Hey, first time posting here. I am a newcomer to table making and I am making a small round bar table from some wood i got out of an old warehouse we tore down. I went to Woodcraft and was talking into buying “System Three Mirror Coat Bartop Coating” I looked it up when i got home and obviously was not what I wanted as it will create a completely flat surface. I am looking for something that will provide a little water protection and cut out the risk of any splinters but stil be able to feel the texture and imperfections in the wood. What is the best way to get what I am looking for? Please help a beginner out.
I have attached a picture of what will eventually be a round table top
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I'm assuming that you want to use the surface of the boards as-is, without planing or sanding them flat. If that's the case, l ooks like there's a lot of grime (sorry, "natural aging") on the boards which somewhat limits what you can use as a coating, due to adhesion issues.
You could try the bartop coating, just using a fairly thin layer. You don't have to put on so much that it levels the entire surface. Test on a scrap to see if it works.
Failing that, here's what I'd do:
- clean the boards well, using TSP and a scrub brush. Twice. Let dry thoroughly.
- spray 2 or 3 thin coats of dewaxed shellac, something like a 1.5 lb cut.
- spray or brush 3 to 5 thin coats of polyurethane (water or oil based), making sure each coat is within the recoat window
I'm suggesting spraying the shellac, simply to avoid leaving lap lines. Brushing the poly is fine, as you don't care if it goes on a bit uneven.
The shellac acts as a layer to seal off whatever contamination is left on the wood after cleaning it, and give further finish coats a good surface to which to bond. The poly is then a very durable and tough top coat, suitable for a working piece of furniture. Yet the total thickness of the shellac and poly together is still relatively thin, allowing the underlying texture to telegraph through.
The best water barrier is likely a finish that forms a film on top of the wood. But the film will make the surface feel less like wood. Brushing any finish likely will leave more material in small dips and cracks, partially filling them. A sprayed finish goes on evenly so it will not fill the dips and cracks as quickly as brushing will. I'm not sure there is an ideal finish for your criteria.
This will get some strong responses, but I'd suggest you try some shop mixed danish oil on a sample of the recovered boards - equal parts boiled linseed oil, P&L 38 gloss or similar varnish, and good mineral spirits (not one of the newer formulations with water). Mix well, brush on, re-coat any areas that look dry (the finish is soaking in), then in 5 or 10 minutes scrub the surface as dry as you can with paper towels. I'd apply four coats, allowing 48 hours between coats. Stir the mix regularly as the varnish may settle. After the last coat has dried for 2 or 3 days, test to see if it has enough water resistance for you, and whether it binds the rough areas enough to prevent splinters. It won't have the water resistance of a film finish, but you'll have to see if a wet glass or mug leaves a water mark after an hour.
Without knowing more about this than you provide, my first choice would probably be to apply a coat of dewaxed shellac. Then apply a couple of coat of a good non-poly varnish. Waterlox Original or Behlen Rockhard would be approriate. Both are hard, durable varnishes.
If you want to maintain the patina, use a stiff bristled brush and aggressively brush to remove any loose dirt. Be careful using cleaners like TSP. It may remove some of the patina. Try out any of your plans on what will be the bottom side first. Save the "money" side until you know exactly what are doing.
One thing I strongly suggest is that you coat BOTH sides equally if you want to better ensure that the tabletop stays flat.
Finally, how do you plan to suport the tabletop? Be sure you do not use any type of construction that will create a cross grain situation. The wood is going to want to expand/contract with changes in relative humidity. The support system must not restrict this movement.
I for one hope you will take time to really "use" the wood. Make your table top. I can't really tell if there is any kind of finsh on the wood but if so, do a quick strip of it with a stripper. Otherwise, clean it really well using mineral spirits and a 3M pad (fine). If it down to raw wood with no finish, the color you see when it is wet with the mineral spirits is the color you will have when you apply a clear finsih. I would wipe on 6=8 coats of wipe on non-poly varnish.
I believe that you will get ring marks from wet glasses if you only use the Danish oil kind of application, no matter how many coats you put on. It will provide very little protection long term.
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