The Spray Painting Thread

["Z" UTE]

DrNick, the PPG stuff is 2 part. From what you are saying, I think you probably need to feather the deges away from the hole. ie, create a shallow ramp, instead of a near 90deg joint. This way you can fill past that problematic edge. Even a stone chip has to be addressed this way.

Back off on the sanding pressure, and let the grit do the work.

cheers Chuck.

[RdS]

seems to be the best place to write this... so..

..i had my first go at painting with a gun today. always just done touchups with rattlecans, and had no trouble. but doing bigger things needs more paint, and it is just cheaper and easier to use a gun for that.
have gathered all the shit i need to prime and paint, and thought it was worth a crack. have a cheap suction feed gun i was using for priming, and bought a new grav feed with a smaller tip to paint with.
been sanding all the shit smooth for the last week, prepsol'd it all, and layed it out to be painted. all's sweet.
since its a plastic lip and side-skirts, i bought a tin of K&H plasti-prime. took the lid of the tin - and god its thick! looked like some sort of goo. grabbed a screwdriver and stirred it up for a couple minutes... looked better.
poured 200ml's into a measuring cup, then about 170ml's of K&H general purpose thinners... since thats what it said to use at .5 to 1:1 ratio. stirred it up.. and now it seemed more like a paint than a goo.
the gun i used is a supershit auto spec 'scorpion' suction feed gun. read the instructions, and figured which knobs adjust the overall air it uses, how much paint to air, and the adjustment of spray pattern.
poured the paint into the gun's tin, plugged it into the compressor at just over 3bar (~40-50psi), and away i went:
BUT, at first it seemed to be spraying waaaay to fast... so i turned the pressure down on the gun. seemed better, so i started painting. problem i found was that it was just to airy for the paint. i adjusted the paint-air ratio knob untill it popped off the back of the gun. was shit.
so the paint is very very rough.. used it all up doing this, mixed up a second batch of the same, and kept going. then i realized that the paint was practically coming out of the gun like a spray on carpet. spraying it into the air made it look like streamers of some shitty fur.
now this is where i was left very dissapointed and wondering where i fucekd up.
- why is the paint coming out so dry? does it seem this way just because im not spraying it on thick enough?? is it too much overspray making it seem like its coming out rough and dry?
- why was the paint spraying out so badly.. like fluffy streamers of somesort...
i decided to stop it all there, before i sprayed on more shit paint id have to remove, or waste any more paint.
so i started to clean it up. took the tin off the gun and straight away realzed that the paint was drying in there. it was like leather.
- had i not mixed the paint right? or had i just left the gun too long and let it dry?
it almost seems as though it had seperated in the tin, and i was only spraying thinners from the second batch..

i guess now im going to have to sand smooth all the paint ive put on, and clean up any mistakes. im going to give it another shot in the next few days, so any help would be GREAT. please? ..i hope i explained the problems well enough.

[ian]

it sounds like its to thick
what ratio did you thin it down
it also sounds like you are trying to put spray putty through a top coat gun ,to spray on putty /or high fill you need a proper putty gun ,with one of those you can put on high fill almost as flat as top coat,
at a pinch, you can brush on spray putty
it means a lot more work, but it does work
ian

[RdS]

i dont think its a spray putty? as far as i knew, its just a primer with a flex additive in it for helping the paint stick to plastics?
the gun is a suction feed gun with a 2mm tip i think?? i was told it would be good for primers?

i thinned it down the .5 to 1 to 1 ratio like it said on the tin.. i did about .75:1
should i think it more? its seemed like it didnt really want to mix with the thinners, but that was the thinners it said to use on the paint.

[DrNick]

There are many people on here who know heaps more about painting that I do. But to me it really sounds too thick.
I use a 2mm tip for primer as well and with the primer-filler it is 1 part primer to 1.5 parts thinners. If I want to paint primer with my smaller touchup gun then it wouldnt spray at that thickness so I would thin it down a bit more.
I suggest you just go by 'feel' - start with 1:1 ratio and see how it sprays, if needed then tip it out and thin it a bit more. Just get an old plastic crate or something to practice on.
Good luck

[RdS]

im thinking now it was a bit too thick. didnt seem so in the cup, so maybe i hadnt mixed it well enough.

would this be the reason for it coming out of the gun like some sort of fluff?

[DrNick]

Yeah that would make it come out funny. Make sure you stir the paint really well also , i used to use a screwdriver but it doesnt really do a good job so i went and got a steel ruler from supercheap and use that as a paint stirrer as it really gives it a good mixing.

[RdS]

ah.. thatd be a major problem! im using a thin ass screwdriver to mix it. seemed like it wasnt doing a good job..!

["Z" UTE]

Rds, first problem is stirring with a screwdriver. You need a flat broad blade that you physically lift the heavy paint solids of the bottom of the can with. Worst case scenario pinch mums wooden spoon outa the kitchen. The paint is made up of various solids and fluids, you have to mix them thoroughly to get a consistent mix.

The cobweb effect is great if that is what you are aiming for, but that basically means the mix is way too thick and you have adjusted the air flow so far off, that it is out of the equation.

Mixing ratios are a guide, you have to adjust for temperature, and the possibility that the paint is old stock. When mixed properly the paint should be the consistency of somewhere between engine oil and petrol, about midway between. Thinners need to added a little bit at a time and then thoroughly mixed before adding the next small batch of thinners, and continueing to mix. That will take a bit of time, but well worth the effort.

For what it is worth, I threw out my suction pot spray gun 10 years ago, and only use the gravity feed guns.

cheers Chuck.

[RdS]

thanks heaps you lot..
gonna give it another shot tomorrow or the day after i hope. keen for another try now.
i think the paint fumes were going to my head.. as its obvious now it wasnt stirred well enough. i just stirred it for ages and figured itl be right, but it did seem very thin at the top. :$

ill use a metal ruler i have next time.. or nick the wooden spoon! i actually nabbed mums clothes airer to hold up the bumper im painting! hopefully i can use it again before she notices grey paint on it.

[o_man_ra23]

I had this happen to me with some Pro-Tec acrylic topcoat once. Made a mess of the engine bay before I realised what I did wrong

Basically, the little air vent at the top of the pot got clogged (same type of super shit suction feed gun, probably same gun but different brand name, I think mine was Super Works Air branded)

So yeah, thinning did shit all, adjusting air did shit all, and once I unclogged it, the paint just came out like magic!! Well, magic compared to what it was, overall it was still a pathetic job, but back then I couldn't afford a decent gun

So yeah, check that nothing is clogged before you go too far. The bit I am talking about goes to the little hose at the top. Check both nipples for cloggage.

[ian]

what you really need is a stirring pot a
you can buy them in the $2 type shops
a half decent respirator some paint filters gun wash to soak the spray gun bits in then get a paint mixer to put in an electric drill
mix up the paint maybe a tad thick ,put a little in the gun
then try it on an old guard and gradually try thinner mixes , until you find one that suits
and for the stirring stick all good auto paint shops have the mixing ratio printed on them , they are a very handy tool ,it can open stubbies as well
i have misplaced my stirring mixing ratio stick maybe someone else has one that they can post up

[RdS]

thanks for the tips.

also, sounds like i should just use my grav-feed gun. it came with some larger tips in the box... so i may aswell. hope i dont wreck it though..

["Z" UTE]

thanks for the tips.

also, sounds like i should just use my grav-feed gun. it came with some larger tips in the box... so i may aswell. hope i dont wreck it though..

A paint gun is only a tool, but it is one that deserves to be looked after. You must strip the gun down to its component parts when cleaning. Simply running some clean thinners or gunwash through the gun does not cut the mustard. You probably got the tools and the cleaning bits in the box when you bought the gun.

My cleaning regime that has kept my gravity guns spot on for lotsa years.
Takes about 10 minutes but well worth the effort.

Drain all paint, place some thinners in the pot, and use an artists brush to clean the inside of the pot. Run some of those thinners through the nozzle, and dump the remainder into a containter. I use an old 4 litre thinners can, with about 25mm of thinners/gunwash in the can. Remove the air cap, the needle and then the nozzle. Wipe the needle down with a cloth damped in thinners. Wash the air cap and the nozzle in the thinners using a brush.
Remove dry and put aside those bits. Use the bottle brush to clean the bottom threaded portion of the cup, and the air valve on the lid. Again with the artists brush, clean the inside of the pot. Use a rag damped with thinners to final clean the inside and outside of the pot. Use the bottle brush to clean the inside of the large holes in the gun. DO NOT immerse the gun in thinners as this will dry out the "O" ring seals., just use the cloth with thinners to wipe all the old paint and overspray/backspray off.

Reassemble gun, apply a "small" amount of vaseline to the brass slide on the needle.

Quarter fill the pot with clean thinners, attach an air line, cover the centre orifice with a clean cloth and pull the trigger, this forces thinners out through the air holes. Cover each air hole alternately and blast the thinners through the open air holes This blocking and opening also forces the thinners and air back through the gun and into the pot, and will dislodge any crap that you have missed. Dispose of the remaining dirty thinners, and put you gun away with the knowlede that next time you need to use it, it will work perfectly.

Cheers Chuck.

[rolleraction]

Well said Chuck.