Finish won't Dry
The Problem:
Finish drying too slow.
The Cause:
Temperatures below 50 degrees F. (10 C) and relative humidity
(over 90%) covering the floor with brown paper or cardboard
before it's dry. Oil Modified Polyurethane dries slowly when
the floor temperature is at or below 50 degrees F. (10 C) when
humidity is over 90% RH. (A combination of both makes conditions
worse) all of these points prevent the solvent from leaving
the wet film. Contaminants in the grain or between the boards,
can also be the cause for slow dry.
How to fix the problem:
Determine which of the above, or combination of, is the cause
of the problem.
Remember to stop the A/C (close windows and doors) 30 min.'s
prior to application then re-start (reopen) when the finish
is tacks free. Which, is usually after about one to two hours
for Oil Modified Polyurethane, and 15 to twenty minutes for
waterbased. After these corrections to the site conditions have
been met, the main ingredient is time. DO NOT attempt to screen
the floor until the finish has completely dried since this will
cause deep scratches in the finish and will remain visible.
You could also experience solvent entrapment, causing a tender
topcoat, which is a cause of early wear. A complete re-sand
is the alternative.
How to avoid in the future:
A simple tool such as a hygrometer will tell you what the job
site condition is and therefore you have the opportunity to
act accordingly. Dura Seal recommends changing your expectation
of the dry time if your application and drying conditions vary
from…
The coverage rate on the label (see Finish
and Curing Parameters) (JoeAl please link this)
A temperature above 70 degree F (25 C) and Relative Humidity
below 50%.
Note: Dry times either fast or slow are affected
by Temperature, Relative Humidity and Air movement, either natural
(window) or forced (HVAC) PLUS coverage rate. Attention to these
details improves success rates.
