On Jan 15, 1:39 pm, "Perry Aynum" wrote:

Rather than going with painted casing, I was planning on using oak.

Painted is almost always the best for harsher environments. You have
to balance wear with appearance, and only you can do that.

My
preference is always clear shellac rather than poly, since the latter tends
to yellow.

Keep in mind that shellac on its own has very little resistance to
water. It will discolor, and in an area where it will be repeated
exposed to water will allow the wood underneath it to discolor. And
while shellac doesn't yellow as fast as poly, it will certainly
discolor.

Will shellac have any problem holding up to that environment? I guess I can
always try it, and if it doesn't work out, just sand it off and do poly.

Ditto all above for you concerns with UV resistance when using
shellac. While a good exterior grade poly has UV inhibitors, shellac
has none. You will be surprised how rapidly the finish will degrade
with exposure to sun AND water. This application is not shellac's
strong suit.

And if you leave the shellac alone long enough to allow the underlying
material to discolor, sanding off the shellac an putting on some poly
will look like a poor refinishing job, depending on how long you let
it go.

Oak can be problematic in its finishing as it is. The large tubules
in oak require a finish that is elastic enough to span its texture
without sacrificing its strength. To get that much shellac on a
project, you will probably need to get to about 6 mil or so, when
dried. (That can be a lot of effort!)

Remember that NOT sealing the tubules closed or using a not-to-elastic
finish will result in a quick finish failure. Even more so in a wet,
sunny exposure area like you have.

Modern finishes are formulated so well these days you have a lot
options. You could use some of the spar type vanishes, polys, etc.,
which will all eventually yellow, but provide good service.

You can apply a polyurethane conversion lacquer which will provide
great service and not yellow rapidly. It is easy to recoat, but
unless you are talking about small areas must be sprayed. (Hell,
spray it anyway!)

There are some alternatives in the water based polyurethanes. Still
little experience on that front here, but the upper end, high grade
products such as ML Campbell, Sherwin Williams industrial line,
Oxford, etc., make some great products that don't yellow.

Shellac as an undercoat is a great idea, especially if you are going
with the big box store finishes like Minwax, Olympic (I wouldn't use
their products) or Varathane.

I believe that the Sherwin Williams products request that you don't
use a primer at all, but put a multiple coat application of their
product instead. The theory there (well tested BTW) is that a clean
finish in proper application sticks to itself better than it would
another product.

If you cannot find the products you want locally, I would go to your
city's biggest Sherwin Williams store. They have so many damn
products I am sure they must have a water based clear finish that is
UV resistant.

I am just now digging into the Sherwin Williams line. With the demise
of my favorite commercial coating supplier here in town, I have been
looking for a new finishing line to use. SW has some fantastic
products. Pricey, but with a professional discount not bad.

As an aside of my personal opinion, I don't really care what I spend
for clear finishes. An ugly looking job is its own punishment. As
you go up the ladder on product quality you will find that many of the
better quality products not only are much more forgiving in their
application, they give a better end product.

Often times you are talking about just a few dollars difference a
gallon to get from OK quality to great. If you have problems with a
product and you get an unacceptable job at the end of its application,
a few bucks at that point seems pretty inexpensive. A trip to a real
paint/coatings store can be well worth the trip to see what is out
there.

As far as the water based stuff goes, you might want to ping BARRY.
He finishes kitchen cabs and the like, and he could tell you about the
issues with MLC products and water exposure. I think he would know if
there was a UV inhibitor for you application.

Robert