OT - Spraying Base Coat
Turbo Mini Forums

I'm a bit embarrased asking this due to being a machine painter by trade, but i dont ever use base and clear at work.

I'm having problems laying the base down evenly it keeps coming out blotchy or mottled, i.e dark and light patches.

The gun is a DeVilbiss GTI 1.3 tip, using around 40 psi. Paint is octoral.

Any one able to shed anylight on what might be going wrong?

You want 2 bar pressure, make sure the air hole in the pot isnt blocked, have you thinned the base? or is it pre - thinned? Metallic or straight colour?

(Im off to work now, so Ill think about it some more during the day)

Paul

Edited by paul wiginton on 18th May, 2010.

I seriously doubt it!

Ok will revert back down to a lower pressure, air hole wasn't blocked as it was a brand new gun used for the first time.

Its specified as needing to be mixed 1:1 with thinners supplied by the supplier. Once thinned is about the viscosity you would expect.

Metalic blue Rover JAM

1:1 with thinners is about right, hardener is NOT used in base coat, metallic does come out blotchy - its the technique that makes it even which is hard to explain. Hold the gun about 12-14" from the surface to be painted and use even strokes flicking the wrist away from the panel at each end. You need to build up layers, usually 3 normal coats then a 'drop coat' where you hold the gun about 24" from the surface and dust the paint on, this allows the metallic particles lay in the same direction which stops it looking blotchy or streaky.
Lacquer as normal

Paul

I seriously doubt it!

i'm assuming this is celly paint then? Ive never sprayed celly but done loads of 2k where the base coat is 2:1 with hardener.
Paul

"I'll get there in the end"

Some solvent base is 2:1 and others 1:1, depends on brand.

all paint and thinner NO hardner.

Laquer usually 2:1 or 3:1 10% thinner

celly is usually how ever much thinner you fancy, very old school before my time.

Basicly as wiggy says.

rick

Have given the base another good 3 coats tonight, the drop coat method seems to have helped, not heard of that before.

Am using just base coat and thinners, so no worries there about hardener issues.

Any way its not perfect but better than it was, was struggling to get the base coat to cover properly for some reason. Guess you get what you pay for, buy paint half the price of elsewhere and get half the quality.

Think i'll try and stick to solid colour i reckon.

"I'll get there in the end"

What paul ha advised is bang on the only modification I would make is to turn the paint down a little.

There are two methods of drop.

1. Holding the gun horizontal to the panel, spraying and leting the paint fall/drop onto the panel.

2. Hold the gun as if normal but as paul described above.

what your trying to do is to allow the paint to sprinkle on to the panel, just like sciving iceing sugar onto a cake.

Turning the paint down will also help reduce the possibility of you wetting the surface which is what makes the metallic look streaky or blotchy.

Becarefull how much product you put on as you may descover micro blisters. Re-work is a bitch!

Own the day