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Is spar varnish and spar urethane the same thing


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#1 trout78

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Posted 06 December 2007 - 01:43 AM

Is spar varnish and spar urethane the same thing?

#2 timmy

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Posted 06 December 2007 - 02:58 AM

I'm ready to be corrected on this one (We don't have "spar" varnishes in the UK) but my understanding is that spar varnish will be a traditional tung oil based varnish and spar urethane will be a good quality marine PU based varnish.

Tung oil varnishes are traditional, give a nice mellow tone, but take an age to cure.

PU varnishes are sometimes a little less fussy to apply, cure more quickly, dry a bit harder and are very clear, some say too clear.

Cheers,

Tim.

#3 phg

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Posted 06 December 2007 - 09:27 AM

I think the original spar varnish was just a mixture of boiled linseed oil, pine rosin and turpentine. It was used to dress the spars of a sailing ship to minimize the effects of weathering, hence the name, spar varnish. Marine varnish is the same thing.

Modern marine varnishes are more sophisticated, but are generally separated into two categories, those using alkyd and natural resins, and those formulated with polyurethane (PU) resin. Typically, the PU based varnishes are less durable when exposed to the elements, especially direct sunlight, but for short term exposure, as a fly rod receives, are good enough.

I have used both on my rods, and have yet to find a reason to prefer one over the other, except perhaps tradition. Ease of handling, appearance, cleanup, availability and cost are all about equal.

#4 Bowbiker

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Posted 06 December 2007 - 10:00 AM

Here is an excellent read on the subject. Cleared up a lot of different "unknowns" for me. thumbsup.gif



http://www.taunton.c...ages/w00060.asp


Dick Seymour

#5 roadking

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Posted 06 December 2007 - 11:10 AM

Dick, that is a good read. A lot of info, saved as a favorite. Thanks.

Mike

#6 testwood

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Posted 06 December 2007 - 07:16 PM

Hi - International Yacht Varnish is a very well known brand in the UK. A couple of weeks ago I emailed them to ask if their varnish contained tung oil, they replied no. I emailed again to ask if it was PU based they replied no. I really feel like asking 'what the devil it does contain'. You sound like a chemist phg what other sorts of varnish are there?. dunno.gif

#7 FlyDoctor

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Posted 06 December 2007 - 07:54 PM

You need to do some research on their website at http://www.yachtpain.../uk/default.asp . According to what I read Intl Schnooner is a traditional tung oil varnish whereas Goldspar is a polyurethane varnish. Here in the US it is sold under the Interlux brand name.There is a lot of info on these if you just dig around. Took me a couple minutes to find just this doing a Google search--Larry

#8 phg

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Posted 07 December 2007 - 08:01 AM

No, I'm not a chemist, but I've been a woodworker for more years than I like to admit. As for that varnish, it's interesting that they didn't tell you, in general terms, what it contains. You would think that it would be a marketing point. Anyway, the drying oil in varnish is usually either tung, linseed or walnut oil, with linseed being the most common, or should we say the more traditional.

#9 testwood

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Posted 07 December 2007 - 03:30 PM

Hi phg - As a woodworker you can appreciate how I treasure these old planes that I inherited from my dad who was a cooper. Still keep them sharp and give them a runout occasionally.
IPB Image

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#10 roadking

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Posted 07 December 2007 - 05:25 PM

testwood, what a great collection. Glad you use them!

Mike

#11 phg

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Posted 08 December 2007 - 08:31 AM

I love those old wood bodied planes! wub.gif Great collection. My grandfather was a cabinet makers, and I have a few of his planes, which I do use ... carefully. Properly tuned, they are as good as anything out there today.



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