Postby John Rickett » January 29th, 2012, 7:01 pm
The viscosity of the paint can be reduced with extra thinners, however the problem lies not only with the temperature of the paint but the surface to be sprayed. In this country, if its cold then almost certainly there will be a high humidity and if the dewpoint is reached, a thin layer of moisture will be present on the surface. There is also a risk that handing the piece to be painted will cause moisture from your hands to be deposited and which will not evaporate. If sprayed on, especially if the surface is impervious, the moisture will be trapped and will manifest itself later on by small bubbles appearing.
Even if you spray when the air is close to, but above, the dewpoint (100% relative humidity) the evaporating thinners will lower the temperature a bit more and may just trip you into 100% RH, causing moisture to form on your beautifully painted surface.
If you really must paint in the cold, choose a sunny day and mid-morning time when the temperature is rising - don't try to paint at 3 o'clock in the afternoon unless you can then get the painted piece into the warm to dry...........or as Bob says, wait until Spring.
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