Paul Jacobson
7/2/2025 3:03 PM
Bill,
Probably the hardest ( toughest) clear finish is an oil based polyurethane designed for floors. Varathane’s oil based product has been the benchmark for this for decades. Minwax makes a competing product and Varathane also makes a waterborne version.
There may be two-part polyurethanes, such as used in automotive finishes, and similar products used in coating bowling alleys which are equally tough, or even stronger. Certainly a finish which can take pounding by hailstones and bowling balls is going to exceed the requirements of a dining room table. But some of these may not be sold to small firms or individuals for safety or insurance reasons, or may sold strictly to commercial firms in large quantities.
Some states do not allow the sale of the oil-based polyurethanes, due to the high volatile organic solvent content, and resulting health concerns. Indiana does have that prohibition.
But definitely use a respirator mask with the proper filter for organic solvents—and work with a lot of ventilation— if you use an oil based polyurethane. After the solvents are gone the stuff is perfectly safe.
The water borne versions are definitely much safer to work with, and the difference in strength is negligible.
Interior ( not floor grade) polyurethane is the usual table finish. Again, there are water and oil versions.
Unless the table will be kept outside, avoid exterior ( spar) urethanes. These are softer. They are designed to stretch a bit under heat, sun, and changes in moisture, where a harder finish would crack.
You say these tables are being made from recycled fencing. That may be a concern.
Is it cedar? The common material is Western Red Cedar.
If so, the wood itself is pretty soft, and can be easily dented. A polyurethane finish will not toughen the underlying wood. A really hard finish will possibly crack if subjected to a shock that compresses to wood underneath it.
There is a way to solve that issue: fiberglass. This technique is expensive, and time consuming, but adds great strength and a beautiful deep clear finish. It is a common practice used by builders of small boats (canoes, kayaks, racing shells, etc) for over 50 years and there are numerous books and articles on it.
Essentially a clear polyester or epoxy resin is coated on the wood surface, and while wet, a layer of woven fiberglass cloth is placed on top, and saturated by additional resin. Squeegees or foam rollers are used to ensure the fabric is embedded on the resin, air bubbles are forced out, once gelled a second or third coat is resin is applied, then, after several days of curing it is sanded flat and covered in a clear varnish. Often a polyurethane based product. The glass fabric becomes transparent and the thick layers of resin and glass look like a very thick varnish finish.
Probably a lot more work than needed for a simple tabletop.
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Last kitchen table top I finished was last year, for a neighbor. I used Minwax glossy spray on polyurethane in a rattle can. About as simple as could be. Not the floor polyurethane. No fiberglass or anything special. Three coats. Light sanding between coats 2 and 3 with 220 grit sandpaper. Very little clean up.
I ate off of it last week at a party there, and it looks like new so far.
Paul Jacobson
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