I'm new here...dirt in paint question

[Motorcar]

I have finally taken the plunge and started to hands on learn to paint. I bought a Binks M-G HVLP gun and am trying my skills on the engine bay of an MGB for the moment. It had been media blasted, so I primed it in epoxy primer, then a urethane filler/primer.
Now as for the color coat. I am using single stage Glaserit Acrylic Urethane. (per Lens recommendations) There is quite a bit of what appears to be dust/dirt in my paint finish. (click the link below for example)

At the moment I am forced to paint in my good old garage. The very same garage where I repair and restore cars....welding/grinding and general mayhem.
I have tried to clean the place out, put up plastic sheeting on the walls etc...
My question is will this dirt be something I can color sand and buff out, once I get to painting the actual exterior of the car? Or do I need to come up with a better
"spray booth"?
Thanks
Pete

[Robert]

The trick with dust nibs is to blend the nib into the orange peel so it doesn't stand out. If you cut too flat you'll make a spot that doesn't match the rest of the panel.

So, just cut with 1200 grit till the nib is gone and you are just touching the tops of the orange peel. Then sand with 2000 with no block and buff out your scratches.

Take Care,
Robert

[Mooch]

Motorcar you need to come up with a better spray booth. It will make your painting much easier. Mooch

[Len]

You can paint in a cave on a dirt floor and get clean paint jobs as long as you can control some of the variables.

First you need to realize the MOST dirt is probably coming from the car and not the environment so teaching yourself to look for dirt traps and removing the dirt is the number one focus.

Secondly, if you do have dirt in your paint that came from the nooks and crannies that hide it, you can either sand and polish or sand and repaint because most of the dirt has probably blow out for it's hiding places and done it's damage. Your next coat will probably be cleaner and in an engine compartment I'm usually a fan of repainting rather than sanding and polishing, it's usually quicker and easier. However, if perfection is needed then polishing is usually the way to go.

Try to follow a good procedure for cleaning the car by...
1. Washing the vehicle with warm water and mild liquid detergent before starting your prep work.

2. Use a good dedicated solvent cleaner (grease and wax remover) to wash the surface. Use a pump sprayer or one similar to the one below to apply the cleaner then absorb it off with paper towels. Use an entire roll if necessary, it's cheaper than having problems.

3. Sand the paint then wash again with water and no soap.

4. After the water is dried from the surface touch up and spots that still need sanding then mask the vehicle.

5. Using low mid-pressure air (25 to 35 PSI) blow out all the cracks and crevices then wipe the surface as you blow this same pressure under the clean cloth you're wiping with.

6. Mask the vehicle.

7. Prior to spraying blow out the cracks one more time using low pressure air (20 PSI or less) then blow off the masking material then the surface you'll be painting. Blow out the cracks and across the surface one more time.

8. Use the grease and wax remover one more time by spraying and wiping then entire exterior.

9. Mix your paint and right before you're ready to spray use a "good" tack cloth (properly) to carefully pull any remaining dust off the surface.

10. Spray.

The room and your clothing should be prepped prior to step #7. Blow off the walls, dampen the floor, put on clean protective clothing and breathing apparatus. When you move around the room be aware that you are causing waves and eddies in the air that can pick up dust from the surrounding surfaces so move gracefully and try not to cause too much turbulence.

Solvent Sprayer Link


Good Tack Cloth Link

[BenWillis]

Pete, That really looks like sand left over from blasting the bay. Having just blasted a whole AH Bugeye and started primer/paint I can feel your pain. Jut do as Len said and try to identify and remove any dirt/sand from its hiding places.

Ben in SC

[Steve g]

I would agree. I can't be sure from the pic, but it looks too close together and too regular in size and shape to be airborne dust that settled on your wet surface. Are you sure it's not debris (water?) from your gun? I've had that happen. I paint in less than ideal conditions as well and i found that since I went to Nason's 496 clear which sets up fast yet flows out nice I have far fewer problems with dirt in my paint.
Steve g.

[Motorcar]

Thanks for the input. I certainly have a rather dirty car, other than the engine bay, so thats gotta be an issue. There is sand everywhere!
I also wasn't wearing any kind of tyvek suit or anything, just a nasty old flannel shirt.
I will tidy things up a bit!
Pete
By the way Ben...I also am working on a Bugeye. Just had it blasted and am doing rust repair right now. Email me if you would like to compare notes.