Planing Painted Lumber

      Machining recovered, previously-used painted wood is an exercise fraught with potential problems. June 28, 2006

I've been asked about the possibility of planing oak lumber that has been painted or creosoted. Will my planer be capable of this without any harmful effects to the knives and head? It is a double-sided planer, with helical insert knives.

Forum Responses
(Solid Wood Machining Forum)
From contributor E:
Not On My Planer.

From contributor W:
Really bad idea. Better idea might be to resaw this first on a bandsaw, slicing 1/32 to 1/16 off each face to eliminate the paint and creosote, then joint and plane. I wouldn't do it without running a metal detector over all four faces first to make certain nothing is hiding under the paint/creosote that would damage the bandsaw blade.

From contributor H:
Painted or creosoted = hidden metal objects and stones. Give the client Grizzly's phone number and have him buy a cheap planer and do it himself.

From the original questioner:
There is no metal in this lumber! Does this change anyone's opinion?

From contributor R:
Do not run lumber with creosote in it through any woodworking machine!

From the original questioner:
It's paint, not creosote. And we're talking about quantities in the 1000's of BF, and an industrial planer, 30/25 HP head motors. This make any difference?

From contributor R:
I have machined paint off of wood through my planer and besides the fear of what's under the paint that I can't see, the paint adds a lot of friction to the feeding process on the table surfaces and eventually will start to leave deposits of paint if you don't keep the tables lubricated well, which will then hold up the piece from feeding. Another problem is that dried paint is very abrasive to cutting tools because of the mineral components in the paint. It will dull your tooling noticeably faster than anything you are used to. It will also leave deposits of paint on the cutting edges, which increases heat buildup on the knives.

From contributor I:
It's your machine, your knives - I say - hit it!

From the original questioner:
My dilemma is that there is apparently a lot of this lumber to be planed. And more to be done on an ongoing basis. And I'm gonna guess that I can charge as much as I want. Thanks for the answers! And if anyone has a magic solution, I'd still like to hear about it.

From contributor B:
If you have carbide knives in your head, it might work. My experience with painted boards is that HSS knives will dull within about 50 lin. ft.

From the original questioner:
Ah, yes! The knives are carbide inserts and arranged in six rows in a helical fashion.

From contributor P:
I ran a small amount of reclaimed attic floor boards for a good client/friend of mine. Enough for a 12 by 12 room. I didn't want to, knowing there would be nails even though whoever pulled them up "looked carefully" for them. So the deal was - buy me a new set of knives, plus sharpen my old, plus my hourly rate. He said fine. It happened, and I probably would say no next time. It is just not worth it. My advice... don't waste your time.

From contributor A:
What will you do with the sawdust waste? The paint will make it unsuitable for animal bedding. Unless you work with a landscape guy who is not very picky, you'll have to figure on taking it to the dump. My experience with orders of this type is that they would gum up the whole flow of the shop for one reason or another and generally not be worth it.

From the original questioner:
We have someone who takes shavings to solidify liquid waste at a landfill, and I think this would be perfect for that.

From contributor U:
How old is this stuff? Old enough that there is lead in the paint? If so, that's hazardous waste - much more money and hassle to dispose of. Not to mention the OSHA type concerns in your shop with the actual milling (appropriate dust containment, air sampling, and so on).

If not, then it's a matter of profitability. So what if you wreck some blades and/or gum up the machine? If you can charge enough (which you implied), you can buy new blades, pay people to clean the planer. Heck, I'd just get a "throwaway" Grizzly planer and price it in. You'd still need carbide blades, so go for one with the spiral head. Those inserts are pretty economical to buy and replace.

From contributor D:
Roll with it. Your planer sounds heavy duty enough to handle it. Besides, it's metal vs. paint/wood, and big deal if you have to sharpen or replace knives. Charge for it - it's how the world works.

From Professor Gene Wenger, Sawing and Drying Forum technical advisor:
If the paint is lead paint, do not do it. For creosote wood, the heat of planing will cause some of these cancer causing chemicals to evaporate. Do not be anywhere near the planer when this happens.

From contributor C:
If you need the work and are willing to take the risk, go for it. You are a little evasive on the type of wood, why was it painted and what was it used for. I can see very few applications for painted lumber that couldn't end up having some type of hidden metal objects. I probably have a similar planer and after several key episodes, we no longer surface used material, period. First episode involved a 1/2" lag bolt on the underside of a board that basically destroyed the bottom head and left a scar in the chrome plated bed you would not believe. Net result, $2500.00 loss. The next was a millwork project using barn wood from a reputable source that "scans" all lumber for metal. We pulled several coffee cans full of metal using a small Lumber Wizard metal detector, and guess what we missed? Plenty, and vowed never again.

From contributor W:
Reading this whole thread has me wondering how the reward could possibly be worth both the risk and the hassle. Lead paint, evaporating carcinogens, waste disposal challenges, cutter wear and gumming, potential machine damage... And no one has yet mentioned the risk of buried metal turning into shrapnel, posing risk of injury. I'm clearly missing something here.

From the original questioner:
There is no creosote (determined belatedly). There are no nails (the recycled product came from parts of the lumber where there is no possibility of nails). There are other parts of the equation: We would be adding value in a couple other areas, milling and drying. I've talked to the farm supply folks, and creosote hasn't been used in this product in many years. There are no lead paint problems. My main concern is how the lumber will go through the machinery, and what effect it will have on the heads and knives. Will probably do a little experimentation.

From contributor U:
If no lead paint and no metal, give it a try. One thing that would help is to raise up your bottom feed rollers so there isn't the friction between the bed.

From contributor Q:
If this lumber is worth it, have you looked into stripping it first? Or even sanding it off with something like 36 grit handheld or wide belt sander? This may sound crazy, but attach it to a floor somehow and get a floor sander.

I guess it just comes down to cost. If you build the cost of new inserts for your planer or find some way to get rid of the paint first and the lumber is worth it, go for it. (I'm always up for a challenge...)

From contributor R:
Assuming everything the questioner has told us is accurate in terms of no nails or creosote, etc., my experience has been that planing the paint off will be a more economical choice than the price of sanding drums for a floor sander or a wide belt sander. They tend to gum up immediately, no matter what the grit or quality of the belt. Maybe someone else has more experience than I do with this. As little of it as I have done, I gave up on it right away for those reasons. Not to mention it takes longer to sand it off in the number of passes it takes.

From contributor S:
In thirty years of planing lumber, my lifetime average is about 65% on the "There is absolutely no hardware in this used wood" statement. Not that people lie 65% of the time, they just don't know, and are expressing their hopes more than knowledge. I have often said "Tell me that part about how 'there is absolutely no hardware' again."

The more expensive the equipment, the more risk involved. It is not only the cost of re-tipping the head, but those 1/2" lag bolts have a way of mangling heads. What is the cost of the downtime you may have, should your head need to be replaced?

I would lean to abrasive planing, 36 grit, one pass each side, with bright inspection lights at the outfeed to spot metal. Also, a good spark detection on the dust collection is mandatory (ever see a cyclone launch?). Then you can plane without catastrophic risk. Go to Vegas if you like to gamble.

From contributor D:
The worst planer knife damage I've seen (and I've hit some big metal) was caused by wood. An ordinary pine knot, to be exact. Absolutely destroyed a knife, mangled it and almost ripped the whole 20" knife out. Fluke, I guess. Nobody saw it coming, because this was new lumber, which can also have hardware in it. Not as likely, but it happens.

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