The Spray Painting Thread

[RPM016T]

Deoxidine 624 made by PPG, or De-ox-it. Will provide temporary protection from rust and leave a zinc phosphate coating. It is also primer friendly, although once left for a while i would advice of another coating of it. Depending on strength required, simply dilute with water, scrub rusty area's and other area's you wish to protect with scotch bright then thoroughly wipe of with damp rag.....

Just on that - surely its bad to wipe off using a damp rag? water? I had just been using a heap of towels as I thought water would be a big no no?

[jeffro ra28]

I thought so to mate. But PPG are big players in the game id believe pretty much any of their instructions.

I suppose it goes to show once the dexodine is applied it conditions and coats the metal immediately and water cannot affect it as easily. You do however need to dry the metal after wiping with damp rag.

Just follow the instructions mate it works.

["Z" UTE]

RPMO16T, use your phospheric acid to de rust the surface, then immediately coat the panel with an epoxy primer. The epoxy primer will adhere perfectly to the treated surface. The paint shop you are going to use should be consulted as to what brand they use.

The first thing a panel shop will do, is shoot a coat of epoxy anyway, so you may as well do it. The panel shop uses this epoxy coat to assess where any further body repairs are needed, then they patch, file, bog, hifill and prime them colour coat.

By trying to leave the car as bare metal, you are only creating work for yourself and the guys at the panel shop.

When cars are blasted with Wallnut shell, the shell leaves behind a Wallnut oil, this is easily removed with prepwash/Prepsol, and this is the norm in a full bare metal hot rod build. As soon as they work the area, it is treated with the phospheric acid, and epoxy primed. The mere act of laying a bare hand on an untreated panel will result in rust, simple as that.


Edit: Jeffro is 100% correct, follow the instructions to the letter.


cheers Chuck.

[RPM016T]

RPMO16T, use your phospheric acid to de rust the surface, then immediately coat the panel with an epoxy primer. The epoxy primer will adhere perfectly to the treated surface. The paint shop you are going to use should be consulted as to what brand they use.

Cheers for the advice guys. Z, Only reason I'm not doing this is because I'm still yet to decide on a painter, brand of paint etc.. Defintely seems like the logical thing to do though. I'll go to crash supplies and suss out this PPG stuff. cheers!

[Jeri]

[QUOTE="Z" UTE;1070182]
The most cost effective spray gun I ever bought was a Bluepoint gun, from Snap On Tools, just over a hundred bucks. I still use this gun to this day for topcoat and clearcoat, and it is over 6 years old, probably sprayed a dozen cars with it. So next time you see a Snappy truck outside a workshop, jump in and buy one.

cheers Chuck.[/QUOTE]

Hi Chuck would this be the gun that you bought?



[URL="http://buy1.snapon.com/catalog/tools.asp?tool=all&Group_ID=22684&store=snapon-store"][/URL]

[twentyEight]

Jeri, the gravity feed guns as you have pictured are high volume(paint) low pressure (air),ie. less airflow required to get a given amount of paint onto the job, as gravity delivers the fluid to the tip.

Note: Not all gravity feed guns are classed as HVLP.

Snap-on also have this situation.

There is a Blue Point Non-HVLP Gravity Feed Gun, and a Blue Point HVLP Gravity Feed Gun.



http://buy1.snapon.com/catalog/tools...tore=australia

["Z" UTE]

Jeri, I have just checked the online catalogue, the gun I have is no longer listed! Gravity feed 1.4mm tip with a full alloy pot. Sorry but that is all the details I have.

cheers Chuck.

[DrNick]

1.4mm is fine for acrylic right?

I just switched to a DeVilBiss 1.4mm HVLP gravity feed but plagued by orange peel in the finish. I get really even coverage and excellent gloss but orange peel. I have never had this issue before with any of my other cheaper guns (Star suction feed 2.0mm, unknown brand gravity feed touchup 0.8mm).

I did have to increase the line pressure above what the box said because it just wasnt atomizing at the lower pressure they stated. But I dont see how this could affect it.

Suggestions welcome

["Z" UTE]

DrNick, as the weather warms up, you will need to add more thinners to the mix. Put simply the thinners are evaporating very quickly, and without the thinners the paint will not flow out thus leaving you with orange peel. The need to raise the air pressure also points to a paint mix that is a liitle to thick.

cheers Chuck.

[ian]

as chuck said
thinner paint , lower air pressure reduces orange peel

[DrNick]

Thanks guys, I will definitely make this adjustment when I continue work on the car. Theres plenty of panels to do so I've got time to work it out.

Out of curiosity, is there any reason why the thinning ratio I was using in the past worked fine on my old guns but not on my new HVLP. Is it common that HVLP requires thinner mixtures? (I've been using 1 part paint 1.5 parts thinner for everything til now).

[viccelicara23]

I am now putting the clear coat on my car and i found that i was getting a white dust below and above where im spraying. It is nearly like the paint is drying before it hits the panel. the temperature was around 27 degrees. the thinning raatio was 1 part clear to 1.5 thinners as per the paint instructions. What am i doing wrong?

["Z" UTE]

I am now putting the clear coat on my car and i found that i was getting a white dust below and above where im spraying. It is nearly like the paint is drying before it hits the panel. the temperature was around 27 degrees. the thinning raatio was 1 part clear to 1.5 thinners as per the paint instructions. What am i doing wrong?

This is called dry spray, and is a result your air pressure being too high, and quite possibly your paint being too thick.

Manufacturers thinning ratio is only a guide, and the amount of thinners will depend on the temperature of the day. Hotter days and the thinners evaporate before the paint hits the panel, leaving dry sprayed areas at worst case, and in a not so bad case orange peel.

Thinners, also called reducers perform a couple of functions, thin down the mix to make it spray more evenly (ie. better atomistaion), and secondly thinners are a levelling agent, which helps the paint flow out and sit flat on the surface of the job. Do not be afraid to use 10-20% more thinners than what the manufacturer has indicated on the can.


For clearcoat, my final mix is 20% paint 80% thinners, otherwise that stuff will not flow out and it will be orange peel city. This mix goes on on top of the first 2-3 coats of clear, it tends to meld all the paint together, and level it giving a nicer gloss level that is really easy to buff.

cheers Chuck.

[DrNick]

For clearcoat, my final mix is 20% paint 80% thinners, otherwise that stuff will not flow out and it will be orange peel city. This mix goes on on top of the first 2-3 coats of clear, it tends to meld all the paint together, and level it giving a nicer gloss level that is really easy to buff.

cheers Chuck.

im going to start doing this. i remember seeing the teacher at tafe do this years ago as well for the last couple of coats (he would just look at whatever amount is in the cup at the end and add some thinners to it, spray a coat, thin some more etc).. the finish was nice and i remember making a note to do that,but i guess i got lazy as time went on hehe

[o_man_ra23]

Up here when it isn't pissing rain, I usually ran about a 1 to 2 mix of acrylic paint to thinner due to the heat. Even then it dry sprayed often, and I had to increase the mix. DrNick, being in WA, you will probably be suffering the same.