusion, provided you are completely anal about finding leaks and getting ZERO leaks, everything else is quite simple...
     
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