Oil varnish or spirit varnish ?

[mandoman4807]

Can someone describe briefly the difference? I understand that oil will take longer to setup. Will spirit hold up as long, and have the same characteristics tonally?


Darrell

[sunburst]

An oil varnish is a "drying oil" with selected gums and resins added to give it the desired characteristics. Tung oil and Lindseed oil are common.
That means it is an oil that will polymerize (molecules link) when exposed to air. This usually requires a drier or catalyst to get the process completed. The resins used can be natural or synthetic.

A spirit varnish is usually shellac disolved in alcohol with gums and resins added to give it the desired characteristics, mostly to control hardness and drying time. The alcohol evaporates and leaves the shellac and resins to harden on the surface.

Oil varnish is generally more scratch resistant and maybe more durable.

Tonewise, the difference between one thin finish and another is minimal, but someone may chime in here with a lot of experience with the two who can give general differences between the tone of the two.

[mandoman4807]

sunburst,

Thanks for your quick reply on the subject.


Darrell

[Chris Baird]

Violin style oil varnishes are more flexible and put less tension on the wood surface than shellac. Shellac will usually begin to craze relatively soon which is probably an indicator that it is not as flexible as oil varnish. Oil varnishes can be more durable than shellac but not necessarily. As has already been stated many times before the term "varnish" is rather ambiguous and could refer to a myriad of materials and processes. If you want specific detials about a particular finish you will have to provide specific details about your intended materials.