Planing Phenolic Ply ?

[Doug Shepard]

I need to get a double thickness of 3/4" phenolic ply roughly 4" wide by 36" long. I could screw them together from the bottom where it wont be seen, but gluing them together would be my preference. Any problem with running this through my planer to remove the phenolic layer on the mating faces?

[keith ouellette]

I would sand it. I just recently ran my phenolic router plate through my drum sander to make it more flat.

In your instance I would just used a random orbit sander.

What kind of glue are you using? You may only need to remove the glossy surface.

[Doug Shepard]

Hmmm. I forgot about maybe using my drum sander. That might work out better. I was just going to use Titebond or whatever yellow glue I happen to have here if not TB.

[george wilson]

Phenolic is very hard on tools.I have turned it in a wood lathe.Had to resharpen my chisels frequently. it probably would ruin your knives. It is also very smelly when it is being cut.

I made a steering wheel out of a thick sheet of linen impregnated phenolic,and it was a pain to turn.

[Alan Schaffter]

Time out!!! Phenolic ply in this case is another name for epoxy coated (and partially impregnated ply. Phenolic itself is a broad term that includes epoxies, melamine, etc.

Don't machine it first and don't use wood glue.

Just rough up and carefully clean (use acetone) both surfaces, cover both surfaces thoroughly with a thin coating of epoxy, and clamp the pieces together but not so tight that you get a lot of squeeze out. The resultant bond will be stronger than the wood plies!

[Mike Sandman]

[QUOTE=Time out!!! Phenolic ply in this case is another name for epoxy coated (and partially impregnated ply. Phenolic itself is a broad term that includes epoxies, melamine, etc. [/QUOTE]

Well... with all due respect, that's wrong. In a prior life I ran a factory that used about 1.5 million pounds a year of phenolic and I hold a 1979 patent for one application of this type of resin.Phenolic, melamine and expoy are types of thermosetting plastics -- they harden with heat rather than soften; hence the designation thermosetting. They are made from different chemicals and they have very different strengths and bonding characteristics.

MUCH more important, phenolic is made, in simple terms, by reacting (or "cooking") phenol and formaldehyde to create phenolic resin. Both chemicals are hazardous to your pulmonary health and under certainly conditions they're carcinogenic. If you sand or mill down the surface of phenolic plywood, please use a very good OSHA-compliant respirator -- a gas mask sort of thing, not just a dust mask.

(If you're just cutting some phenolic plywood on a table saw, a good dust mask will probably do well enough, but particles from sanding are a lot smaller.)

[Alan Schaffter]

Well... with all due respect, that's wrong. In a prior life I ran a factory that used about 1.5 million pounds a year of phenolic and I hold a 1979 patent for one application of this type of resin.Phenolic, melamine and expoy are types of thermosetting plastics -- they harden with heat rather than soften; hence the designation thermosetting. They are made from different chemicals and they have very different strengths and bonding characteristics.

MUCH more important, phenolic is made, in simple terms, by reacting (or "cooking") phenol and formaldehyde to create phenolic resin. Both chemicals are hazardous to your pulmonary health and under certainly conditions they're carcinogenic. If you sand or mill down the surface of phenolic plywood, please use a very good OSHA-compliant respirator -- a gas mask sort of thing, not just a dust mask.

(If you're just cutting some phenolic plywood on a table saw, a good dust mask will probably do well enough, but particles from sanding are a lot smaller.)

Whether it is an epoxy which can have a variety of chemical compositions (the most common epoxy resins are produced from a reaction between epichlorohydrin and bisphenol-A), or melamine formaldehyde (melamine), or some other type of aqueous phenol-formaldehyde resin solution with formaldehyde-phenol mol ratio in the range of 1.8 to 2.8, etc., etc., or other thermosetting polymer that cures (polymerizes and crosslinks), doesn't matter to the woodworker. What matters is that the "Phenolic ply" sold by WW stores bonds well using commonly available epoxy, and just needs a little roughing up first.

The phenolic ply being sold by Woodcraft etc. is covered with a VERY thin layer of paper or linen, and likely a thermosetting (exothermic) "phenolic" OR epoxy- without seeing the specs you can't say. It is certainly not the phenolic of old- the hard and brittle Bakelite made with resin and wood flour or the thick blocks of resin saturated linen or paper products cured under pressure and heat and used in the electronics industry, aviation and elsewhere- I used a lot of this stuff for inexpensive torque tube and actuator bearings. It sure smells when machined, but machines fairly well, and bonds well to other structures using epoxy. While repeated , long-term exposure can be dangerous, especially if you injest it in quantity (like Chinese baby formula) or snort a line regularly, the amount of dangerous dust from occasional exposure is not likely to cause harm. A mask is recommended, but I don't recall seeing any EPA warnings on "phenolic ply", Micarta, Formica, or the melamine sold in stores.

[Doug Shepard]

Alan
How rough a grit do you suggest to rough up the surface? And is just going over it by hand with a sanding block enough or should I go a bit more agressive with the ROS? I've got the epoxy (West) so that's not a problem.
Thanks

[Alan Schaffter]

Alan
How rough a grit do you suggest to rough up the surface? And is just going over it by hand with a sanding block enough or should I go a bit more agressive with the ROS? I've got the epoxy (West) so that's not a problem.
Thanks

Just hand/block sand with 150-180 grit to dull the surface and wipe the dust off before gluing. What you are looking for is scratches/micro scratches that provide a good bonding surface for the epoxy. No need to go crazy with a random sander. Remember you are bonding two large surfaces together with little to no forces trying to pull them apart. West System will work just fine. You won't need much of it, just enough wet the surfaces. Epoxy is an excellent adhesive, it just doesn't have strength by itself in volume. That is why it is often used with other materials in a "composite" which greatly increase the strength. A composite exhibits more strength that its individual components- glass fibers and epoxy - fiber glass, similar kevlar composite, others using linen, paper, etc. FYI, Howard Hughes' huge Spruce Goose seaplane was made wood laminates bonded together with both urea-formaldehyde glues and early epoxies!