6 replies to this topic

[elf66]

I have done quite a bit of celly spraying in the confines of my garage and found only working on one or two panels at a time to give the best results as it limits the over spray dust settling and giving a powdery finish. When it comes to doing roofs i always struggle to get a decent finish because by the time i have reached the far side,  over spray is settling onto where i started and creating a powdery finish. Obviously it can be flatted back between coats and the finish coat can be compounded back, but i think i must be missing a trick to get this right.

 

I have tried different ratios of thinners and gun pressures and found that with a 30 psi gun, a 60/40 paint to thinner mix and increasing the pressure to about 40 psi gives me a bit longer before the paint starts to dry and pickup over spray dust.

 

I have also tried a fan nozzle rather than a cone spray but it makes little difference to the end result.

 

I guess at the end of the day, i'm just not quick enough at painting large areas!

 

Any tips would be appreciated.

 

 

[Daz1968]

I cant comment for cellulose as I use 2k, but I find the distance from panel and speed of travel is the main factor effecting the paint finish. Dry paint suggests gun distance being too great and paint drying before it hits the panel. Maybe a little late now but last roof I painted I did it with shell on the spit so it was like painting a vertical panel, this minimised dust and overspray.

[Ben_O]

You need to allow the paint to flow so practice the speed in which you pass over the panel and the distance away from it.

 

You need to have long even strokes from one end to the other moving fairly slow but not so slow that the paint builds up and sags.

Make sure you overlap on each return stroke.

 

i find that approx 30cm away from the panel is a good distance.

 

You need to move fairly quickly to cover big panels but if the paint is going on wet enough, you should find that you have minimal overspray

[elf66]

Thanks Ben,

 

I guess i'm just not quick enough!

 

Its not a problem on small panels but i hate roofs!

 

I think the problem is compounded by lack of ventilation, i cant get any decent through draft without getting crap in the paint. I can at least polish out overspray rather than bits of vegetation or insects in the paint!

 

I might try treating myself to a decent gravity feed gun that puts the paint down quicker that the ancient devilbis pressure feed/ bottom pot gun i have been using for years!

[Homersimpson]

40PSI sounds a bit low to me, I use a Devilbiss JGA (suction type) and have found (With 2K) that anything less that 50PSI causes the paint to be dry, powdery and thin. 

 

I would spray with a wide fan on the gun to do a roof, around 30cm from the panel and overlap each pass by half with the next one.  The main advantage of a roof is you can get the paint on quite heavily in the majority of the roof without too much risk of runs or sags.

 

If you do get runs there is a brilliant little tool that helps get rid of them which can be purchased from here:

 

http://www.ebay.co.u...kQAAOSwWxNY24W1

 

Unlike a run razor this gently removes the run or imperfection without damaging the surrounding paint, you can then flat back and compound back up, only problem can be that if the run is large the pigment can run out of the colour and when you file it back and compound the run is gone but a mark exists where the pigment is missing.

[slidehammer]

There is a spray painting channel on you tube called The Gunman, which is really informative as he does commentary and runs through his gun setting, which admittedly are always for 2k but you can get an idea of speed and distance from the panels. Also starting at a side and working to the middle of the roof and then going around the car and working from the centre out will help maintain a wet edge. I would suggest you need to keep he gun pressure down more for the gutter areas to prevent it blowing straight back out.

[Shifty]

I paint from the gutter to the centre of the roof, rather paint the entire length both sides.

 

I find this a lot easier than doing it the conventional way