I've just applied the sixth coat of semi-gloss and the piece is looking goo d. IIRC, the last time I used poly (maybe 15 years ago), I did a light pas s with 0000 steel wood after the final coat just to smooth out the surface. Oui? And I have a nice can of Johnson paste wax. I'm thinking about a c oat of Johnson after giving the poly a week to cure. Thoughts?
Larry
If this is oil base poly varnish, a week is insufficient. Wait at least two weeks, preferably four. If/when you use the steel wool, use it sufficiently to make a uniform looking surface - which is way more than a light pass - then wax.
BTW, 6 coats is overkill. I only use four - sometimes three - on surfaces that receive heavy wear (like floors).
The nice thing about the steel wool is it will give you the sheen you are looking for. It will knock down that plastic look somewhat. One of the reasons I don't like poly, it looks like plastic. You can again use wet dry in 600 and above to get the sheen, and finish with steel wool, or just do it in steel wool. Again use a lube.. like mineral oil.
The paste wax won't offer protection above the poly, but it might give it the glow and feel that you are looking for. You can remove it with mineral spirits if you don't like it.
You might as well apply the wax with the steep wool, save a step.
It may be dry after 24 hours but "dry" and "cured" are two different things. Heck, his semi-gloss is still going to be nearly as shiny as glossy for at least 10 days.
If one sands a finish too early, one is removing more or less equal amounts from both hills and valleys, "hills and valleys" being the minute differences in the wood's surface. As the finish continues curing, it continues to shrink...what was once smooth and flat no longer is. IME.
I agree. Curing takes longer. Mike you know how paint balls up when it hasn't gassed off for a few weeks. Same with poly. It's better after a week or 2...
Poly does not have to look like plastic, but it takes a little time.
Three to four coats of polu Let cure three weeks Wet sand with 400 Rub with pumice Rub with rottenstone Wax
It will have a nice sheen and look very high quality.
As usual, a spirited discussion with little consensus. I ended up with six or seven coats (I seem to have lost count). I am very satisfied with the look, but it is a tad rough to the touch. I'm going to wait a couple days and then use a light application of 0000 steel wool, just to get back to ba by-butt smoothness.
Larry
I've just applied the sixth coat of semi-gloss and the piece is looking good. IIRC, the last time I used poly (maybe 15 years ago), I did a light pass with 0000 steel wood after the final coat just to smooth out the surface. Oui? And I have a nice can of Johnson paste wax. I'm thinking about a coat of Johnson after giving the poly a week to cure. Thoughts?
---------------------------------------------- SFWIW, I wait a minimum of 30 days before starting a "rub out"
Like chicken soup, no medicinal value but it hadn't ought to hurt.
Lew
Hmmmm....
Lots of good and bad information here. I do this for a living, but as alwa ys, your mileage may vary. Just some random thoughts:
Good post DadiOh. Dr. Marlow, don't confuse that high powered ultra hot sp ecialized poly you shoot with the big box stuff going on a home project app lied with a paint brush. With your experience and skill level in auto pain ting (a highly technical field when done right) you might be thinking the o ff the shelf products the average guy uses perform as well as your stuff. For example, I sometimes shoot a pre catalysed polyurethane conversion lacq uer that you can recoat in 20 minutes and get full adhesion, no sagging and no witness lines! Try that with Minwax, Bartlett's, General Finishes, ML Cambell, etc.
So, here's my take. To anyone reading this, remember what you paid for it.
I don't sand between coat of poly unless it is to remove a nib or drip. NE VER. If you recoat when you should, you don't need to. I have never had a finish fail. Sand if you need to, but it isn't required. I have sanded be tween coats and it has caused me more heartburn that it is worth. Practice your application, learn your product carefully and you won't have to do it .
Using soap to sand between applied coats of anything but more soap is folly . Why would anyone use a surfactant product that is loaded with perfumes, dyes, oils, silicone and other chemicals to sand? This is an enormously ea sy way to foul your finishes. If you must sand, buy non-stearated paper to use. Steel wool has oils in it, and even the ones that don't will tend to break off the fibers (as designed) and leave them behind on your finish. If you cannot find non-stearated paper, find the very finest Scotch Brite p ad you can get (white?) and use that.
You don't need more than three coats of poly. Each coat should be applied at a uniform 3 mil thickness, which will dry to a thickness of about 1 mil. (This is based on a precat product with 25 to 30% solids). Three coats w ill give you a final build of 3 mil, which is great for most tables, furnit ure, etc.
Wear resistance is not based on final product thickness. Additional coats c an make the final product discolor more easily, and since it is not applied as designed, in come cases make it unstable or brittle. Wear resistance i s based on proper application as specified by the manufacturer that designe d the product, and the quality of the resins used in its manufacture.
I have not put on a poly finish in years (remember Mike... not your stuff) that doesn't require 21 days as the magic number for full cure. Yes, green cure is in as little as 48 hours, but full strength isn't for much longer than that.
The longer the finish has to cure, the harder it will be as all chemical an d physical actions/reactions will have ended. The harder the finish is, th e easier it is to "rub out".
Putting wax on polyurethane is silly unless it makes you feel better. A pol yurethane is nothing more than a modified plastic polymer, so you are waxin g plastic. Certainly the wax provides NO value to the protection of the wo od. Waxing can lead to build up of wax residue, and improper application ( say at the wrong time) can foul your finish.
As a finish dries/cures, it shrinks. It will flatten on its own, without a ny fuss. This is easy to see; how do you think your brush marks disappear? Why do you think your lap marks reduce or disappear? The last Minwax app lication I did for a table top I applied with a lamb's wool applicator and every single ridge and valley disappeared. All of them. You can also see this when you put poly on an unfilled wood like oak, or fill a rough spot i n a board. You fill them when you apply, then come back later and the prod uct that filled the holes in the oak and shrunk back, the tension is broken and the holes in the oak are readily seen. Filling a board with planer ch ip out around a knot will look good until the product dries, then you will see the chip out very easily. This is why you pore fill, and fill divots. The product shrinks and tightens up. It does not sag or relax to fill imp erfections.
As pointed out by Ed P, you can get an incredible finish that would make an y furniture maker proud using poly if you are willing to put the work into it. For years, Jeff Jewitt had a great picture on his web site of his bran d of poly (Target)sitting on a table. He did as Ed described, and the refl ection on the table that used his poly and that method made a mirror like f inish that reflected the poly can perfectly. Really nice. It could easily be confused with a rubbed lacquer finish.
There is a lot of great information out there that can be easily had. Here is a great primer on polurethane:
Use articles from credible finishers as your guidelines and do what works f or you after you try out their advice and tips. By the way, Bob Flexnor wr ote the above referenced article; if he says it, you have a 99% chance of b eing able to take it to the bank. My finishing got noticeably better after I read absolutely everything I could find that he wrote. The man is a mast er of PRACTICAL finishing techniques.
Mr. Marlow and I have talked about this aspect, too. It is soooo easy to c all the manufacturer of a product and ask them any questions you have. Why rely on a bunch of guys you don't know? You might be getting advice from a guy that applies finish to a project every six months or longer, and uses product that is a couple of years old. That won't yield anything good. E very can has a tech support number these days and usually a tech guy on the ready. I call whenever I have a question about anything to do with their products and the manufacturers have always been glad that someone took the time to call them before starting their application as opposed to calling a fter they screw it up.
Good luck. Remember, practice on your scraps, not on your projects.
Robert
Nothing is wrong, just not cured. I just did one of my floors...three coats semi-gloss, took two weeks for the shine to settle down. _________________
He wasn't asking about scuffing. _______________________
Actually, it is closer to 30 days. __________________
Too soon and you sand the hills down flush with the valleys so all is nice and even but the valleys have more finish, the finish there continues to cure/shrink and you are back to hills and valleys. That is what I have observed over the last 50 years or so. The same is true of any finish, glue joints too.
-------------------------------------------------------- I'm reminded of the ad campaign of a northwest brewery that didn't have a lot of distribution outside of the NW.
When customers threatened to come to NW to get the beer the brewery took out an ad.
Just send the money, we'll send the beer.
Lew
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