The Spray Painting Thread

[o_man_ra23]

Salt is harmful in high doses though... never underestimate a chemical's ability to come back and bite you in the arse when you are talking about inhalation or ingestion. Some chemicals are pretty deadly just with touching.

[dougTA22]

Dear spraypainting gods,
I have a bit of a problem that i'm hoping you can help me with.

I bought a lovely old celica that i would one day like to give a full bare metal respray, but due to a severe lack of funds/time/space i can't do it at the moment.

The problem is that a couple of reasonably large rust spots have started to come up through the paint The previous owner has painted a two pack metallic (black with a gold flech though it, apparently it's called holden black) over a couple of old layers of paint on there. Over the weekend my old man got a bit grinder happy and ground out the main rust spots before i got a chance to enquire about what direction i should go...

My questions is: what can i do in terms of painting that wont look too shit? How do i go about blending in the fresh paint to the old paint so it doesn't stick out like dogs balls? I've read through the whole thread, and there is alot of great info in there, but it was mostly about full resprays, not so much about touch ups.

The full respray thing will (hopefully) be happening in around a year after i've saved up some cash, so it doesn't need to a perfect last forever type fix, but i would like to do it reasonably well. I have a little bit of experience doing bodywork and metalwork, but i know sweet FA about paint, so any tips would be much appreciated.

Cheers,
Doug

[CheeseBiscuits]

Hi Doug,

Not a god here, but an amateur like your self.


My understanding of Pearl paint is that you'll pretty much have to re-do the entire thing for it to look good? (but I don't know so, wait until the other guys comment! )

Do you already have spray gear? or or you planning on purchasing that later on? If not you could probably do some POR15. I hear that stuff comes out shiney and smooth off the brush. (again, could be a stupid idea, so let the experts comment, just an idea )

[DrNick]

Woo just tried out my new DeVilbiss HVLP gravity feed spray gun today. Its very different from my old cheapo star one, the fan is very even, and its easy to control the trigger whereas the other one was more on/off than anything else.

However I'm finding that the droplets of paint are bigger than I would like them to be. I dont know what could cause this, the panel looks quite orange peel like when I first spray it (due to the big droplets) but if i paint quite a wet coat then it flows together and turns out ok.

The manual says only 32psi is needed, but at 32psi it doesnt spray at all. I am running it at 45psi (or at least thats what the gauge on the handle of the gun is saying). If I go up a bit higher towards 50psi then I start to see more overspray (At 45psi there is practically none, its quite neat really).

Any suggestions for how to set up the gun to get nicer atomization?

[ian]

with the devilbliss you can get a smaller needle tip combo
what needle and tip are you using now

[o_man_ra23]

Doug, do you have the formula for the paint?? Or some of the actual paint?? You will need to also find out the brand of paint, as you will want the thinners to be as compatible as possible. If you can't replicate the colour properly, then you will have a very hard time stopping the repair from sticking out like dog's balls, especially with black.

[dougTA22]

Cheese biscuits: I do have access to painting gear, dad has done a bit of painting, but only in acrylic - he's never painted 2pac before so we don't really know where to start, apart from trying to find an iso free one. You have to use a 2pac filler too yeah? I would very much like to do a full respray, but it's a bit harder than impossible for me right now

Owen: I don't have any of the actual paint, but according to the previous owner it is apparently a standard paint colour, not custom mixed, so hopefully shouldn't be too hard to match colour wise. No idea about the brand though, but whatever i do end up getting i will be getting the right thinners for it. Would it be the end of the world if you touched up with a different brand to the original paint?

It doesn't need to be perfect. My old man wants to try and spray a black acrylic over it, so just about anything else that i can try will stick out less than his idea i think, as well as compatability issues between paint types.

Thanks,
Doug

[DrNick]

with the devilbliss you can get a smaller needle tip combo
what needle and tip are you using now

Its got a 1.5mm on there now. The star (suction feed) had a 2mm and atomized better but with HUGE clouds of overspray.The new one is a lot neater. I'm spraying acrylic.

["Z" UTE]

DrNick, sounds as though your new gun is working just fine for a 1.5mm tip. Use a 1.2mm for topcoats, and you will get better atomization of the paint, also try adding a little more thinners, to allow the paint to flow better.

DougTA22, not a god of spray painting, but have quite a few years experience. Apply a rust neutraliser to the ground out areas, or patch as required. A good acrylic primer filler will do nicely over the patch areas. Mask around the repairs, but make the masking at least 4 inches away from the edge of the repair. Spot prime the repair, but do not paint to the masking tape, ie. just cover the repair. Sand with 800wet. Spray colour,and clear again not out to the masking tape, otherwise you will have a lip to deal with. Final step remove the masking, and spray a very light coat of "thinners" around the repair, what this will do, is "meld" the overspray/thin paint edge into the original paint. The process is called blending.

You can repair a 2pak paint job with acrylic. If you are covering 2pak, it will depend on the age of the paint on the car, being a few years old you should not have too many drama's, as long as your primer properly covers the thinned edges of the the previous top coat. If the primer does not cover the sanded area fully, you will get frying at the edges where the acrylic topcoat penetrates the primer and reacts with the thin edges of the 2pak.

As a general rule, if the repared area will be larger than an A4 sheet of paper, you are advised to repaint the entire panel, otherwise the repair can be quite evident.

Hope this helps, cheers Chuck.

[o_man_ra23]

Doug, it isn't always imperitive to know the brand, however some brands don't react well with others due to the different chemistry. I would say if you don't know it, then give it a go anyways. What will happen if they don't match is you will get frying where the two brands don't like each other. The technique that Chuck has described requires the old clear and the new clear to be compatible at the very least to allow them to blend. In the majority of cases, this should occur without too much fuss.

If the colour is indeed off the shelf rather than custom mixed, then the best thing to do is get onto the old owner, and ask them if they have the colour code (from the firewall), make model and year of the vehicle the colour was knocked off from. If they know the make model and year, but not the colour code, then start hunting around used car lots to try and find the colour code, as this will give you the best chance of a good match.

It has been discussed in here before, but if you use acrylic primer under 2pak paint, you need to let the primer bleed out all its thinners before applying the 2pak over it, or it can make a mess of your final paint job. Can't be certain, but I would say that a couple of weeks should be enough time to settle the acrylic primer fully.

One more thing I will add, is that in some instances (especially when several layers of paint have been applied over the years), there will be a layer that your primer fries on. This will be evident as a big ring around the primer that looks fuzzy. If this happens, you will need to sand all the fried paint back off, and apply an isolator over the affected section. Bit of a pain, but you never know when somebody thought it a good idea to whack on some nitrocellulose or other such paint.

["Z" UTE]

It has been discussed in here before, but if you use acrylic primer under 2pak paint, you need to let the primer bleed out all its thinners before applying the 2pak over it, or it can make a mess of your final paint job. Can't be certain, but I would say that a couple of weeks should be enough time to settle the acrylic primer fully.

.

Or you can use 2pak thinners/reducer in the primer to eliminate that problem. Then normal flash off times apply.

cheers Chuck.

[o_man_ra23]

Isn't it more the quantity of thinners required for acrylic primer the issue with rest time for primer?? I know with the 2k priming I have been doing lately, a small splash is plenty for filling, and 25% caused the coats to become too thin to cover, where acrylic I was struggling to keep the paint wet at anything less than 50% thinners.

[dougTA22]

Thanks for the help guys, really appreciate it.

I spoke to the previous owner, all he knew was that it was from a holden range and recent - from a car sometime in the last 2 or 3 years. He said the paint shop he went to just called it holden black. I guess it's time to start going through some holden catalogues (i hoped never to utter those words...)

I'll try to find the proper paint code, and if not then i guess a black acrylic will do. They aren't very big repairs and it's not forever...

Cheers,
Doug

[MWP]

So whats the best way to go about doing a cut & polish?

My GT4's white paint has a film of brown crud embedded in the top layer of paint.
If i rub at a spot for ~10sec with a cutting compound the brown is removed and it bceomes clean white.
I cant imagine doing this for the whole car though, esp with a equally long polish & wax after.
It would take days and thats if my arms would last that long (which they wont).

Tools? Cutting / polishing products?

[o_man_ra23]

Doug, did the previous owner tell you which paint shop he went to?? If you know when the paint was applied, and the colour was from within 3 years of that time, then that helps your search. Again used car lots are your friend, find something which matches all the descriptions you have (ie black, holden, year range) and look up close to the paint, and compare it with the paint on your car (may have to use your memory). Find something which matches in darkness and fleck, then swipe the manufacturer plate details mentioned above, and go to your preferred paint shop. The base colour can probably be done in just about any brand, but so far the only cyanide free clear I have come across is Hi Chem.