The Spray Painting Thread

["Z" UTE]

By all means use a slide hammer, but do not put a hole in the car. Use what is known as an "easybeat", there are various models. Some weld a brass ring onto the metal, you then use a slide hammer to pull the dent. Others use a brass spike which is also welded on, but the easybeat alos acts as the slide hammer. Please try to avoid putting any holes in panels, as these ineviatably reappear as rust.

If you must put a hole in the panel for the slide hammer, it should be welded, cleaned, phosphated, primed and painted on both sides.

A mate of mine whose son is a panel beater has just suggested that I use "silicon bronze" wire in my mig for panel repairs. The silicon bronze wire has a lower melting temp, less panel warpage, and is a lot softer, facilitating easier grinding. Will give it a try, but tyh wire is 4 times as exy as standard mig wire.


cheers Chuck.

[Z2TT]

Thanks.

So next time, Should I spray a coat of thinners over the area after the final layer of basecoat is on? and then wait for it to flash off.... do my clearcoats and then do the same after the final layer of clear is on?

Should I wait for the base and to fully flash off before i go over it with thinners, same goes for clear?

[ian]

another handy hint is, heat the spraycan
put the can in very hot water for 5min
this thins the paint a bit and it flows better, also the increased temp gives the spray can more pressure
i must point ,out . hot water only , i have seen a nuffy try and heat it in the oven ,his mum was not pleased
with the colored oven when it exploded

[kremsra28]

If i used a slide hammer to take a dent out, whats the best way to fill that hole again? I saw people use quiksteel before. I want it to be as similar to the original metal as possible.

a quick dodgy way is to try to keep the hole as small as possibly then get a self tapping screw thats bigger than the hole, screw it in and the just gring the head donw so that the thread fills the hole, as i said, its a quick and DODGY way but will work fine if you use kahglass over the repair area 1st before normal filler, the khglass will hold the screw thread in better and stronger.

preferebly, i would weld it over, do it properly the 1st time, then there wont be anything to worry bout.

or you could just use kahglass to fill the hole if it is small and you dont have welder or grinder to grind head off screw.

krem

["Z" UTE]

Z2TT, the coat of thinners is used primarily to blend the edges of the newly applied paint/clear to the existing paintwork.

The coat of thinners is normally only applied to the clear coat after it has flashed off, not fully dried, or dry to touch, just when the wetness disapperas from the surface.

That coat of thinners could also help to "lay" the paint down flatter, it is normally only done with paint applied with a spray gun.

I for one can not guarantee that the thinners will not react with your spray can applied paint, never having attempted it.

ian, I always place my cans in the sun for 10 minutes or so before using them, especially in Canberra's colder months, about 11 of them. os as you suggested warm them in some hot water. I purchased an old pie oven for $20.00 from a canteen at a school that was closing down, works a treat for baking spray can enamel!

Funniest thing that I saw recently was an advert from my powder coat supplier, a liquid additive (thinners) for powder coat, "touch up damaged powder coat with your spray gun" Doh, looks like paint to me.

cheers Chuck.

[Z2TT]

Thanks chuck, well Soarer is done and am quite happy with result.

Yeah next time i would use a spray gun if i want to use thinners to blend in. My Question is why is it only done on the clearcoat, why shouldn't you do it to blend the basecoat in aswell with spraying thinners for a better result?

["Z" UTE]

The blending is only required at the edge where the final coat overlaps onto the original coat.

cheers Chuck.

[Z2TT]

Thanks, I was just under the impression that it would help also to blend the basecoat with thinner so you cant like notice the gradient change under the clear where the new basecoat meets the old paint colour.

What types of paints I'm wondering need to be baked, I understand this is done in booths yes?
Since you said that some paints crack when they were force dried, but i'm wondering isn't that what should be done on some types of paints? I take it Acrillic you don't bake, what other types of paints is there that do need to bake and what does the baking do, helps it cure quicker? or is it a necessary step and must be done?

Thanks.

["Z" UTE]

Spray booths are used to heat the car to start with, the heat is turned off whilst spraying, then the heat is turned on again after the last coat of paint/clear has benn applied. The build up of heat is not rapid, therfore the paint is not force dried but baked slowly, ensuring all the solvents are evaporated.

Enamel was the most common paint type some years back, and needed to be baked for quite some hours. Acrylic and 2pac paints are also baked, but this is primarily to speed the flow of cars through the repair shop.

Some 2pacs are low bake others are high bake, referring to the temperatures that each must be baked at.

Yes 2 pac is a catalyst hardened paint, but it still contains volatile solvents and in some cases added thinners that need time to evaporate. One 2pac painter I know uses a fast hardener, and about 20 thinners, the recommended thinners is 10%. This guys glosss off the gun is great, as the extra thinners allows the paint to "flow out" and become extremely level, almost eliminating the orange peel effect.

cheers Chuck

[DrNick]

The "halo" you are getting at the edge is not removable. To prevent this in future, you must spray a light coat of thinners over the painted area, to blend the new paint/clear to the old, but it must be done during the painting process, not anytime later. Buffing will never eliminate the halo, but it may hide it for 6 months. Buff and wax it again when it reappears.

Is there any way of avoiding this halo when using acrylic lacquer to spot repair a panel that has the factory 2 pac paint?

I'm fine if the panel was painted in acrylic, but never been able to get it just right if the paint underneath is still the factory stuff.

["Z" UTE]

DrNick, you may be able to reduce the halo effect if you paint only to the edges of the underlying sanded paint. I have tried many times and this is only about 50% effective. There is very little margin for error, if you do not coat the sanded paint you are stuffed, so a little more in this case really is better.

If you are close to a panel edge, or a swage line, take the new paint right to that edge.

Even blowing a coat of 2pac, on day old 2pac that needs a quck repair will result in the halo. Highly visible when wet sanding, but becomes almost invisible after buffing, but I am sure it will reappear before the next buff job is due.

cheers Chuck.

[Z2TT]

Hi,

Why will the halo re-appear with time? Mine is not very visible but visible a bit under certain light. So is it just going to get more and more visible over time and why?

Also when doing touch ups on rusted areas, like on the bottom of my door i have like a straight line of rust. if I sand it off and it gets down to the metal which it would, can I apply some paint with a brush over the metal or will there be problems, what way should it be done?

My plan was to thin some acrillic down and use a paintbrush to apply it, would that work or will it rust again?

["Z" UTE]

The halo is an area of incomplete paint coverage, ie, the paint is not uniform, thin in some areas thick in others an zero in other places. Any paint that is thin when exposed to the elements will oxidise hence the reappearnace, particularly when the wax has worn off with the six months of washing the car, in fact paint starts to oxidise as soon as it cures, so buffing and waxing is essential. The wax reduces the oxidisation as it fills the pores of the paint.

Any rust will have to be mechanically removed, wire brush, sandpaper etc. BUT even when you see shiny metal, there will be microscopic rust spots in that area, these must be treated with a rust converter. So treat the entire bare metal area with the conveter. The converter chemically changes the ferrous oxide back into steel, you then prime the area, and repaint. Any short cuts here and the rust will re appear, yes you can brush the paint on, but the finish will be a brush finish. You certainly would not need to thin the acrylic, unless you want to spend 3 days doing the paint repair.

You should also have a look inside the door to establish if the rust is purely external or emmanating from the interior of the door. If you have rust inside, mechanically remove it, treat with rust converter, and give it a quick shot of paint, then shoot some cavity wax over the area to keep any moisture out.

cheers Chuck.

[o_man_ra23]

Have ordered my POR15 paint, so should be applying it next week, assuming I get my rust repair done in time, then I can put the car back on her belly...

[Z2TT]

Thanks chuck.

My acrylic though is too thick to be applied with a brush, it just sticks to the brush without using any thinner.

Thing is the area is so small it's not worth to respray it, mask etc. Am not fussed with a brush finish as it is literally at the bottom of the door.

so can the primer be brushed on or must it be sprayed? do I need a special etch primer and then have to put normal primer on, then paint?

Am told that etch primer protects against rust and makes a barrier and must be used on metal.