The Spray Painting Thread

[jb_22]

oh actually, had another problem... the colour turned out kinda creamy, and not the same as it was before... I assume this is due to old paint? paint not mixed properly in the tin or something, any ideas? Doesn't really matter too much now, but would be good for future reference.

The creamy colour is usually due to high humidity. You might find that spraying on an overcast day or after it's been raining will cause the paint or lacquer to become creamy.

[JZA70R_92]

Hi guys and gals

Gonna be spraying my car in the next week or so. Ruby pearl black 206. I was planning to spray it this way.......some parts are bare metal at the moment so planned to do bog work, primer(with etch in it), satin black as 1st layer then the rest ruby black and clear coat??? that sound good?

[o_man_ra23]

Make sure your primer has an even colour the whole way around the car with no shades coming through from bog/previous paint and you shouldn't have a drama. Getting to the stage of the primer being all an even colour is 90% of the work, and will have about a 95% effect on the final product.

[JZA70R_92]

so adding matt black then ruby pearl is ok? or should I just spray primer grey and then colour then clear.

[o_man_ra23]

Primer grey, then you can go matt black followed by the rest of your colouring. That would give a better depth of colour and a darker black than going straight over primer. The primer will block out the below imperfections and give you a blank canvass so to speak, where the black may show through the lower layers as dirty looking marks which will forever haunt you.

Putting extra layers of paint on won't damage the finish, not putting enough will though. Also, let the primer settle for 2 weeks under cover (try not to get gecko shit, dust etc on it, but be wary of sitting a cover directly on the primer) so that the primer has a chance to settle, shrink and do all sorts of other wierd shit, then do a final light sand over the panels before painting to flatten it out. Always use a guide coat and a large sanding board when sanding.

[JZA70R_92]

cool thanks for the info most likely using protec gear! hope my 2hp comp can handle it hahhaa painting a rear panel, bumper and 1 front panel and roof....

[o_man_ra23]

Roof will be the hard part. Can you borrow a real compressor of somebody?? The little ones just don't have a big enough pump to keep up.

EDIT: I have used the ProTec gear before on a small 2.5hp direct drive single piston compressor. There is no reason you can't get a good finish with a setup like that.

[JZA70R_92]

it does 172L per minute it did an ok job on my other car. what I found though is it ran almost non stop.....

[TERRA Operative]

What size compressor should I use with my Devilbiss Gti Pro?

[o_man_ra23]

No matter what gun I have used, my 2.5hp Puma belt driven twin piston pump has never had a drama keeping up. Running all the time isn't an issue, so long as the pump can keep the pressure in the tank higher than the pressure you require coming out. So if you have your pressure regulator set at 42psi, and your pump can maintain a tank pressure of 43psi, it doesn't matter that it runs constantly (also as long as it keeps itself cool enough).

TERRA, when it comes to buying a compressor, bigger is better. Buy the biggest you can which will run on the power supply you have (2.5hp is normally the max for a 10A plug). Or, alternately, go petrol powered, then you are limited by your transport capabilities, just need to plumb the exhaust out of your shed and make sure it doesn't leak (or better still, have the compressor in a lean-too outside the shed and plumb the air hose in).

[JZA70R_92]

done some reasearch and with a 2HP jobbie I can use a low pressure gun as HLVP gun requires more pressure...confused lol

[o_man_ra23]

As pressure increases, flow volume available decreases. And it's an exponential curve, meaning that an increase in pressure by 1 unit at low pressure causes a lower drop in flow volume than an increase in pressure by 1 unit at high pressure. This is the pump dynamics and the rate at which it drops off is determined by how good your pump is.

A 2.5hp compressor will run without straining in a situation where a 2hp will struggle. And to top it off, the 2hp will heat the air extra, which will play havoc with the humidity in your line, and the paint you are laying on.

Once again, bigger is better.

[JZA70R_92]

all is good just recalled I have a $100 bunnings voucher will use that plus cash to get a proper one been quoted $238 for a 2.5hp 40 litre tank belt driver compressor......

2HP = Dead when it runs sounds like ball bearings getting shaken up in a paint tin

[o_man_ra23]

Yeah, a $238 compressor should be ok to paint with, wouldn't expect more than 5 years out of it if you use it regularly, but should work fine till then.

["Z" UTE]

Hi guys and gals

Gonna be spraying my car in the next week or so. Ruby pearl black 206. I was planning to spray it this way.......some parts are bare metal at the moment so planned to do bog work, primer(with etch in it), satin black as 1st layer then the rest ruby black and clear coat??? that sound good?

Primetr with etch in it? No mate what you need to do is etch prime the bare metal, then primer the whole car. Mixing the 2 will be a cluster #@$@#@.

After primer/high fill, spray on a mist coat of chassis black, that will be your guide coat. Sand all of the guide coat off, as this will show all the little imperfections. Your high spots will rib off straight away, and anything deeper will stay black. You may have to fill some of the real low spots, spot prime and re rub.

If your paint manufacturer recommends a dark primer or base coat use it.

If your primer coat is not exceptionally thick, you can prime and sand one day and colour and clear the next. If you leave the primer for more than a week you will have to re prime and sand again. Lets face it properly applied primer is dry and sandable within 2 hours.

Crows foot and stretching of the paint comes down to the layers of paint drying at different rates. So the more you can do in one day the better. Paint shops use what is called a "wet on wet" method. Primer is applied and then levelled (guide coat), coats of colour are then applied, allowing flash off time between each coat, then the clear coats are applied, using the applicable flash off times between each of those coats.
This method ensures that there are no dry boundaries between the coats.

cheers Chuck.