On Thursday, April 22, 2021 at 4:31:43 PM UTC-4, Leon wrote:
On 4/22/2021 3:20 PM, Leon wrote:
On 4/22/2021 2:48 PM, no one wrote:
Like an idiot I stained and finished our new wood window casing & sills
with Shellac several years ago. Now of course the sun & exposure has
pretty
much taken their toll & I need to refinish.

I don't want a urethane since that yellows over time. I was thinking
about
a pre-cat laquer or a water based polyurethane or varnish. Any
preferences?
I'm leaning to the poly. It will be brushed on.



Unless you use an opaque finish like PAINT, the sun will continue to
takes its toll on translucent finishes.
And to take this a little further, you say that you do not want to use a
urethane finish. But then mention possibly using a polyurethane.

Polyurethane is urethane with additives.
If you do not want urethane, you also don't want polyurethane and or "poly"

Urethane's and polyurethane finishes do not necessarily turn yellow over
time. Oil based polyurethane finishes tend to yellow immediately and
more so over time. Water based polyurethane finishes tend to be crystal
clear and remain that way.

Minwax oil-based Wipe-On Poly doesn't yellow.

The can calls it "slight ambering". ;-)

(Gotta love those marketing folk.)

Varnish is a relative broad and generic term for most any relatively
clear finish including "shellac".

Finishes that allow sun to penetrate, relatively clear finishes, will
break down more quickly than opaque finishes, like paint. Paint does
not allow UV rays to penetrate like clear finishes.