Wood magazine, August 1986, Issue No. 12 has plans for making table saw extensions. It has you adding plastic laminate to 3/4" plywood and a "balance sheet".
Quote: "Trace the outline of both extensions onto the balance sheet. (The balance sheet stabilizes the extensions and reduces the chances of warpage. If balance sheet is difficult to locate in your area, use laminate on the bottom side of the extensions)".
So, what in the h**l is a 'balance sheet'. Should I simply buy an interior 'door blank'?
Even with plywood it is good practice to do the same thing to both sides to avoid cupping and warping, so if you glue laminate on the face you should glue laminate on the reverse as well. That's a balance sheet. Brown laminate without the outer decorative paper is sold specifically for balance sheet and is sometimes therefore called --- ..... balance sheet!
Balance sheet is unfinished compressed kraftpaper/resin (phenolic), but it has a minute amount of porosity. It is basically laminate without the shiny/colour/top layer. Regular laminate as a balance sheet can be a bit 'too much' balance and warp the sheet the wrong way.
Ivan, you might check with a store that sells flooring tile. The very tough paper is applied to a concrete slab, using mastic, and then tiles are glued to it, rather than directly to the concrete. This is called a "slip," and helps to reduce cracks in the concrete inevitably showing through the tile above. The "slip" I've seen is a pinkish or greenish color and quite inexpensive.
FWIW, I've had good luck just applying several coats of clear finish to the reverse side of plywood to prevent warpage.
Against another piece of laminate I can't see how, either. Don't get more balancer than balanced precisely and unless there's an already-existing moisture differential thus entrained can't see how you would ever set up anything else unless exterior forcing like heating one side or something similar did it. Certainly the moisture differential for which it is applied to prevent widely differing rates from opposite sides can't be appreciably different afterwards.
Gotta jump in on this one since I've asked the same type question in the past and never got a real-world explanation.
How does one explain why all the commercial made table tops, counter tops for kitchens and baths and other major brand made furniture tops - do not have a finish / laminate or balance sheet on the underside?
I live in the area where Stickley furniture is made and if you look at their table tops and dressers and drawers drawer's, the tops or outsides are finished but the underside and drawers are not. If they are, then it sure is a clear coating that mimics fresh milled wood.
Also, look at antiques that are still going strong today that are not warped or show other signs of disintegrating due to moisture.
So is the real protection in using properly dried wood to begin with? I think so and a good moisture meter is worth it's weight in gold for those projects that you want to be heirlooms.
On the other hand, using a "balance sheet" or other means to keep the wood moisture content equalized for a long period of time makes sense. Especially for those objects subject to extreme environmental changes, like outdoor stuff - right? So why don't we coat the underside of our wood decks or paint both sides of the wood siding use on homes and for trim?
Buy double the amount you need, sure. Economical, not so much. Grabbing another 'left-over' from a different batch CAN create an imbalance. BTDT. Proper balance sheet eliminates that and *is* spec on many commercial applications. 'Balance sheet' is inexpensive, does the job, meets spec. You can use Balance sheet opposite GP grade or post-form grade. Try to put some GP on top and post-form laminate on the bottom and watch what happens. Again, BTDT. Also, when seaming, make sure the seams are aligned top to bottom.
Laminate's a problem because the stuff is strong in tension and any change in strain (moisture etc) can cause a stress to be set up. If it's a laminate with varying properties between layers, this differential stress can lead to warping, as one layer pulls on the other. For Formica it's usually because the timber moves, but the surface decorative laminate doesn't.
Marquetry has no tensile strength. If there's movement, this will be absorbed by the joints opening up before anything warps. There's even some evidence that the early use of inlaid bandings in early large veneered casework (tables, desks, bureau tops) was for just this reason, not just for decorative purposes. It acts like an expansion joint in a concrete road.
So how much marquetry uses laminate (where, in this context, as anyone with a tenth of a brain would have figured out, "laminate" means "decorative laminated plastic", the plastic stuff that is sold for use on kitchen counters and the like, and not strips of wood stuck together with glue).
I was under the impression that the issue was that the laminate was more or less impervious to moisture, so a change in humidity caused the unlaminated side to expand or contract while the moisture content of the laminated side remained unchanged. Have I been misinformed?
v. lam=B7i=B7nat=B7ed, lam=B7i=B7nat=B7ing, lam=B7i=B7nates v.tr.
To beat or compress into a thin plate or sheet.
To divide into thin layers.
To make by uniting several layers.
To cover with thin sheets. v.intr. To split into thin layers or sheets. adj. (-nt, -nt) Consisting of, arranged in, or covered with laminae. n. (-nt, -nt) A laminated product, such as plywood.
Now... YOU have decided that we're talking exclusively, by Clarke's decree, about "decorative laminated plastic", agin, twisting and bending the conversation so it suits YOU.
'Balance Sheet' is not "decorative laminated plastic", in fact, it isn't even close to decorative, nor is it 'plastic'... it is paper/ phenolic. Now I KNOW where you're going to go with the word 'plastic, that it, in fact means:
Capable of being shaped or formed: plastic material such as clay. See Synonyms at malleable.
Now, seeing as we are exposing all your f*ck-ups from now on (yes, you ARE my new hobby) Asperger defines as follows: Asperger syndrome is distinguished by a pattern of symptoms rather than a single symptom. It is characterized by qualitative impairment in social interaction, by stereotyped and restricted patterns of activities and interests, >>>>>and by no clinically significant delay in cognitive development or general delay in language.
Those countertops don't have moisture exposure on top because of the laminate, nor on the bottom which is 'inside' the cabinet, away from airflow. They're also weak and multiply-supported underneath.
I suspect the rail/stile/panel construction of yesteryear works with green panels, and if the joinery is good, holds the rails and stiles straight even if THEY were green before assembly. The only need for 'balance' sheets is on large sheet goods (plywood) which is relatively recent as a furniture-grade product.
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