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Thread: Lamination question

  1. #1
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    Lamination question

    I am working on an assembly table, and need advice about putting plastic laminate on it. The top will be a lamination of both 1 1/2" thick LVL, with a piece of 3/4" plywood laminated on top of it. This is because I want to create a rabbet on a couple of sides to accommodate a Kreg mounting rail on the front and sides of the table top. I then want to put plastic laminate on the top of the plywood, to make for a nice slick surface.

    My question is, do I need to put laminate on the bottom too? I am sure if it was a thinner top, I would need to, but in this case, do I need to?

    Eventually, it will be perforated with bench dog holes which is why I am looking to make it so thick.

    Thanks, Doc
    As Cort would say: Fools are the only folk on the earth who can absolutely count on getting what they deserve.

  2. #2
    What makes you think the laminate on both sides is necessary? I don't see any reason why you would want to or need to. LVL and plywood are both very stable products to laminate to. The LVL might not have the greatest texure to adhere laminate to, but you could probably mill it flat enough.

  3. #3
    Do both sides for a balanced panel. Plywood has little movement but LVL has a long grain with movement across the grain. Align the scratch pattern on the back of the p-lam with the grain for best results. The laminate may or may not crack on the ply, winter to summer. Expansion and contraction of p-lam closely match that of MDF with humidity changes. No match at all with plywood.

  4. #4
    Greg,

    Most professional laminate suppliers will have what is called a "balance sheet". Thin, and no slick surface, made specifically to do what you describe. The stuff I've got is brown, quite ugly, but has done the job well, as I have several shop fixtures that are still nice and flat after 25 years!

    Bob

  5. #5
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    That is the operative question. I have always been told that you should put laminate on both sides to keep it balanced. In this case, is it necessary?
    As Cort would say: Fools are the only folk on the earth who can absolutely count on getting what they deserve.

  6. #6
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    Formica and plywood have essentially zero expansion and contraction with humidity changes. LVLs, because the grain is all running in the same direction, do have the threat of shrinking cross-grain. If you laminate plywood to LVL, you may get cupping as the LVL shrinks and the plywood does not. The formica, which I'm guessing you're going to glue to the plywood, doesn't really change the situation.

    To avoid the LVL shinkage issue, you might employ more layers of plywood instead of the LVL. Then you'd have a stable substrate for the formica.

  7. #7
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    That is different than my impression of the LVL. I had always been under the impression that LVL is like thick plywood, as the layers are at 90 degrees to each other to make up the product. That, and the fact that I have a bunch of offcuts from the construction zone next door, is why I want to use it in the first place. I know that Megan Fitzpatrick of Popular Woodworking used it in a workbench a couple of years ago to see how it would do, but she did not use any laminate on it. I will have to research that issue further.

    Doc
    As Cort would say: Fools are the only folk on the earth who can absolutely count on getting what they deserve.

  8. #8
    Formica is a wood product (paper) and expands/contracts a lot, more like MDF than ply. Ply moves very little.

    Quote Originally Posted by Jamie Buxton View Post
    Formica and plywood have essentially zero expansion and contraction with humidity changes. LVLs, because the grain is all running in the same direction, do have the threat of shrinking cross-grain. If you laminate plywood to LVL, you may get cupping as the LVL shrinks and the plywood does not. The formica, which I'm guessing you're going to glue to the plywood, doesn't really change the situation.

    To avoid the LVL shinkage issue, you might employ more layers of plywood instead of the LVL. Then you'd have a stable substrate for the formica.

  9. #9
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    Quote Originally Posted by Steve Ryan View Post
    ...Formica is a wood product (paper) and expands/contracts a lot....
    While formica has paper in it, it also has a whole lot of plastic. That's why it is so impervious to water. You can leave a puddle of water on a formica counter until it evaporates, and there will be no effect on the formica. If it were just paper, that wouldn't be the case. Because it is waterproof, atmospheric humidity doesn't penetrate into it.

  10. #10
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    Quote Originally Posted by Greg Hines, MD View Post
    ... LVL is like thick plywood, as the layers are at 90 degrees to each other to make up the product. That, and the fact that I have a bunch of offcuts from the construction zone next door, is why I want to use it in the first place...
    True LVLs have the grain direction going the same direction in all the layers. They're mostly used as load-carrying beams and joists and rafters. If they were made like plywood, the layers with the grain running vertically would not contribute materially to the stiffness of the beam.

  11. #11
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    It sounds like I will be putting the plastic laminate on both sides of the plywood, then screwing it to the LVL before boring dog holes and other measures. I did not realize how much movement the LVL would have.
    As Cort would say: Fools are the only folk on the earth who can absolutely count on getting what they deserve.

  12. #12
    Quote Originally Posted by Jamie Buxton View Post
    While formica has paper in it, it also has a whole lot of plastic. That's why it is so impervious to water. You can leave a puddle of water on a formica counter until it evaporates, and there will be no effect on the formica. If it were just paper, that wouldn't be the case. Because it is waterproof, atmospheric humidity doesn't penetrate into it.
    Totaly wrong. It will absorb water right through the face and will expand just like a piece of wood, and also dry out in dry winter conditions and shrink. It is mostly paper and the paper has a grain like most papers. The grain follows the sanding scratches on the back of the sheet, but is not otherwise related to the scratches. It will expand across the grain more than along the grain just like a piece of wood. Put some heavy gloves on and tear a piece. The tear will easily follow the grain. Wet the back of a piece of p-lam and it will curl. Soak it for a period of time and the sheet will be just about useless for fabrication. The best core for p-lam is MDF, followed by particleboard because they are a good match for expansion/contraction with humidity. Plywood is next to last with drywall being about dead last.

  13. #13
    Assuming that "Formica" is the same material on both sides of the Atlantic then yes, it is based on a sheet of paper but the paper has been totally impregnated with resin.

    I have never seen Formica - or any other decent quality laminate, react to water.

  14. #14
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    All the "Formica" or "plastic laminate" I've used or seen is impervious to water. It is plastic, basically.
    Wood: a fickle medium....

    Did you know SMC is user supported? Please help.

  15. #15
    Quote Originally Posted by Chris Padilla View Post
    All the "Formica" or "plastic laminate" I've used or seen is impervious to water. It is plastic, basically.
    P-lam is mostly paper. 5,7,or more layers of resin saturated paper. Top layer in saturated with melamine, or a more chem resistant top layer for lab grade p-lam. The sheets are saturated in dip tanks traveling on a series of rollers that dip, roll, dip again and finally travel through an oven that looked to be well over 100 feet long. After the saturation process rollers, the paper is conveyed through the oven on heated air jets, in an up and down zig zag path like a snake. Nothing touches it after the rollers. At the end of the line the dry paper is cut into sheets and stored in a very controled temp/humidity room. These sheets are sent in stacks to the press line where a release sheet is put down, 5 or more brown sheets are layed down, color sheet layed down, and often a very thin sheet with the melamine layed down. Top it off with a textured stainless steel sheet for the pattern (wood grain, matt, or gloss, etc) and repeat until book height is reached. Into the press it goes for cooking. 2 men were laying up the sheets and they were very quick. Steel sheet was placed by robotics. I processed so muck p-lam that Wilsonart flew 2 bussloads of us fabricators to Texas for a 3 day tour of the plant. All expenses included. I have also visited a melamine plant in Atlanta where they also produce their own saturated papers in a sim method. Tech guiding us on that tour told us that when a forklift operator went missing they would always find him in the enormous paper storage room. Plant was hot as could be but the storage room had to be cool and dry.
    Try looking here. Wilsonart has sim tech data.
    http://www.formica.com/documents/Tec...de101220_1.pdf
    The late Art Betterly (of the tool company fame) was an engineer who did a ton of work with Formica corperation on stability of the product and proper substrates. I was privelidged to attend 2 of his seminars and learned an awful lot from him. BTW, p-lam started out an electrical product made by the Micarta corp. The name Formica came about from FORrmerly MICArta. The trade name Formica became so very universal that the gov wanted to take the name away and make formica a generic name, and filed suit. Wilsonart stepped in and told the gov to buzz off. Smart move as Wilsonart was well on the way to becoming the biggest US laminate producer.

    Furniture shrinks in winter, even though we put many layers on poly (plastic) on it. Same thing happens with p-lam. Take 2) 24" squares and put a soaked newspaper stack on top of one face up, the other on top of sheet face down. Both will react to the moisture, although the wetted back will react much quicker.

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