# Spar Urethane - Minwax vs. Varathane



## tjaburke8

I was looking through some articles on the best poly to put on some outdoor furniture, and I think I've settled on water-based spar urethane.

Can anybody give suggestions as to Minwax vs. Varathane for the spar urethane? I could try both but prices vary and I'd like to just commit to the best.


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## JAAune

I've not used Varathane but every other brand of spar varnish (including Minwax) I've used that came from a bix box store failed to hold up more than a year outdoors. Le Tonkinois is the next product I intend to use if I need to finish an outdoor project. An acquaintance informed me it's held up for three years on an exterior door which is far better than anything I've finished with spar varnish.


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## Rick Dennington

Don't use a spar varathane or urethane…..It won't last on outdoor furniture…You need to use a good quality Spar Varnish…..Get a qt. that says Exterior/ Marine Spar or Super Spar Varnish…..It will hold up to the elements with about 2-3 coats….I use it alot on outdoor projects, and no problems so far…...It has to be Exterior/ Marine..


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## tjaburke8

> Don t use a spar varathane or urethane…..It won t last on outdoor furniture…You need to use a good quality Spar Varnish…..Get a qt. that says Exterior/ Marine Spar or Super Spar Varnish…..It will hold up to the elements with about 2-3 coats….I use it alot on outdoor projects, and no problems so far…...It has to be Exterior/ Marine..
> 
> - Rick Dennington


The spar urethane I've looked at all says exterior. But you're saying use exterior/marine spar varnish? So varnish, not urethane. Does exterior vs. marine matter? I know marine is used for boats and such - is one stronger/preferrable to the other?

Do you have a brand that you know works well that you'd suggest?


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## Dal300

*Rick Dennington* It doesn't matter what you use for outdoor furniture. The seal will not be perfect. You will redo the finish every few years.

*tjaburke8*, A few years ago we were living in an RV full time where we traveled around for about 7 years.
The first year I was forced to replace the entrance steps because the originals were something like the cheap Sauder furniture…. coarse particle board.

I was given a load of used red oak flooring and I had the strange idea to repurpose it. It was probably about 100 years old from being cut, so I used the best pieces to build some beautiful steps.

The trouble is, it only had some kind of floor varnish and wax that had all worn off.

I had several cans of different spar urethane that weren't very old and had used on a project for a customer.

I did our galley, our lounge, drivers area and head. I was about out so I decided that for the steps I would use the last of the rest of the cans in different areas.

The Minwax Oil base Spar Urethane was on the bottom step, the Varathane and Water based Minwax were split between the second step and top step.

I did take about a week doing these steps making a half dozen different coats.
The bottom step wore in about 18 months, ( I figured it got the worst of the weather). The second and top step lasted almost the whole seven years before the moisture discolored the oak and the finished flaked up.

Seriously, I didn't see much difference between the Varathane on the left side and the Waterbase on the right side. 
The biggest problem I saw was where I had taped off in the center and the line wasn't always consistent.


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## Rick Dennington

It really doesn't matter what brand it is, just a long as it says Exterior/ Marine…I've used a couple of different brands…The one I'm using now is Cabot's, but that's just personal preference…There's a few out there, but they won't all be E/M…..I ran out of a E/M Super Spar Varnish, but I can't think of the name of it…...But…nothing last forever….You'll have to refinish projects every couple of years or so…..


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## Wildwood

Spar varnish simple mixture of;
Oils - Linseed Oil or Tung Oil
Resins - Alkyd, Phenolic, or Polyurethane
Solvents - Mineral Spirits, Naptha, or Paint Thinner

Your better grade Marine spar varnish contain Tung oil.

What Varnish Should I Use For My Job?
To determine what type of varnish you should use for a particular job, you must look at what type of oils and resins are contained within a varnish and what the ratio of oil to resin is. Varnishes that contain a larger amount of oil to resin are called long oil varnishes. Varnishes that contain a lower amount of oil are called medium oil varnishes. Long oil varnishes are more flexible than medium oil, but also softer. Medium oil varnishes are harder, but are more brittle. For exterior us e, a long oil varnish is best. Because it is more flexible, the varnish will expand and contract with the wood as changes in temperature and humidity take place. A medium oil varnish will not move as much and therefore as the wood moves and the varnish does not, the varnish will soon start to crack and peel. Medium oil varnishes are best used indoors where a lot of wood movement does not occur and a harder finish is desired. The resin contained in a varnish is also important in determining what type to use for your project. Some resins are more elastic than others, making them best suited for exterior uses. Phenolic resin is more elastic than other resins, therefore it will be able to withstand the extreme wood movement of exterior projects without quickly breaking down and cracking. Alkyd and polyurethanes are better suited for interior use. Not as important, but still a factor is what type of oil is used. Tung oil is more water resistant than linseed or other oils, therefore it would be a better oil for exterior use, but much more expensive.
Putting this all together, we basically come down to two categories, interior and exterior use. For exterior use, a modern spar varnish which is long oil and is made up of tung oil, Phenolic resins, solvents, dryers an Ultra Violet blockers (to protect the color of the wood from fading) is probably your best choice.


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## Rick Dennington

Dallas…...In your case I can understand why the finish didn't last long….If you continue to rub on something constantly, finish is gonna wear off eventually….In your case, rubbing on RV steps with your shoes did it in…..


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## AlaskaGuy

Check out this post at the WoodWeb's professional finishing forum.

http://www.woodweb.com/cgi-bin/forums/finishing.pl?read=769630


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## wapakfred

This only echos some of what has already been said: stay away from anything that has urethane resins in it. True marine spar varnishes or untinted exterior oil paint will hold up the best, but as also already mentioned eventually it will need to be repaired as well. Some of the newer waterborne finishes may do well for you is you can't get the oil based, be aware: some of them have a small dollop of urethane, apparently just so they can put that friggin magical word on the label (IMHO), but they are all primarily acrylic resin finishes, and many are very good quality. If you think you might be interested in the untinted paint (if you can get it it will almost certainly be cheaper than marine varnish) check this out. But oil based paints are getting harder and harder to find in most of the country.


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## OSU55

The US Dept of Agriculture has done a lot of research for outdoor wood preservation. The series of documents I found from 1995 were titled " The finish line". There is information on some waterbased paints and stains from that time period. They found latex house paint is the best. Below is a quick summary of their findings:

Life span of different kinds of finishes:
Water repellents 6-12 months
Clear water-repellentpreservatives 1-2 years
Pigmented water-repellentpreservatives 2-3 years
Varnish 2-3 years
Solid-color stains 3-7 years
Semitransparent stains 3-8 years
Paints 7-10 years


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## bobasaurus

I've heard countless reports of spar urethane (including "minwax helmsman") just peeling off of outdoor wood projects after a few months/years. Apparently it can't hold up to the constant UV and humidity changes. A marine spar varnish for boat use might work better, but I'd lean towards using a penetrating oil and just re-oiling every few years. The oil will soak in and never peel.


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## buildingmonkey

I built a wood sign for a neighbor, used white oak, glued with titebond 3, routered the letters into the face and painted the letters with white paint, planned to finish it with spar urethane till reading this thread. Some guys have recommended used motor oil on it, and I remember once an woodworking article in a magazine recommending linseed oil, with melted parafin added, and thinned with paint thinner. Anybody familiar with that for a preservative?


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## wapakfred

That is essentially the finish I use on my workbench, assembly table, and the tables on my RAS. I substitue beeswax for the paraffin, but it's otherwise the same. It's very good in this use, glue pops right off, no flaking/peeling, and easily repaired. I suspect it would have the same advantages outdoors, though it would have to be redone more often. A lot of guys just use linseed oil on tool handles, and redo it often. I'm wondering if the wax might might be a problem in the hot sun if it was on a seat. That could be a real mess


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## RogerBean

I've lived in a log house for the past 30 years. I was told initially that the paraffin, linseed, thinner mix was a good exterior finish. NOT! After a couple years of Michigan exposure, the logs turned virtually black. I've also seen exteriors done with a varnish, film forming finish. They invariably crack, flake, and turn milky. Marine just takes longer as it has UV inhibitors. The only way to avoid this continual removal/refinish cycle is to go to some form of "transparent exterior stain" like that by Cabot or Behr or others. Imparts a light color, is UV resistant, and will not form a film that will degrade. On the house it lasts up to eight years. I then remove the outer surface with a 3000 psi pressure washer to remove the exterior surface, then respray the exterior with new transparent stain. Looks like new again. But, this is not a shiny finish.

Film forming finishes (varnish etc.) are difficult to remove for refinishing, and the frequent sanding etc usually pretty much ruins the look of the item over time, as you pretty much have to sand/sandblast the film off. But, it you desire a shiny, exterior film finish, the marine varnish is probably the most durable. Probably get two or three years of exposure before it looks bad.

I do not believe there really is any "great solution" for the exterior. Just troublesome and worse.

Just my experience. Hope it is useful.

Roger


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## AlaskaGuy

Read this.

http://www.askhlm.com/Articles/ArticleViewPage/tabid/75/ArticleId/1/Marine-Varnish.aspx


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