lauan plywood voids

Discussion in 'Materials' started by samindanang, May 21, 2014.

  1. rwatson
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    rwatson Senior Member


    yes, it does - the downside is that it wrinkles badly, and cannot be smoothed out to a flat surface.

    I often use it in small patches when i cant be bothered do it properly.

    Thick builders plastic stays less wrinkle free, but its hard to use unless you have a perfectly flat bit to lay it on. Fabric can be smoothed and teased to lay out on a compound curve up to say 2 or 3 square metres.
     
  2. UNCIVILIZED
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    UNCIVILIZED DIY Junkyard MadScientist

    rwatson, I'm confused, are you saying that your average Visquine which you can get at the hardware store doesn't work well as a tool to assist in fiberglass work? And if this is the case can you please clarify, as this goes counter to a fair bit of my experience with it.
    I can understand your reply about cling wrap, but not this. Thanks.
     
  3. rwatson
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    rwatson Senior Member

    I have no idea what Visquine is.

    If its a relatively thick plastic, it is what I was talking about when I said "Thick builders plastic stays less wrinkle free"

    However, i personally have yet to find a pack of builders plastic ( without buying the whole roll) that doesnt have significant permanent creases in it.
     
  4. PAR
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    PAR Yacht Designer/Builder

    Visqueen (correct spelling) is what us old timers call polyethylene plastic sheeting. Commonly, 3 to 10 mils, with 4 and 6 mil being the most widely seen.

    I too have a fair bit of experience, with these clear plastic sheeting materials and in the heavier weights works pretty well, though wrinkling can be a problem if you don't secure it somehow. I've taped it or stapled it to plywood, to use as a pad to clamp a glued assembly, but more recently I've switched to spray adhesive to secure it to things. If used as a drape, to keep things off of wet goo, it can wrinkle on compound surfaces and with the cure's exotherm.

    On things I want to keep smooth to speed up fairing, I'll use Mylar instead of Visqueen, as it's much stiffer and available in heavier weights. Of course compound curves need to be "stripped" much like the veneer arrangements on a cold molded build, but it can speed up smoothing and fairing operations.

    Bubbles under the wrap can be a problem, so I use a rolling technique to eliminate as many as possible. This understandably becomes problematic on larger areas.

    I very rarely will use any sheeting material over a fillet or cloth covered fillet, finding it's just not worth the bother, compared to good technique with a plastic applicator, fillet stick or similar. Getting a fillet to smooth out gets easier the more you do and you'll develop techniques that work better then others. I use the tape on either side of the fillet method, previously described, but only when I need a neat, visually uniform fillet. I've found the filler and viscosity, in the fillet mix are the keys to an easy time making a sweet fillet, even if covered with fabric. You can be too coarse with the fillet material and also too dry, both of which can cause tools to drag, even under fabric. This is all just goo time. After a few hundred feet of fillets, you'll get a clue about consistency and material combinations and percentages. This kind of sucks for the first build, but if you count up all the linear feet of seams you'll fillet, you'll be close to having enough under your belt to get reasonably good at it.
     
  5. UNCIVILIZED
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    UNCIVILIZED DIY Junkyard MadScientist

    Thanks for those clarifications. And PAR, yes, that's the kind of plastic to which I'm referring. Albeit, I use it primarily as a surface upon which to lay the cloth for the cloth's wet out, as well as to carry & or carry/maneuver wetted out pieces around to where I want to place them.
    And yes, I'm familiar with the problems which the plastic can cause if left in place as a laminate cures. It's not something which I commonly do, just for those reasons.

    Also, we're definitely on the same page with regards to filleting. AKA, get it right to nigh on perfect the first time, as sanding (it) bites.
    I just recently did some reading about how they lay on a layer of veil cloth impregnated with a filleting blend, as the final layer when autoclaving with pre-pregs. And how perfect a finish it gives them. Interesting stuff, & something to try/test, the next time I do some vacume bagging. That, & or time to visit a spar maker for a tour.

    Thanks,
    Andy
     
  6. rwatson
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    rwatson Senior Member

    Thats not what I find. Filleting can benefit a lot from some kind of covering process. Particularly where you are having to reach into awkward corners with limited access.

    While you can spend a long time fritzing around with spatulas and other tools in constrained places, its much easier to cut out some small ( say 4 x 6 inch ) squares of plastic or similar, lay them along the 'groove', and smooth them in place with a gloved hand and or hard edge.

    It makes short work of a difficult job, leaving a snag-free inner join.

    The same applies for many other filleting jobs - because filleting perfectly requires a fine degree of consistency, and often its just easier to mash it into the groove, apply the fabric and make an easy job of leaving a nice, smooth uniform fill.
     
  7. PAR
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    PAR Yacht Designer/Builder

    I find it's technique and tool choice. The interface of a cockpit seat riser and the cockpit sole would be a place where I'd want a dead nuts uniform radius, so I'll use a ball mounted on a stick, probably with tape defining the edges. This produces a dead bang constant radius.

    I rarely work with wet cloth, having to take it to the work, but usually wet the cloth on the work. I find dry cloth so much easier to handle.

    The only time I cover a fillet with something other than 'glass fabric is in aesthetically sensitive areas and these are usually cosmetic fillets, so easy to sand. I will cut up bits of Mylar to make sanding easier, but mostly it's tools and technique. Simply put, I find it faster and easier to take a small drum sander (or whatever) to a fillet, then to have a lot of little pieces of plastic to pluck out and touch up.
     
  8. oldsailor7
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    oldsailor7 Senior Member

    +1 Par.
    I just usually use a popsicle, or choc ice stick, depending on the radius I want. :cool:
     

  9. PAR
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    PAR Yacht Designer/Builder

    The thing I don't like about shaped sticks is you can't move the angle, as you drag the tool along or the radius will change. With things in the way and the usually confined spaces on a boat, having to change the fillet tool angle as it's dragged through the goo is common, so in these cases, I use a ball on a stick, of course only if the fillet will be seen and needs to be pretty. If it isn't to be seen, the most common tool I use, is a plastic applicator and I bend it with my thumb and fore finger, though a shaped stick can work well too, in these places.
     
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