Spray or Brush Grade

[dik]

If properly formulated, is there an advantage to using spray or brush grade polyurethane coatings? I understand that they both bond to existing coatings by mechanical and not chemical means.

I was informed that the spray grade is less viscous and because of the spray pressure that it bonds to the mechanical roughened adjacent surface better. Is this correct?

thanks, Dik

 

[berkshire]

I do not think there is any difference. The 2 part urethane coatings I use have different thinners, for brushing or spraying.

The primers bond to substrates by mechanical means, topcoats over primers have a time window where some chemical crosslinking is possible, after that it is strictly mechanical.

The spray reducers simply allow for evaporation between paint leaving the gun and arriving at the surface.

The most common method I use for application, is the roll and tip method, where the paint is thinned to a spray consistency,then rolled onto the job, tipped off once only with a high quality brush. This removes the bubbles intoduced by the roller and allows the paint film to stretch out into a high quality finish that looks as though it has been sprayed. It is important to tip only once and quickly as soon as the paint is rolled on or brush marks will be introduced into the finish.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[dik]

Thanks...

Dik