On 3/19/2013 10:08 AM, Swingman wrote:
On 3/18/2013 6:48 PM, SonomaProducts.com wrote:
You're done.

After the second coat you have a finish that will last a lifetime
unless it is a bowling ally or highly used table top or other high
traffic surface.

Not necessarily.

"Thinning", which he admitted to doing by approximately 50%, simply
means the layers of poly he applied were 50% thinner, meaning more
layers/coats are need to be applied to reach the same level of
protection as the unthinned product.

When contracting for a polyurethane hardwood floor finish I spec four
coats when "thinning" up to a maximum of 25%.

In his situation about the only benefit of thinning the poly is faster
drying.

As usual, I'm confused.

I have read that "wiping poly" is a popular and relatively foolproof
method of finishing. "Fool-proof" has an attractive sound to it for a
project with a lot of surface area to cover and me (yes, the "fool") in
charge of the application. I'm at least theoretically willing to
experiment with more sophisticated approaches, but not when I'm
finishing the better part of four sheets of plywood (plus the face frames).

My sense of it is (or at least *was*) that the thinned product, coupled
with the "wiping" application method, helps give a smooth even finish
without the need for much expertise. No brush marks, no puddles, no
bubbles. And in fact, I am quite pleased with the finish I got on the
bookcase boxes. It's smooth, even and doesn't look at all "plastic-y" or
thick. Could I really have gotten similar results with half as many
coats of the full-strength poly? I have done that in the past and have
not gotten as nice-looking a finish as I'm seeing now.