In message tcwif.632086$oW2.346600@pd7tw1no
"Ken Moiarty" wrote:

I've been trying to do some sprucing up some assorted fixtures,
moldings, and other miscellaneous household surfaces by brushing on white
Varathane 'Colours In Plastic' (oil based polyurethane) paint.

[snip]

TIA,

Ken

Ken,
Presuming the prepared surface has no contamination of any kind as you
probably know grease, oil etc can create pinholes or craters.

The pinholing which usually leads to tiny craters can be caused in many
different ways, the most common is when paint material is applied too
quickly or too thick, even excessive brushing can cause air to become
trapped, this is more apparent when using polyurethane finishes.

It is possible that solvents may have become trapped in the substrate as
the surface starts to skin dry, blocking solvent release forcing tiny
air bubbles to pop into craters.

Scraping a charged brush on the edge of a paint tin instead of using an
alternative paint tin will in some cases also produce air bubbles.

Air bubbles can be introduced in a paint material by over agitation
during the initial stirring just prior to use.
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.


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