Urethane vs varnish

[Randy C]

Is spar varnish and spar urethane the same thing? If I want to blend an oil/BLO/varnish can I use spar urethane instead of spar varnish or should I use just regular varnish?

Thanks

[Scoony]

No, not the same. Someone will come along and point out the differences, but for a varnish, BLO mix, I like to use Sherwin Williams quick dry varnish. I have tried urethane and did not get as nice a finish.

[jteneyck]

Varnish is nothing more than a resin and oil that are cooked until they turn into - drum roll, please - varnish.  You can use lots of different resins and oils, but the typical resins are phenolic (Waterlox), alkyd (PL 38), or urethane (lots of companies). 

So is spar varnish and spar urethane the same thing?  Could be, but doesn't have to be.  But you can use spar urethane to make your own oil/vanish finish if you want. 

John

[MikeBob]

Why do you want to add BLO to it? Spar anything usually just has UV blockers in it.

[fredhargis]

To add (and maybe repeat) to what was said above, the mixture cooked to be varnish consists of a resin and a drying oil. Like John said, the common resins are polyurethane, phenolic, and alkyd. The common drying oil is linseed oil, there is one that uses soya oil (P&L 38, a really great product if you can find it), and maybe one that uses tung oil (or some mixture of the 3). What makes a varnish "spar" is that it's a "long oil" formula that gets cooked; long oil means it has a higher content of oil in the mix. This gives it the flexibility it needs for outdoor uses, like the spars on sailing ships.......hence the name. "Spar varnish" does not imply UV absorbers, though it's pretty common for them to have some. I know Flexner wrote once that he tested the UV characteristics of them, he concluded that at least one (Helmsman) indicated it had the UV absorbers, but performed so poorly he speculated it had none. You could use the spar for your danish oil mix, but it would likely be way softer than just using a regular varnish. Someone mentioned SW FastDry Oil varnish, that's another great product and is an Alkyd resin/linseed oil formula.....very good choice.

[Randy C]

You guys must have much better sherwin Williams' than I do. Went to two different sw's and they had never heard of sw fast or quick dry varnish. All they have is min wax poly and urethane.

[fredhargis]

It's not uncommon for the SW folks to know nothing beyond wall paint. Show them this link.

[Randy C]

Thanks Fred. I don't think I specifically mentioned it but I am looking for something for my big green egg table which will be outside under a covered porch. This product says interior so I assume this would not work

[fredhargis]

I agree, it has no UV inhibitors. How about considering soemthing different for your table...untinted paint. If you get the paint base for deeper colors (#4 in most brands) without being tinted it dries looking very much like varnish (oil based) or maybe even water clear (acrylic). Get the exterior formula and it will have the outdoor protection you want, will be easier to apply than a true marine spar varnish, and be a lot less expensive. Mac (Kevin McReynolds) used the SW A100 exterior acrylic, and got the water clear look on a walnut cross that was placed outdoors..last check it was doing just fine. If you're interested, more info here...though the article is just a little dated (some brands have changed the finish names, oil base is harder to find, etc.).

[Randy C]

THanks again Fred.

I will go by SW and see if I can get this. Last year when I was trying to get a finish for my adirondack chairs I went by and inquired about this and they acted like there was no such product. I explained that several of my cohorts on Woodnet had purchased this from SW and even printed off some of the messages explaining the product in detail and they still said this product did not exist.

Unfortunately, the employees at my two local SW's are not very knowledgeable and do not go out of their way to be helpful