Architectural HVLP

[Alex Horvath]

Hi all,

I installed lots of new trim in my house and decided to paint it with HVLP using Ben Moore alkyd SI. I can get a near perfect result brushing SI on trim but on flat/wide surfaces like stair risers, wide jambs etc. the brush marks are fairly obvious.

The learning curve on spraying SI was huge partially due to some misinformation but I pretty much have it nailed now. If I had to do it again I'd use a product that's designed for spraying like Campbell etc. although I don't know for a fact that it would be any easier... I check the viscosity very carefully with a Ford viscosity cup every time I thin because it seems like a knife edge between overthinning (runs) and underthinning (poor flow out).

Anyhow, my question is - how is overspray handled if at all?

I don't mean overspray in the sense of going wide onto the walls as I had a pro told me there is no issue with applying the latex wall paint over the alkyd on the wall. I'm referring to the "fog" that tends to settle on all wet horizontal surfaces and my concern is that it will mar the finish as I go along. It's not a really an issue now because I'm doing a first or second coat piece meal but I plan to come back for a final coat (in the one large room I'm doing) and it takes a couple of hours to spray it. Of course I cover any previously painted surfaces.

I know that part of the purpose for spray booths is to get rid of overspray so it does not land on the finish. Perhaps it does not really matter with alkyd since it takes so long to dry and the fog just becomes part of the finish but my sense is that it dulls the finish and alkyd SI is already a little dull for my tastes.

I could place a box fan with a furnace filter attached in the doorway with plastic surrounding it. I'm a little concerned with nearby cars although I think the spray is so fine it drys fast in that state. I have gotten alkyd si overspray on a car (forgot to close door to garage) and it wore off pretty fast but the neighbors might not be so accommodating. Is a furnace filter fairly effective at capturing the overspray or is there something I could add to it to further reduce the fog that gets past the filter?

Thanks

PS. I just got the 3M PPG system from Homestead (for a Accuspray 10G)and it's worth every penny. I was always afraid of paint leaking from the cap (the gaskets barely survive one cleaning) and I always seem to get paint in the breather hole. I can tilt the gun any direction now to hit awkward jambs and base molding.

[Lex Boegen]

Just a thought here (meaning that I've never done it)--why not use pleated paper furnace filters? They filter particles out as small as a few microns. They do reduce the air flow because they're more restrictive, but if you duct taped five of them together to form a box, and taped the open end of the box to the fan, you should get sufficient volume of air through it to effectively filter the air.

[Alex Horvath]

Thanks,

You're right I need to look at the filters - I have always had an electrostatic and I just kind of assumed that furnace filters are very poor filters. I had no idea thay have micron range units.

The fog is really quite light so I don't think I need much turnover.

I have seen huge stain grade trim/paneling room installs on wood web that were installed unfinished and assuming they were finished with HVLP they must employ some method like this.

[Phil Phelps]

I wouldn't spray alkyd paint from a HVLP inside an occupied home. The fog it creates is very flamable. A box fan used for exhaust purposes is dangerous. We are in the winter months and it takes longer for paint to dry. But, even in a warmer climate, alkyd paint takes a day to dry to the touch. The best way to spray alkyd paint is with an airless and a fine finish tip. But, I have a large spray room with a commercial exhaust fan. I wouldn't do this in my home. Have you tried using Penetrol with your enamel paint? You can paint door casings and base moulding, flawlessly, adding Penetrol and using a fine, china bristle brush.