Michael Dresdner » finish repair

Spot on

Michael — Thu, 02 Dec 2010 14:00:52 +0000

Q: Can no-sand floor renewal finish systems fill in worn spots on a baked on factory finish?
A: Yes, they are made to go over any finish. However, the problem with worn spots is that they may or may not look the same. Many, but not all, finishes, both commercial and industrial, add amber to the wood. The refinishing kits are typically waterbased and do not add any color to wood. Thus, the bare spots may come out a slightly different color than those areas with original finish. It all depends on whether the original finish was slightly amber or water clear.

Wax on, wax off

Michael — Thu, 25 Nov 2010 14:00:18 +0000

Q: I have waxed oak floors. They are extremely dull. I used liquid cleaner with dark pigment but that only seems to last a few weeks before they dull up. Is there a better product?
A: Commercial cleaners remove wax. Thus, if the shine from your floors comes from wax, using a wax removing cleaner on it will indeed dull it. The way to rejuvenate waxed floors is simply to wax them again. A good application of paste wax will add back what wax was removed during cleaning, and buffing the wax will bring up some shine. When it gets dull again, wax and buff again.

Unstaining

Michael — Mon, 01 Nov 2010 14:00:25 +0000

Q: My stepson recently purchased stain from the cabinet supplier of his kitchen. The plan was to match the color to his unfinished crown molding. The color is wrong. Since the molding has contours, it can’t be easily sanded off. Is there a solution for stripping down to bare wood?
A: Most stains can be scrubbed at least part way off with lacquer thinner on nylon abrasive pads. It won’t remove all the stain, but you may get enough off that you can restain with something that adjusts for the problems while bringing you up to the color you want. That can be done either with a second stain operation on raw wood, or with a toner, which is stain mixed in coating. Either way you will need to mix a custom color stain to compensate for what you could not remove, and add whatever colors are missing from what you want to end up with. This is not necessarily a job for a neophyte as it does take some skill with color matching and compensating.

Unwanted stains

Michael — Wed, 27 Oct 2010 14:00:09 +0000

Q: I just bent some cherry sides for an acoustic guitar. A reaction must have occurred during the bending process resulting in green blue spots on the wood surface. What do you recommend to eliminate or minimize?
A: Removing stains depends first on know what caused them. Blue green stain is most likely one of three sources: coming in contact with natural or artificial stain, such as extractives from a different wood bent in that press; a reaction with a metal surface; or blue green mold. Sadly, each has a different fix.
Contact with a natural or synthetic dye will usually come out with a wash of laundry bleach. That will not change the color of cherry substantially. Contact with a natural pigment is usually only on the surface, and will sand out fairly quickly. A reaction with a metal can usually be reversed with a wash of a ten percent solution of oxalic acid, and that won’t harm the color of cherry either. If it is blue green mold, about the only thing I know of that removes it is a wash with a fairly concentrated (30% or higher) peroxide solution, and that will substantially darken cherry.
Do some detective work first to figure out the likely source and the fix should be easier.

Kitchen magic

Michael — Thu, 16 Sep 2010 14:00:38 +0000

Q: The kitchen cabinets in my 20 year old house were painted rather than stained. They are a cherry color on what I believe is alder. Over the years some of the paint has chipped away leaving behind part of the original unfinished wood. The cherry paint itself is not a solid color, but varies in color a bit. Can a handy person do a decent patch up job?
A: Absolutely, but it helps to know what you are dealing with, and it’s not paint. It’s called toner, which is clear finish with some color added to it, though not as much color as would be in an opaque paint. Instead of staining the wood, the wood is sealed, then sprayed with layers of semi-transparent color until one gets a uniform tint. Spraying more means darker, more opaque color; less gives lighter, more translucent color.
Because that is such a common method of coloring cabinets and furniture, there are common repair materials available to do touch up. They come in two distinct types; pens and aerosol cans. Touch up pens are essentially felt tip markers made in common furniture finish colors. You use them just as you would a marker, simply coloring in the light areas to match. You can also find aerosol cans of toner or tinting lacquer which you spray on the area to blend in the color. Both are quite easy to use. Just make certain you clean the area, or better yet, the entire cabinet, with a good degreaser first to ensure good adhesion. The cheapest effective cleaner is mineral spirits, also sold under the name paint thinner.

Reversing time

Michael — Fri, 03 Sep 2010 14:00:41 +0000

Q: I’ve looking at a restoration issue in some of the old Chicago bungalows where what I assume is varnish has almost coagulated on the surface of the wood trim. On most of the woodwork it’s acquired a nice patina and I’m trying to figure out how we could smooth the surface without removing the patina.
A: That depends largely on what you are defining as patina. That term, borrowed from the metal industry, actually refers to a specific kind of oxidation, but people in the wood industry use it to mean a variety of things, from the change in the color of wood itself beneath a clear finish, to changes in the finish atop the wood, and various combinations of the two.
If you mean the former, you can chemically strip wood without sanding it, and thus without altering the sun fading or darkening that occurs through a clear finish. On the other hand, if you are referring to anything in the finish itself, almost all finish aging, from clarity to color to sheen, can be copied. That’s the finishing part of the art of antique reproduction.
Some older finishes, notably shellac and similar natural resin spirit finishes, will form coarse globs of finish on what was once a smooth surface. Many of these can be dissolved and redistributed with a material called amalgamator. That’s tricky stuff to use, and if you have not used it before, I would not try it out on something that matters. The idea is that you can keep the original finish itself, with the wood color and even finish discoloration still intact, and simply reflow it.

A shade more glycerin

Michael — Thu, 12 Aug 2010 14:00:01 +0000

Q: I just obtained two small table lamps made of burl and the lampshades are of what appears to be birdseye maple veneer. The veneer is fabric backed and very brittle. As a result there are some small voids and cracks in each shade. I plan to back the voids with wood putty and then use a wood stain. This won’t entirely correct the problem but do you have any suggestions for application? Moreover will glycerin help to restore some of the suppleness and help avoid future cracks?
A: Glycerin may help restore some suppleness, and may even help slow the cracking, but once you put it on, you really can’t do anything else. In other words, glycerin will prevent the stain you plan on using from taking evenly, and stain will prevent the glycerin from being absorbed. You may have to choose one or the other.
To be honest, I don’t understand why you want to stain the shade veneers, but if you do, you’ll have to clean and sand them first. Most household goods develop of thin coating of airborne oils, and while they look clean, are not. Raw wood will simply absorb such oils. Either way, trying to stain other than raw, clean, sanded wood can result in problems.
For what it is worth, the cracking is almost certainly a function of the heat and attendant dryness coming from the bulb behind the lamp shade. Replacing the bulbs with cool to the touch compact fluorescent bulbs will help eliminate much of the heat and may prolong the life of the shade.

You make me blush

Michael — Wed, 11 Aug 2010 14:00:51 +0000

Q: My painter sprayed lacquer recently on a hot and humid day and trapped moisture under the finish. Having had experience with this I told him to re-spray with lacquer retarder added to the lacquer and to remove the humidity from the room before re-spraying. This worked to a certain extent but still did not get all the moisture out. Should we just add more retarder to the mix and re-spray?
A: Yes, exactly. Or, in extreme cases, simply spray pure retarder thinner which is available in convenient aerosol cans or in liquid form as “blush chaser.” If you go that route, be careful; you are spraying pure thinner, and if you get the finish too wet it could run.

Pumice problems

Michael — Wed, 16 Jun 2010 14:00:52 +0000

Q: When using pumice stone and linseed oil to rub out slight discoloration in an inlaid dining table I encounter little spots forming. The discolorations do disappear.
A: First, if you must use pumice (and there are far better alternatives), pair it with a non-drying oil such as mineral oil, not linseed oil. As for the spots, if they are tiny and in the wood pores, it simply means you are packing pumice into them. You can remove it by scrubbing with a soft bristle brush and wiping.

Polyester problems

Michael — Wed, 02 Jun 2010 14:00:06 +0000

Q: Short of sanding it off, is there any way to remove a polyester finish from guitar sides?
A: Yes, but it might be faster and easier to sand or scrape it off. For guitars with solid sides, you can make the job easier by working it off with a heat gun. When heated, polyester tends to separate from the wood and you can sometimes get a thin spatula behind it and zipper off large sections. As for chemically removing it, that too is possible, but slow. Use a boosted DCM remover, usually called “marine stripper.” In addition to DCM (methylene chloride) as the active ingredient, these strippers often have either acids or bases added to make the stripper “hotter.” Nevertheless, you will have to daub it on liberally, then cover it with plastic sheeting to keep it from evaporating, and give it a good long time, from hours to a day or more, for the stripper to do its work. It will eventually get it off, but as I say, it might be quicker to work with a heat gun, putty knife, scraper and eventually sandpaper for what remains. By the way, the chemical stripper will also dissolve the plastic binding; another good reason to get physical instead of chemical.