The Spray Painting Thread

["Z" UTE]

Owen, yep, too many layers of paint lead to problems of cracking and crows feet. Soda blasting simply removes the paint without too deeply etching the metal. An engine bay would be the best possible example of where to use soda blasting. Imagine the time it would take to sand into every corner and crevice of the bay.

Sand blasting is effectively shot blasting on a miniature scale, so the metal cops a hammering. The normal media in "sand" blasting is granulated mineral. Soda ash/bakeing soda is a sharp edged fine grained water soluble naturally occuring product, no refineing necessary, so very cheap.

A quick touch up with 320 paper to remove any small bits of paint left behind, a wipe over with thinners or prepwash, and you are ready to begin the painting process.

cheers Chuck.

[o_man_ra23]

The issue I have with sodablasting are the reports of it leaving a residual chemical on the metal surface to prevent immediate rusting. If this can be removed with simple 320 grit white, then for areas that are accessible to sandpaper, it's a winner.

["Z" UTE]

Owen, neutralize the soda residue with a mixture of vinegar and water. Rinse with a mix of sugar soap and water, force air dry with compressed air. Start your painting procedure.

cheers Chuck.

[K.Spencer]

Hey guys

Finished painting my car, was long and slow process! but worth it.
Wanted to know how long I should wait till i start polishing and whats the best process?

here some pics for all you
30092010.jpg
DSC00045.jpg

Cheers

[o_man_ra23]

What type of paint did you use?? Acrylic, 2k, Enamel??

[twentyEight]

I'd put money on it that it was Acrylic from that 2nd photo.

["Z" UTE]

K.Spencer, give it a couple of days exposure to the sunlight, UV is required to totally cure paintwork. Anytime after 5 days should be fine to attack the paint.

Small block of wood about the size of a matchbox, some 2000 wet and dry paper, a trigger spray bottle with a mix of water and car wash. Sand an area about the size of an A4 sheet of paper at a time. When that is nice and flat, move on to the next section. A rubber squeege can bne used to wipe the water slurry off the job to check your progress. Buff using a buffing pad and a variable speed buffing machine keep the speed down around setting 3. Your choice of compound, but I use JUICE. Change pads and use swirl remover. Clean off all buffing residue, and apply a sealer and glaze. You can then apply your choice of wax. Use microfibre cloths to buff to a brilliant shine. Congrats on having the balls to do the paint job

cheers Chuck.

[K.Spencer]

Yea its 3m Acrylic Gloss white from supershit.
Pretty much its a whole supercheap job , 2hp Diret compressor and my 2 guns from them ( Got that for $160 ) and Paint , Primer , Paint and Gloss ( $300 )
Will hand sand it because i have heard to many horror storys about buffing machines.

[o_man_ra23]

Something I have noted lately with my supershit gun is that the chrome plating is flaking off some components, and there is rust forming on the outside of the spray seat (note this rust is not affecting the spray at this time). I think I am getting my $40 worth out of it, however it definitely isn't a long term gun.

[K.Spencer]

Very true o man, was on special and was a once off job but definentialy got my moneys worth out of it. still gave it a thorough cleaning after use so we'll see how long it lasts!

["Z" UTE]

Will hand sand it because i have heard to many horror storys about buffing machines.

After wet sanding with the 2000, you will still have to compound the surface, hand compounding is so labour intensive.

The horror stories come about due to the use of a lambswool buffing pad in the hands of an inexperienced operator. SupaCrap sell a buffer for about $70.00, I have done dozens of cars with one, before graduating to a much larger machine.

Simple solution is to use the foam buffing pads, hard white/pink/yellow for compounding, and the very soft black pad for swirl removal.

The trick to eliminating damage is to make sure the pad edge never rotates towards the exposed edge of a panel. For example on a bootlid, the pad rotates clockwise, so use the front or toe of the pad for a right hand panel edge, and use the heel or rear of the pad for a left hand edge.

cheers Chuck.

[1JZ-Rolla]

After completing repairs on my guard, today I shot a few coats of high build acrylic primer.

The product I used is from Spartan, can be thinned down to simply use as a primer/surfacer, but recommends using it straight from the can for high fill applications.

I shot it with a 2.5mm fluid tip, after stirring the can for ages, and filtering into the gun's cup. Set 45psi on a 9 metre hose, and tested to find very light coverage, and poor atomisation. Increased the volume of fluid (coverage problem solved) and correspondingly had to increase the air pressure to 55psi to get a reasonable fan.

Now to be honest, it was probably a little bit hot this afternoon to be spraying, and this was likely to contribute to the problem I had, but what are your thoughts about ending up with a very textured finish on the panel? Not so much like a rough surface from paint drying before transferring to the panel, or too much air, more like an orange peel effect with the finished primer?

I ended up giving it a bit longer to flash-off between coats, cause I was concerned that it might not release enough of the solvents and end up with bubbles after drying.

Any comments welcome please, i've never used a high-fill primer from the gun before, only ever shitty pressure packs, but as it turns out, those pressure packs didn't shoot so bad after all

[o_man_ra23]

What type of gun are you using?? A gravity feed gun only needs about 20 or so psi of pressure, running 45psi will make you shoot like a 15 year old with a Picture mag.

[1JZ-Rolla]

For primer I just use a Trade Quip gravity fed gun, the kit that comes with 1.4, 1.8 & 2.5mm fluid tips.

What gun are you using that you can shoot at only 20psi inlet pressure?

["Z" UTE]

1JZ-Rolla, you are certainly on the right track. The Spartan primer/filler is very common in the spray shops around Canberra. Getting orange peel with the pressures you have used indicates that the paint was a tad thick. To get a good final coat of primer /filler, thin the last coat down, this will allow the paint to flow out leaving the surface a lot smoother. The type of thinners also has a huge effect. I only use general purpose thinners for gun cleaning. I use a multimidway thinners for primer, and 2pak reducer as my thinners in top coat, be they acrylic or 2pak.

cheers Chuck.