Wood Finishing: The Devil is in the DetailsI received the following e-mail from Krystal and her husband Russell, and I thought it might be interesting to those who have found themselves facing this challenging finishing issue. Here is Krystal’s entire e-mail as it was sent to me.

“Hi...was very impressed with your articles in CSW on wood finishes...I feel you would be very knowledgeable on telling us what to do with a table we have..we bought the table 2-3 years ago..love the table ..looks real rustic..oak table with lacquer finish...has solid wood top with grooves every 6-7 inches...the finish is not very good ...so I went to a wood finisher in Chico, CA and he sprayed a little Deft finish on it to see if it would be compatible..it is..would you recommend us using this product or would something else be a lot better..I would love to talk to you about it ... our table is 4 ft by 6ft with 2 boards...we did get 1 qt of the brush-on Deft finish.....HELP!!!!!!!! is this what we should do? Look forward to hearing from the pro..who has been there and done it!”

Here is my reply:

The devil is always in the details, as they say. This is doubly true of wood finishing!

I have read your note several times and I must say that it is hard to tell you how to proceed because the great unknown is what is already on the table for a finish. Having said that, what is on there already may or may not react with what you apply over it. That’s where the devil gets involved. And I assume that’s what the guy from Chico was trying to establish.

Deft makes hardware store/handyman-grade products and they also make professional-grade products. The hardware store versions are for the folks who want to do a little project at home. These products come to the marketplace designed so that folks can't mess up too badly yet come away with a finished project that looks pretty good. The professional-grade products, on the other hand, are designed to be shop applied by someone who knows the ins and outs of finishing so that a much more durable finish may be applied. The chemicals involved here become much more water, chemical, and abrasion resistant. Also, almost without exception, they are designed to be applied by some form of spray equipment in a controlled environment.

What are you describing when you say the guy in Chico sprayed a little Deft?

Lacquers have some rather aggressive chemicals in them. They attack the existing finish. By that I mean that they will often rewet the coating they are sprayed over. At that point, some "mingling" occurs. Now, all of a sudden, the two have become one and neither may clearly know its identity or have its originally designed properties. In a worst case scenario, they may not be compatible at all and all hell will break loose...again, the devil is in the details. Or a year or two down the road things may begin to look pretty bad as the finish begins to come off, etc.

Another issue is contamination. Oak has lots of great big pores in its grain. Contaminants such as oils, waxes, and (heaven forbid) silicones get trapped in these nooks and crannies and are also rewetted by the new coat of lacquer. They come out to play with the new layer of finish while it is still wet and create what we call "fisheyes." They look, literally, just like a fish's eye. There may be one or two or there may be thousands of them. The liquid lacquer will be repelled by that contaminant and flows away from it; "piling up" in a circle in an effort to avoid it.

If it were me, I'd start with some good ol' TSP and I would wash your table several times using clean solution and clean rags each time. I'd want to do my best to remove any contaminants on the surface and in the pores. Then, I'd scuff the table with 320 grit paper to give it a good surface to which the next coat may adhere.

Now, at this point, you have a choice of directions to go. You can load it up and take it to the guy in Chico or you can use your brush-on Deft and do it yourself. If you use the brush-on, you are going the route of least resistance. But the finish that you apply will not be very high tech. But it may well do just fine for your use at home. Just follow the directions on the can and away you go! Also know that brush-grade polyurethanes are used to finish gym floors and they are plenty tough for that demanding environment. I’m guessing that that is what you will get from Deft…but not necessarily. Read the can first!

The guy in Chico may be able to put a much more robust finish on for you. However, you are rolling the dice here too! Those contaminants will be much more likely to come out and play with a spray-grade product. You also have the decision to make about water-borne or solvent lacquers. In that decision alone, there is a whole world of coatings technology from low-tech to high-tech!

We will end here for this week. But stay tuned because I will go into the rest of the story next week!

Until next time…spray on!

 

 

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