Josh wrote:

8 parts poly to one part thinners for brush application, you get no
bubbles or brush marks. I've been in the refinishing/restoration
business since the 1960's, if works fine.


Aaahhhh. Poly:thinner, not the other way around. I get it.

Does that help with sagging (or make it worse)?

Josh


Sagging/runs tends to happen within about ten minutes of application,
just keep an eye out for it and lightly brush them our with a foam brush.

Mike Wilcox