Wood – Does pickling wood with steel wool and vinegar harm the wood

There are 2 basic categories for wood finishes; those that penetrate, and those that coat. Linseed oil, wax, "hand rubbed polish" finishes are all examples of a penetrating finish. Varnish, lacquer, shellac are examples of coating finishes. There are many different reasons to choose one over the other. Some factors:

• what type of wood
• how will the wood be used
• tools available
• skill level

In general, penetrating finishes are the easiest to apply, and the most forgiving of mistakes and easiest to repair. But they offer minimal protection against the elements, scratches, etc. Also they don't look best on soft woods, i.e. pine, fir, etc.

The coating finishes are really a progression of technologies. Shellac was the original hard coat finish, but has been replaced for the most part by lacquer and varnish. Lacquer is generally used commercially as it dries fast and can be re-coated in minimal time. Varnish is easier to apply by the average person with a brush. The downside is it takes longer to dry, and therefore more opportunity to catch dust, bugs, etc. Some of the newer water-based "varnishes", however, dry pretty quick.

You have to cut the wood somehow... You can give your blades a wipedown with a slightly damp rag to remove sawdust particles (let them air-dry well afterward), but I wouldn't worry too much.

Corrosion involving PT lumber is mostly a problem with long-term contact; the copper compounds in the chemical treatment are more "galvanically noble" than many common metals including carbon steel, and so an electrochemical reaction will result in the less noble metal (here the steel or iron) oxidizing. The same happens with ordinary zinc-coated or uncoated iron or steel fasteners in PT construction. To prevent this, stainless steel alloys (containing low carbon and higher concentrations of even nobler metals like chrome and nickel) or hot-dip galvanized fasteners (which cover the steel with a thick protective coating of zinc oxide which shields the fastener against further corrosion), are recommended for long-term contact with pressure-treated wood (on the scale of years).

However, your carbon-steel/carbide saw blade will only be in contact with the wood and its chemicals for some seconds. Your saw blades will dull naturally through age and use before the chemicals have any detectable effect.