Spar varnish
From Wikipedia, the free encyclopedia
*Spar varnish* is a wood finishing
<https://en.wikipedia.org/wiki/Wood_finishing> varnish
<https://en.wikipedia.org/wiki/Varnish>.
Spar varnish was originally developed for coating the spars
<https://en.wikipedia.org/wiki/Spar_%28sailing%29> of sailing ships
<https://en.wikipedia.org/wiki/Sailing_ship>. These formed part of the
masts <https://en.wikipedia.org/wiki/Mast_%28sailing%29> and rigging
<https://en.wikipedia.org/wiki/Rigging>, so suffered a hard life in
service. They were flexed by the wind loads
<https://en.wikipedia.org/wiki/Wind_load> they supported, attacked by
sea and bad weather, and also suffered from UV degradation
<https://en.wikipedia.org/wiki/UV_degradation> from long-term exposure
to sunlight <https://en.wikipedia.org/wiki/Sun_exposure>.
The most important condition for such varnishes to resist was the
mechanical flexing. This required a varnish that was flexible and
elastic <https://en.wikipedia.org/wiki/Elastomer>. Without elasticity,
the varnish would soon crack, allowing water to penetrate to the wood
beneath. At the time, varnish production was rudimentary and had only
simple materials with which to work. It pre-dated the development of
modern polymer chemistry
<https://en.wikipedia.org/wiki/Polymer_chemistry>. Spar varnish was a
'short oil' varnish, where a small proportion of a finishing oil
<https://en.wikipedia.org/wiki/Finishing_oil>, universally boiled
linseed oil <https://en.wikipedia.org/wiki/Boiled_linseed_oil>, was
added to a majority proportion of varnish (see Danish oil
<https://en.wikipedia.org/wiki/Danish_oil> for a 'long oil' finish).^[1]
<https://en.wikipedia.org/wiki/Spar_varnish#cite_note-Allen.2C_Long_and_short_oil-1>
This gave flexibility,^[2]
<https://en.wikipedia.org/wiki/Spar_varnish#cite_note-2> even though its
weather resistance was still poor and relatively frequent re-coating was
required.
In modern times, 'spar varnish' has become a genericised term for any
outdoor varnish. Owing to modern varnish materials, their weather
resistance is likely to be good, but the original requirement for
flexibility has largely been forgotten.
On 05/10/2017 05:49 PM, René Sterental wrote:
Hmmm... now in a conundrum... which should I use?
Don't like the idea of the varnish getting slick (and sticky or
running off?) with soggy leather gloves as when riding in the heat or
rain (no plans for that now), wondering how sticky or slippery shellac
may get on the same conditions, but then again, RBW has countless uses
and its what they use again and again...
Perhaps it's just "safer" to go with shellac, especially since the
captain grips will get twined to hold the cable for the barend shifters.
Any last minute strong recommendations? Those like RonMc who suggest
using the varnish, did you first use shellac and found it lacking?
René
On Wed, May 10, 2017 at 9:22 AM Ron Mc <bulldog...@gmail.com
<mailto:bulldog...@gmail.com>> wrote:
spar varnish is harder to keep, because it cures by exposure to
oxygen. To keep it around you need canned inert gas like Bloxygen
to blow over the top.
But it is flexible. It's what they coat bamboo fly rods with, and
think about how a bamboo fly rod flexes.
It's like an oil, very low viscosity, and the first 4 or so coats
are absorbed by the cork. You want a couple of bright coats over
the absorbed layers.
If you squeeze the cork, it doesn't separate - it's not a hard
shell, it becomes a very viscous oil.
Coated cork will become slick if you're wearing soggy leather gloves.
On Wednesday, May 10, 2017 at 8:17:11 AM UTC-5, René wrote:
Wow, I'd never heard of it. Can you explain a bit more why
it's better and what the flexibility you describe means?
René
On Wed, May 10, 2017 at 5:31 AM Jon Dukeman,central Colorado
<row.n.2...@gmail.com> wrote:
I agree with RonMc..
Spar varnish is better than shellac on cork. This is
clear,gloss, 5 coats, I didn't sand in between
coats.Available in semigloss and amber.
Jon
|
|
On Wednesday, May 10, 2017 at 5:25:44 AM UTC-6, Ron Mc wrote:
Varnish is better for cork grips - it's flexible and
will never exfoliate - 6-7 thin coats
<http://img.photobucket.com/albums/v728/bulldog1935/Raleigh/Viner/f0608392-d452-4b36-97b7-22a1e805d5c3.jpg>
Shellac is for twine wraps - 2 coats
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