The Spray Painting Thread

["Z" UTE]

Hey guys, can i use metho spirits or must I use was + grease remover on the car before priming?

Metho dries extremely rapidly, and can cause water vapour to condense on the job. This is highly undesireable on a primed surface. Just buy some wax and grease remover, it is not overly expensive, a litre will do 2 cars.

cheers Chuck.

[H1TMAN]

Thanks Chuck!

["Z" UTE]

Hi Guys.

I'm spray painting a plastic strip on my car and got a few questions.

1. I'm applying an adhesion premoter first. Does the colour coat require a flex agent added, or not needed since I have allready sprayed on an adhesion premoter?

2. Is this process ok that im using so far?

1. Sand old paint off with wet/dry paper 300 grit (Any problem with using 300 instead of 600 or finer?)
2. Wax/Grease remover to clean it up before paint
3. Adhesion premoter 2 coats, 10 minutes between coats to dry
4. Paint, 3 Coats I'm using Acryllic Enamel, 10 minutes between each coat
5. Allow 24 hours before driving car.

Thanks, is there anything I missed out?

Also I went and got the paint matched, but the paint seems a bit off, its similar but you can notice its a different colour by looking at the strip next to the painted one. Is it normal when getting paint matched to be off, or should it be pretty much spot on as the paint card the guy put next to the strip was exactly the same, but the paint he made up was different?

Thanks.

Sorry I missed this one mate.

Most automotive paints are quite flexible but check with your paint supplier, just remember if the part does not normally flex, then the standard paint should work out ok.

I use plastic primer, it is available in spray can or bulk. 320/360 for forming shapeing bog or knocking back hi fill. 800 wet and dry before applying primer or colour coat. Any finer than 800 and the paint may not stick, any coarser and the sanding marks will show through the paint layers.

Your flash times between coats may be shorter or longer than 10 minutes depending on the amount of material you have applied, temperature humidity etc. Look for a distinct colour change/reflectivity change, this will tell you when the previous layer has flashed off.

Mixed paint colours should match the colour card, however if the colour card has been exposed to too much light the card may have faded, it really depends on how well the colour cards are stored.

The colour is normally made up of a base and tinter with additional tinters added in small quantities. If the formula is correct then the match should be good. Do not forget that the added tinters will settle to the bottom of the can. Mix the paint with a broad paddle, scrapeing in the corners and the bottom of the can, lifting the paint higher into the can. Might take ten minutes to get all the tinters incorporated, then check your paint against the original.

Spray a test piece, if the colour matches go for it. If not go back to your paint man, with the paint, the card and your test piece. If he knows what he is doing he can fix it. BUT this process is normally the domain of the painter, who will have a full tinters sytem available to him in his spray booth.

So called matched colours have caused me many headaches over the years. A few grams too many or too few of a particular tint can and will change a colour.


cheers Chuck.

[trd_st184]

I spoke to a respray shop down the road and he commented that the quality of the gun isn't all that crucial, as long as you are using the right jet sizes you should be able to get the same result.

He mentioned the reason u spend more on a gun is because the quality of parts will last you longer than a few spray jobs.

What are ur comments on this?

["Z" UTE]

I spoke to a respray shop down the road and he commented that the quality of the gun isn't all that crucial, as long as you are using the right jet sizes you should be able to get the same result.

He mentioned the reason u spend more on a gun is because the quality of parts will last you longer than a few spray jobs.

What are ur comments on this?

Probably right, I have been using a couple of guns for the past 20 years, and they were mid range price. Not Supa Crap specials, but a little better. Bought them at my local auto paint store. Still going strong, although my very first gun has now been relegated to primer duties due to a strange spray pattern. Probably a blockage that the ultrasonic cleaner will nor clear.


cheers Chuck.

[o_man_ra23]

The $85 gun that i have certainly didn't stand the test of time. It was fairly good to work with for the first 6 months/year, but after that it has gone down hill. It now leaks out the nozzle, the plastic feeder lid has cracked, etc etc. Like Chuck, this one will be relegated to primer, and I'll buy a new better one.

[trd_st184]

Yea thats true, i've had some good luck in the past with more cheaper brands but no doubt like anything they aren't designed to last.

In comparision to cars though even the best can fail.

["Z" UTE]

My oldest gun a suction pot type still works great, cost me about $50.00 like 30 years ago! No need to use it for paint these days, so I use it filled with metho and talcum powder to find leaks.
Simply spray all the door, window and boot seals with the mix, it dries real quick leaving a film of talcum powder. You then hose the car down, wander away for a coffe break, come back and look for areas where the talcum powder has washed off, thats your leak point! I just love a watertight car.

cheers Chuck.

[hamgatan]

ok so i laid down the colour on my bumpers last night and it looked smick.

went to lay the clear down this morning and then it looked even more smick..

but an hour later i started to get microscopic bubbles appearing in the clear.. at first i thought it was thinners evaporating through the clear, but then i realised it wasnt passing through at all.. so now its hardened and set and unfortunately i have to rub the clear back and do it again now.

what am i doing wrong that the clear was bubbling?

[trd_st184]

ok so i laid down the colour on my bumpers last night and it looked smick.

went to lay the clear down this morning and then it looked even more smick..

but an hour later i started to get microscopic bubbles appearing in the clear.. at first i thought it was thinners evaporating through the clear, but then i realised it wasnt passing through at all.. so now its hardened and set and unfortunately i have to rub the clear back and do it again now.

what am i doing wrong that the clear was bubbling?

Dust or contamination on the paint surface? Unless the paint coat under hadn't dried properly?

["Z" UTE]

ok so i laid down the colour on my bumpers last night and it looked smick.

went to lay the clear down this morning and then it looked even more smick..

but an hour later i started to get microscopic bubbles appearing in the clear.. at first i thought it was thinners evaporating through the clear, but then i realised it wasnt passing through at all.. so now its hardened and set and unfortunately i have to rub the clear back and do it again now.

what am i doing wrong that the clear was bubbling?

Mate, this is known as solvent popping, the thinners are 'boiling off" but as the top surface has already dried, the gases have no escape route. Cause, is too many layers of clear applied in quick succession, or your paint/clear is too thick.

You will have to sand it back and try again. I would adjust the thinning ratio, and if you are painting outside, shift the panel/car into a shaded area.

You have also had some really hot days in Perth just recently, was it on one of the 40 degree days you applied the clear. If so that is partly to blame as the top strata would have dried really quickly trapping the thinners. The ideal painting temp is about 20-28 degrees. In a booth the temp is set high to warm the metal, turned off while spraying, then tuned on again after the final coat is applied to effectively bake the paint on.

cheers Chuck.

[hamgatan]

I think you're on the money there Chuck..

I did it early in the morning in the open air when the temp was sub 30 (7am).. but the temp rose very quickly and as the bumpers were in direct sunlight it copped a lot of heat very quickly. I think i whacked on the clear too quick thats why.

I had the same issue with the bonnet. dropped the paint on fine, but when i got to the clear i did the lightest sprayover, and noticed it started to go white the second it touched the surface.. i'm assuming that its coz the panel was way too hot and it was drying on contact..?

When you say sand it back though.. you mean only the clear layers right? (not the colour?)

Chris

["Z" UTE]

Chris, yeah you have explained it well. Too bloody hot, and the top layer has sealed in the thinners preventing them from evaporating. A rub back with 800, make sure you remove all the old bubbles. Recoat with clear, also remember to do a real thin mix (20% paint -80% thinners) for the final coat of clear. This levels the clear, and brings on a nice gloss. This step will save you heaps of buffing time. Remember not too heavy with this last application, or you will have run city.

cheers Chuck.

[Gibbon]

So I'm about to have a go at painting my MA61 - when I noticed this





Is it something that could be ground out and then rust treated? I've never done any bodywork before so I'm learning as I go.

["Z" UTE]

A rather bad starting point for a beginner I am afraid. The screen would have to be pulled out, the rust cut out, and a new section of metal welded in. The reason I say this, is that you will more than likely find a whole lot more rust under the screen.

cheers Chuck.