Zinc Oxide primer for Steel

[Portable Welder]

I do alot of industrial railings and structural things of this nature.

I've been spraying rustoleum through a my quart cup gun for years and I have to thin it 65% paint and 35% laquer thinner.

I also use an oil base primer underneath.

I am not all that happy with the long term results.

I've had 2 different people tell me I need to use a Zinc oxide primer for better results.

I am thinking I need to move up to the airless commercial sprayer where I paint out of a 5 Gal. bucket and dont have to thin the paint.

Keep in mind we do our best to wipe our projects down with thinner to remove oil but have found in the past even after wiping & sanding there is still way to much oil left behind for automotive paints to stick to.

So Im still looking for an oilbase enamel that will hold up over time and need to find out more about this Zinc Oxide primer.

I do however use cold Galv for touching up repairs on Galvanized rails but its always a horrible color match and when trying to spray it through the cans the zinc particles have a habbit of clogging the tips.

[diamondback]

the benefit of the zinc is in the cathodic reaction. What you are adding is a sacrificial element to the paint that wont turn colors when it oxidizes.

Think of an outboard motor on a boat, they put those blocks out there that are made of zinc so the salt or just the unbalanced ph level in the water will attack it instead of the aluminum housing.

Pipe lines do this as well but on a much larger scale where they will bury large amounts of steel, often railroad rails due to chemistry. They will connect them electrically and add a small amount of current to the system. This makes the rails become sacrificial and protects the pipe. It is alot more complicated but you get the picture.

So if it is suitable maybe there is a place for zinc oxide primer.

[DDA52]

I used to use a zinc oxide primer all the time. It is very good stuff. No idea who made it because it was a rebranded house brand. I have since started using a plain old shop coat primer. It is fairly thick, but I do not have to thin it very much for some reason. I just buy it by the 5gal bucket and transfer a gal into another can...add 1/2 cup or so of thinner and mix...perfect every time. At 24 clams a bucket, it works out way cheaper than the zinc oxide and so far, has had good results.


For cold galv, try ZRC. They have a dark galv and a lite colored one. The lighter colored one matches most hot dip pretty well. The ZRC is very good stuff....and has a pretty good price tag, too....well compared to Rusto anyway.

[fabricator]

What exactly is the problem ? rustoleum primer and paint is all i mostly use.It does take many days if not weeks to set up hard other than that im happy with the results.Have you tried acid etch primer?costly but in some cases it is a better alternative.I also do not thin my paint that much I go about 10 to 1.

[bvweld]

ZRC is good and here is another http://www.briteproducts.com/shop/index.htm I hear you on the paint prep. Hard to get that oil film off especially on bigger jobs. I started using a diluted phosphoric acid solution in a garden sprayer to cut through it, followed by a rinse. As far as paint I have been using Rustoleum Industrial and I mix in some hardener to make the paint & primer a little harder.

[2tay530]

the other day at lows or home depot i found a new rustolium with zinc mixed in to it! It was also in a rattle can so for me(IDK about you) that adds to the convenience and ease of use. I've tried to thin down rustoleum but I've never got it to spray right.

[DDA52]

There is a foolproof way to see if a zinc paint is good or not. Weigh the can. The ZRC is over 95% zinc and the cans are flippin heavy, even the spray bombs. If the paint you choose weighs the same as or just slightly more than normal oil paint, like Rusto, it isn't as good. The ZRC cans weigh three or four times what a normal can would weigh.



http://www.zrcworldwide.com/p_zrc.asp

[Sberry]

There is no substitute for epoxies but they are hazardous to spray.

[blazehaze69]

We used epoxy paint on the aircraft when I was in the Navy. It was good stuff but you had to 'suit up' before painting. As the skin of the aircraft was aluminum, I think (it's been 40 plus years) we applied alodine and zinc chromate before shooting on the paint. BTW, the aircraft were Douglas A4 Skyhawks. They were cool little bombers!

[pthunberg]

I use the Pittsburg brand zinc oxide. Don’t have to thin it with regular spray rig but it does stink, a lot wear a respirator with charcoal filter. As for matching galvanized finishes I use rusto cold galv on old or dark galvanized and on new or bright galvanized I just over coat it with silver rusto. Usually it matches perfectly.