SV: [CR]Linseed oil and shellac.

(Example: Framebuilders:Chris Pauley)

From: "Olof Stroh" <olof.stroh@hem.utfors.se>
To: <classicrendezvous@bikelist.org>
References: <95.54a4639.278cb26e@aol.com>
Subject: SV: [CR]Linseed oil and shellac.
Date: Tue, 9 Jan 2001 20:33:24 +0100



> << I wonder if shellac wouldn't be a better idea than linseed oil? >>

<< Does it matter whether you use raw or boiled linseed oil? I have two wood/brass levels that I protect with linseed oil but I have yet to find the raw stuff that was recommended. >>

Kenneth, Stephen et al,

Raw linseed oil dries much slower than the boiled. If you don´t put it on _very_thin it will also be sticky inside for forever also if the surface will dry (in which case it will probably have a russin skin surface).

The mechanism behind is that linseed oil doesn´t dry, it hardens together with oxygen from the air. In that process it gets bigger, thus the corrugated skin that also prevents oxygen to reach the inner oil that remains sticky.

Raw linseed oil has smaller molecules than boiled and thus penetrates (the list manager told you to keep silent!) wood easier. The best penetration is at 135 degrees Celsius in which case you have to use a brush with natural swine bristles (and always throw away used cloths afterwards because they lit by themselves when they dry - so be careful _where_ you throw them).

But I digress.

This stickiness is valuable because a dry, hard linseed lacquer may get cracks that are a starting point for rust, still more so shellac which is one reason why linseed oil is better. The oil is also more hydrofob than shellac.

Olof "did I told you that the hot linseed oil will burst into flames in the kithen when just a little hotter"Stroh Uppsala Sweden