"Stephen Hull" wrote
[...]
Air bubbles can sometimes be avoided by not over brushing and should be
eliminated completely by adding a little raw linseed oil to ease off
the faster drying properties associated with polyurathane finishing.

Steve.


Hmmm... Raw linseed oil to delay drying, eh... I'll be giving this a try.
I didn't know I could delay the drying time of Varathane, being that,
ostensibly, unlike ordinary oil-based paints polyurethane solidifies not by
solvent evaporation but by the chemical reaction of isocyanate reacting with
the moisture in the air (which, as an interesting aside, is known to release
CO2). Yet, there's obviously already some oil in this "oil-based"
polyurethane product and this may, for all I know, perform discrete
functions beyond the obvious. So who knows? It seems to me that this
Varathane sets up so quickly, losing its ability to flow freely so soon,
that the holes left by the bubbles don't have a chance to fill themselves
back in. So maybe this will be the key. Thanks.

Ken