The Spray Painting Thread

[joey]

I've got some small paint chips on the very edges of my driver door from my mum backing out the celica with the door open and clipping the brick wall on the side Its 2pac pearl paint... now would i be alright to just touch up the spots by brushing on the 2pac with a small brush? Would it stay on there fine? Reason i ask is because when i got my boot redone i had to get it baked in a kiln and what not for it to set....
Any advice is appreciated. Joey

[CheeseBiscuits]

Hi guys,

attempted some painting again today... no idea what I'm doing wrong.

either I'm just retarded or the guns I've tried to use are just crap (ebay guns) or my mixing skills are terrible and the ratio's are wrong.. I have no idea.

basically using acrylic with a 1.4mm HVLP gravity fed gun and no matter how I set the gun, it either barely comes out at all (as in after 10 passes it still looks like it hasn't been painted) or comes out like sandpaper.

What am I doing wrong?

conditions today were around 25ish, fairly dry. not too hot. The car was clean, had been washed extensively, then washed again with wax and grease remover. left overnight, then I used the compressor to blow any dust that had settled off.

So what are the likely causes for the paint to come out of the gun and turn into a sandpaper like texture on the car? Guns were cleaned before use and everything seemed okay. (I also test sprayed on some cardboard and and at first it came out a little rough, then it was okay, so i moved to the car and.. well.. yeah.

help please. at this rate, I might have to pay someone to do it for me... however no business' want to paint a car with out prepping it first -_-

[1JZ-Rolla]

what air pressure are you spraying at?

[Grega]

how did you mix your paint / ie: what ratio of paint to thinner
sounds too dry

i normally do 300 / 200 - 200 color, 300 thinner. works for me well...

["Z" UTE]

Sounds very much like the air inlet in the the little cap of the pot has a blockage. You are creating a vacuum in the pot. As 1JZ-Rolla has suggested your air pressure will be way too high if you are getting a sandpaper finish. Air pressure should be about 35-45psi with a hose length of 8-9metres from the compressor outlet. The longer the hose the greater the pressure drop.

cheers Chuck.

[willwal98]

Maybe your gun could do with a good clean. You can buy a little kit with some picks, bottle brush things spanners to help dismantle it.

like this one http://cgi.ebay.com.au/MASTER-SPRAY-...3A1|240%3A1318

[CheeseBiscuits]

not exactly sure what pressure, but at the tank it was a fair bit higher than 40psi, as I understand it drops.

Grega, not exactly sure what you mean by your ratio's. sorry.

i was doing as stated on the can 1 part paint, 1 and 1/2 parts thinners.

The cap on the pot sounds interesting... I can hear the paint moving around when I spray, like someone is blowing a straw into it. But from what I remember, there is no suction cap on this pot, so maybe its a design flaw that is screwing me up, haha.

will find my gun pressure gauge tomorrow and check the pressure, but I think it would be around 40psi.


cheers guys. Really frustrating spending so much time wet and dry sanding getting a smooth finish all around, to just have the paint come out like shit. -_-

[Steve M]

I've had it recommended to me that acrylic and in particular, metallic acrylic paints should not really be sprayed with a tip smaller that 1.8-2.0mm and that HVLP guns were not really suited to acrylic paints.due to the characteristics of the material.

Blowing bubbles would indicate a blockage somewhere that's forcing air into the wrong path. As was suggested above, make sure the gun is clean and that all the seals are functioning.

["Z" UTE]

SteveM, I beg to differ on the nozzle size. A 2mm nozzle is perfect for high fill primer. For colour coats and clear coats 1.2 or 1.4mm are the way to go, with either acrylic or 2Pak systems. Thats my experience over the past 15 years.

The major problems for a part time spray painter, are gun cleanliness, and establishing the correct thinning ratio. You really need to look at the ratios recommended by the manufacturer, and add a fudge factor because you are not in a the controlled environment of a booth.

cheers Chuck.

[CheeseBiscuits]

Yep found the blockage in the cup. the air hole was blocked.

Gave the gun another clean. Everything is absolutely clean. Will give it another go next time it's sunny.

I remember when I did the primer I had no problems, but I used a different gun/cup, so maybe that was the problem. we'll see.

[jb_22]

Hi, new on the Toymods thread, so I thought I'd make a contribution =D

I know it's not on direct topic, but it's panelbeating nonetheless. Awhile ago I had a fender bender with my old car (CC Lancer), and I posted my repairs & modifications up on EvoCoupe. I hope it comes in handy sometime! Any questions just ask

http://evocoupe.net/forum/viewtopic....beating#p34013

Cheers, Jess

[o_man_ra23]

jb_22, that link has errors, sorry mate. Do outsiders need to be logged into evocoupe.net to be able to view it??

[jb_22]

I got caught out with the forums' fancy link inserter thingy, it put two http://'s at the start of the link, should be good now!

[CheeseBiscuits]

Well had another shot at spray painting. everything went really well except for a minor detail of running out of paint even managed to start getting a really nice flat and in some areas even a fairly glossy coat.

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.

["Z" UTE]

Just a few thought that might make a difference on your next spray job.

One mistake a lot of "eager" amateur painters do make, is not mixing the paint thoroughly. I take about 10 minutes with a broad paddle mixing stick when mixing a 4 litre can. You must scrape the bottom of the can and lift the solids from the bottom to incorporate them in the mix.

I use 10 litre re sealable paint cans for mixing 4 litres or more of paint. These cans have a latch hoop that secures the lid.

Adding thinners must be done in small batches. Say you are adding 1 litre of thinners, you only add about 100mil first then 150ml, then 200ml. The thinner the mix becomes the more thinners you can add at one time. Dumping thinners in all at once will cause some funny reactions.

Store your old paint in an old non working fridge.

Something to keep handy at the paint mixing bench is an artists 1" bristle brush. Use the brush to remove the paint from the channel in the top of the can before you replace the lid. This makes sure you have a decent seal. The same brush can be used to clean the outside of your spray gun inside of the gun pot, and the inside of your mixing pot.

Use an old thinners can to put your cleanup thinners in. The solids will settle to the bottom of the can after a few days, and you can re use the thinners for your first flush of the gun when cleaning. I have a couple of these cans and alternate between them to allow settling time. I never throw thinners away!

If you mix too much 2 pac and you have use for it the next day, you can put the mix in a running fridge, the cold slows down the catalyctic reaction, and prevents the mix from going solid. Most 2 pac paints have a "mixed" pot life of at least 2 hours.

cheers Chuck.