# Applying polyurethane with a brush soaked in mineral spirits



## dpitch40 (Sep 7, 2018)

It was my understanding that when applying oil-based polyurethane finish, I should dip the brush in mineral spirits beforehand to keep it from getting stiff and loaded with the poly. It is working for this purpose, but the problem is when I start applying the poly, the first several square feet I apply are mostly mineral spirits. The coat looks fine and shiny when I brush it on, but most of it soon evaporates, leaving very little finish behind. Was I mistaken about this? Or else, how should I keep the mineral spirits from diluting the poly in my brush?


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## John Smith_inFL (Jul 4, 2018)

no no no no noooooooooooooooooooo

all you are doing is diluting the first area greater than the rest of the coats.
you can "rinse" the brush in MS - but then, beat the heck out of it to remove
as much MS as possible before you start painting.
you should never put a brush in a container of thinner that covers more than 
the bristles. . . . 
let the finish dry thoroughly, lightly sand, then apply your successive coats
with a dry brush. if you choose to have a MS soaked brush before you start,
beat it aggressively to remove as much MS as possible from the bristles.


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## Steve Neul (Sep 2, 2011)

I think you miss-interpreted the practice if wetting a brush prior to starting the finishing process. You wet a new or dry paint brush as though you were cleaning it and shake out the excess solvent prior to painting. This makes the brush easier to clean after you are done. It has nothing to do with with the finishing work. By dipping the brush and then the varnish you are severely diluting the varnish. You can dilute a finish to the point you screw the integrity of the finish and that might do it.


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## Quickstep (Apr 10, 2012)

You can spin the brush by rolling it back and forth between your hands to get it spinning. There are also brush spinners available for this purpose. It will remove most of the excess so it doesn't dilute your finish. Best to have the brush in a can to catch the spray.


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