>Just tried my first shot at "wet sanding", i.e., I
put a pretty good amount of Watco on a piece of dry cottonwood, let it soak in and hit it with power disks up to 320, came out very nice without the dust. I just got a can of Deft and with it came some info about finishing in which it said to apply it then wipe, let dry, buff then apply "polymerizing oil" to 0000 steel wool and apply that while still on the lathe. Is Watco a polymerizing oil? I guess what I'm asking is what is polymerizing oil? Tung oil says not to use over other finishes. I don't want to loose this bowl if I can help it.
>I cannot comment on the tung or watco, but I do know that Polyurethane (sp) is a polymerizing oil finish. Apply it the bowl, and then buff with a soft cloth while the lathe is running, the heat from friction will polimerize it. Makes a nice shiny, dust free finish in minutes.
>The short answer is they are recommending any commercial finishing product, but not Mineral Oil.
"Polymerizing" is any oil that will "cure", or change state, to form a finish on a piece of wood. We usually call them "drying oils" because they will become "dry" to the touch. Tung Oil, and Walnut Oil are natural "drying" oils. Others such as Sunflower Oil and Raw Linseed will also "dry", but only if you are willing to wait a long time (days to weeks).
"Non-drying" oils are those that will never do anything but stay the way they are. Mineral Oil, motor oil, lubricating oil, animal fats, most vegetable, and all cooking oils are "Non-drying".
Just to make it complicated, some of these "non-drying" vegetable oils can be modified with the addition of "drying agents", so that they can be used as a finish. The two most common of these are Linseed and Soybean oils, neither of which would be considered as a finishing product without their being "modified" or having "drying agents" added to them. With the addition of these "dryers" they become the basis for almost every finishing product on the market. The Watco oils are a "modified" Soybean oil, as are many other finishing products. Several of the Minwax finishes use Boiled Linseed Oil (BLO).
Just remember that the manufacturers have figured out a lot of ways to market what is essentially Linseed or Soybean oil and thinner. There is very little difference in any of these products. So pick the one you like and use it. If that is Watco, there is nothing wrong with using that.
Beware of labels that say "Tung Oil" finish. That has become a generic labeling and most of them that you see on the store shelves have nothing that is associated with Tung Oil in their ingredients. Waterlox and Gillespie's are the only nationaly distributed finishing products that really contain Tung Oil.
As for using Tung Oil or Boiled Linseed Oil over a lacquer (Deft), there is nothing wrong with doing that. It doesn't matter whether the lacquer is wet or dry, they are compatible.
Thanks for the concise info on "polymerizing oils". I went with Watco and ended up with a rather "soft" effect on the cottonwood bowl which is very pleasing.