I am going to build a 20x20 outdoor pavilion out of walnut. How can I preserve the walnut color without it going grey. It will be built with green wood, can I treat green wood with anything? How can I build this thing with green wood and keep its walnut beauty?
Ronnie,
There is several products. LandArk exterior finish, Permachink wood finish, spar urethane, etc. A lot of people are against spar urethane because it can blister. I used ready-seal on several products and it has worked well. Something like walnut deserves a higher quality product ;D
Oxidation begins the instant that the log is opened. The lumber immediately begins to loose it's green color and turns brown. Even if you can seal it to prevent further Oxygen exposure, you will still have the Sun's UV rays to contend with. Sealers like "Helmsman Spar Urethane - Exterior Polyurethane" have UV "inhibitors", but they are not "preventers". :-\
I guess I am wondering if theres any point in building it out of walnut? If its going to turn grey and I have to stain it to give it some color it may not even be identifiable as walnut? Was hoping maybe someone had built an outdoor structure using walnut.
It should not turn gray like Oak or Poplar, but get darker. Darker could be good.
I thought I had heard that dark woods lighten with age and light wood darken with age.
Jim Rogers
There are quality finishes available for protecting a species like walnut, but you can not use non-dried wood. Epifanes is a finish used by the best boat builders, and I have used it several times on exterior projects. It is fabulous, last a long time, but nothing lasts forever. The finishing schedule is grueling, with 7 coats applied, and plenty of wet sanding work in between. It is spectacular, but labor intensive, and quite expensive.
Short of that, I'm not familiar with any product that will work on "green" walnut that will last.
Walnut is a beautiful wood, but there are better choices for exterior uses that will hold up to the elements much better.
Not what you want to hear, but I can only tell you what I've learned in a career of woodworking.
If you learn of something new that works well, please let us all know. Walnut is one of my favorite woods.
I've never tried walnut outdoors but my understanding is that it is listed as quite "durable".
https://www.fpl.fs.fed.us/documnts/TechSheets/HardwoodNA/htmlDocs/juglans2.html