Black Pipe and Pipe Clamps from WoodCentral
If you've been woodworking for a while, you've likely heard -- or uttered -- complaints about stains from black pipes getting onto your wood (and other stuff).- Editor
is it that black pipe, which rubs off on everything unless it is sanded and cleaned, is used rather than galvanized [pipe] in [pipe] clamps? - Brad K.
A theory as to "why." - Editor
"It has been said that galvanized pipe will slip more in the clutches of the clamps. Not knowing any better some 35 years ago, my first pipe I purchased was galvanized. I can't tell any difference. Black pipe was/is cheaper, so most of my pipe clamps are black pipe."- Dale L.
Some suggestions for getting rid of the black stains. - Editor
"Use oxalic acid (e.g., Barkeeper's Friend) to remove the black stain. I cut several short lengths of PVC pipe, and slide them over the black pipe, to use as standoffs. They're easier to find than the wax paper or Visqueen [polyethylene plastic sheeting], if I leave them on the clamps. The only problem I have with them is having to take off the extras if I need to use a long clamp on a narrow glue-up. You'll find out if you have too many during the practice dry assembly." - William D.
"All of my woodworking career, folks have complained about the black-bluish stain on wood with tannic acid, oak being the worst. Yes, I get the stain, but a few swipes with a plane removes them, never has been a major problem for me." - Dale L.
"I use both. Never noticed a difference except one thing. Black pipe+white/yellow glue+oak= black stains. I either use tape or waxed paper between the pipe and the wood when using these together.The water in the glue reacts with the iron in the pipe and leaves a black stain on the oak. For this reason only, I wish all my pipe clamps had galvy pipe." - Jack G.
"I have found if you sand and sand and sand the black pipe one can remove almost all the black from staining your hands and the stock, but not all. So wear gloves already!" - Brad
Some suggestions for workarounds involving replacing or covering up black pipe with PVC. - Editor
"This is going to be a stupid question, but how do you put the PVC on the pipe? By taking the end off?" - Larry<
"Well, you can take either end off. One end screws off, but that one is the more difficult, unless you have the thread protector end cap on the other end. It's difficult to get a grip on the cap, and you have to unthread it. I don't use the end caps, so I find it easy enough to push on one end of the gripping plates (whatever you call them) to slide the sliding end off. Putting it back on easily only requires that you push on both ends of aforementioned stack of plates." - William D.
"I've started putting the black pipe on the top over a couple thin wood strips, thereby holding the pipe above the surface and Bessey's or black pipe underneath where the staining doesn't matter. A benefit is that I don't get the bowing upward as with the clamps all on the bottom. Now that I've used the galvy and find them acceptable, I will phase out the black pipe." - Brad
And a question about why people use pipe clamps at all -- plus some answers. - Editor
"For some reason, we all seem to begin with pipe clamps. Once you use a handy bar clamp the pipe clamps are never used again. So take heed and skip over the pipe clamp step and buy bar clamps to begin with." - Bill T.
"I agree, but when I got my first set, I wasn't aware of an alternative. Since then, I have bought more when other people get better clamps. They go real cheap at yard sales and flea markets, and you can never have too many clamps." - Jack G.
"I bought a milk crate full (17) at a garage sale for $15. I cleaned them up and repainted all of them. I made a deal with a friend who owns a machine shop for the pipe. He had a whole bunch of old black pipe, so I used his horizontal band saw to cut the pipe, and his pipe threader to thread the pipe. I traded him 7 of the clamps for the pipe for my 10 clamps. Now I have 10 pipe clamps, plus a few extra pieces of long (6 ft.) pipe for a total cost of $20.74 ($15 for the pipe, & $5.74 for a can of paint), plus a few hours of my labor. At $2.07 each out of pocket ,that is why I am using pipe clamps." -
"Because I've never seen a 9' long bar clamp." - Robin C.
"Pipe clamps are a necessity in a custom shop! Take them to a pipe fabricator and have them roll the pipe into a curve. Works great for radius panel glue-ups. I've even made them up to 16' long with couplings." - Dick C.
Spray Painting Help from WoodCentral
The poster who began this thread was new to spraying, was attempting to spray polyurethane -- and was running into difficulties. - Editor
"I recently bought an HVLP sprayer and am having a problem. Everyone said that I should be able to spray polyurethane out of the can. I checked the viscosity at 10-12 seconds. However, there was no info about how to adjust the spray. After my first spray, I had a very uneven finish; there were large drops of spray interspersed with very fine spay droplets. In my second attempt, I adjusted the spray so it went from nothing to what appeared to be a full spray, which was about one or two full turns on the adjustment, much restricted from my first attempt. The problem is I am not using a colored paint and, as such, cannot see the result even on a sample piece. Does anyone have suggestions about how to set the spray up? I do not plan to spray again until I get some advice." - John P.
Thinning the substance was one suggestion. - Editor
"It is too thick to spray with conventional gun. I thin it 1 part mineral spirits or naptha to 3 parts varnish (approximately). Only brief experience with HVLP gun, didn't like it and returned to conventional which is easier to use."- Bill T.
Others suggested using better light, spraying vertically, and using water as a "test" spray. - Editor
"If you are having trouble seeing how the spray pattern is going on the work, you need more light, and more light, and more light. Put the work between you and the light, so when the liquid goes on, the light reflects into it. Sometimes you have to rotate yourself around, so the light is constantly reflected on the wet finish. Poly is next to impossible to spray. If you can get it thin enough to go through your gun, it will run off horizontal work like crazy. It's not the thinning that will get you, it will run on stuff right out of the can too. It flashes off so slowly, it just runs off the work if you get just a tiny bit too much on the work. Flat spraying only if you want it to work." - Dick C.
"If you are laying on such a heavy coat that you need to have the surfacehorizontal, you are spraying too heavy a coat. I spray enamel paint and varnish regularly and have no problem doing so. Pick a hot day so it will dry dust-free quickly. But the good lighting is essential. If you are new to spraying, practice on a piece of cardboard spraying water. When you can get an even coat of water without runs you will be ready to move to varnish or paint. I find it harder to spray a horizontal surface. For something like a drawer I will spray vertical then move to horizontal for drying." Bill T.
"Spraying with water is a good idea because you can set the spray pattern and judge ideal distance coming off the gun, too. Remember, though, that once you get the hang with water, the viscosity of the final finish will probably change from water. There will be experimentation required there, too, but you should be able to control the gun much better." - Gary S.
The original poster reported back on what suggestions he had tried -- and what worked! - Editor
"Well, after spraying on cardboard with water, I used the 15-10 percent dilution suggestion for the poly and tried it on cardboard also. By this time, I had anchored the work to prevent it from rotating. All went well. I even sprayed my cherry desktop which I had spared from all the failure attempts. All went well. Now for a second coat in my garage tomorrow while the bugs and the weather cooperate. I am no master, but your tips have moved me forward from being a klutz. Thanks so much for the help. This is the first time that I have sprayed anything." - John P.