Working with Pre-Finished Plywood
A little extra care is needed to prevent scratches, but the convenience can be well worth it. November 11, 2005
I've never used pre-finished birch plywood, or even seen it. How do you work with it without messing up the finish? Does it come with a protective layer on it? With normal ply, you can sand out some defects if you happen to ding it, but I am sure you can't do that with the pre-finished.
You almost have to use a slider or vertical saw to cut it, although if your Powermatic's table is nice and smooth and greased up, you should have few problems using it. You do have to be careful with it. Some scratches could be filled with a wax stick, although the sheen will be gone.
We use this for 90% of our cabinet work. We cut on a Unisaw and a small panelsaw. Mostly, we use pre-finished on one side and, obviously, this is no problem - just keep the good side up. Use a decent plywood or melamine blade (80 teeth). We still use a lot of dados for complicated casework. We have no problems cutting with a 8" x 46 tooth dado set. The amount of two sided pre-finished is pretty small, and you go a little slower and are more careful. I get less blowout on two side pre-finished versus two side melamine.
I actually use the pre-finished maple a lot for interiors. The finish is usually tough enough to resist most scratches from my tablesaw, but you do have to be careful handling it. I have had a couple instances where, at the end of a run, there would be an outside panel with a scratch. I have not been able to hide scratches or dings on an exposed surface to my satisfaction, so I will usually just sand through that one panel and respray it.
We also use the pre-finished maple for all of our interiors. We buy the two-sided because then we can use it for adjustable shelves and both sides are already finished. Also, if your cabinet has a partition, then again, both sides are finished. If the job is out of oak, we skin the visible end panel with a 1/4" piece of oak plywood. When it comes to finishing, on all cabinets that do not have an exposed side, the face frames get finished first and attached later via glue and pocket screws (less cabinets to put into the booth). Any cabinet that has a finished end, the inside of our faceframe is taped off so no stain or lacquer gets on it. I was introduced to this product about four months ago and it really has changed my cabinetmaking. I would recommend it to anyone.
We use the two-sided stuff whenever possible. On euro cases, we stack parts with longest on bottom, working up to smallest, and just mask off the top of stack and finish all in one stack, then assemble. Any creep of finish on the face of panel is wiped off with lacquer thinner before the finish totally sets up. You can also use a cabinet scraper to crisp up stain line on edge. I know other shops use colored vinyl edgebanding with wood grain print so they don't finish edges separate. For interiors, we use a pre-finished edgeband. For face frame cabs, we finish frames separate, then mount so no masking is needed. Huge time saver.
Keep your machine surfaces smooth and waxed and scratches should be minimal to none. A little polish and 4-O steel wool will take care of minor scratches. They make different grades. We use a b-2 maple. They also make a c-3 and a shop grade. I prefer paying the extra to avoid knotty grains and not so flat boards.
I use Nova pre-finished maple plywood for projects that require wood interiors. I used to be concerned about minor scratches that are sometimes already on the material when delivered or caused by my own manufacturing techniques. But I have found that when the cabinet is assembled and installed and there is no direct light to accentuate a scratch, it basically disappears.
I have used pre-finished on many projects with minor blemishes and have never had an issue. I build very high-end projects and would never condone shabby work, however, getting all hung up about minor scratches on parts that are usually hidden from sight and never closely inspected is a good way of losing profit. This extra attention to detail would be better used in highly visible areas such as tight miters in mouldings, multi-step finishes, plumb, level and square installations, etc. I used to spend inordinate amounts of time getting small details perfect, mostly to satisfy my own ego. The client rarely notices or cares that you went to such lengths to get it right.
I build fine kitchen cabinetry, not studio furniture. There is a difference. My product is something that I am very proud of and my clients are usually blown away by the level of quality. So whenever I find myself spending too much time on minor details, I remind myself of my newest three-word phrase, "get over it!" Some details deserve extra attention, some don't.