Primer ?? use it or not ??

This for a shed I want to paint... I have been told save the $$$ on primer and put an extra coat of paint on ... Has anyone ever done this or is some one pulling my leg ??

I have heard that primer on a tractor isn't nessary either .. the man show me his tractor and told me he never use's a primer ... he use's paint , that way if he miss'es a spot it doesn't show as soon ...

Any thoughts on that ??

THANKS .. Mark

Im not a painter but I know if you want to paint bare metal you should use primer.If the old paint is good and not cracked and peeling you could clean and sand and paint if you use enamel on enamel or as long as the new paint/thinner is compatible with the old and you dont have a chemical reaction,you can maybe paint over the old paint.I always used enamel so thats all I know about.Lacquer thinner will remove enamel even after it dries so you cannot paint lacquer over enamel or enamel over lacquer I dont think.You might put some kind of primer over lacquer and paint it then,not sure.The best thing to do is take the old paint off,primer,sand,put new paint on.I dont have any idea if you are painting wood.Oil base is different than the other stuff is about all I know however if you are having a problem with rust or some kind of stain coming through your painted walls you can put primer on that will stop that.Kilz is one I used and it works.Outside on a house it might last longer with the right primer under it.If you use oil base you might put another coat on and skip the primer but the wood drinks that paint and if primer was cheaper I would use that first to cut the cost down.At the places I worked at whenever they painted metal it had primer under it.Painting 15 or 20 gallons of paint a day or more,they would have skipped it if they could get away with it to save money,and sometimes they did.I dont know what the reason was,but I know they primered most everything.Maybe on bridge beams underneath a bridge they didnt figure they needed primer or something,I dont know,I wasnt a painter.Maybe a real painter will tell you better.

Since I had a peeling problem on my farm buildings, I use only a premium quality latex primer on them. My barn got two coats of the primer in '96 and from a 'ways off, still looks good. I'm going to "go" another year at least. Primer is made to stick and the finish coat is made to wear. Primer is relatively soft and can flex with temperature changes whereas finish coat is hard and doesn't flex as much. That is why I put on a double coat of primer. The finish coat really does need that primer coat to hang on to - on buildings anyway! Of course, proper and adequate preparation is the key to success.

By all the accounts from people who should know, International Harvestor never used primer. They painted right over bare metal.

If you use Primer, it should last longer. At least that has been my experience.

I painted over a barn that had multicolored steel tin. Blue red white ugly. I painted it barn red with paint from Fleet Farm. 5 gallon buckets about 70 bucks for a bucket. It is an OIL BASE paint.
We powerwashed the tin and let it dry. Then painted. It has been 6 years now. It's the way to go in my book.
I also painted a tin roof from green to white to shed the heat and sun.
It is working great.
I'm not to hot on a latex paint for outside
MY 2 cents of experience.

Farmer

Without a good primer you can watch the paint flake off the new lumber is about a year. Double cloth without primer you have the same result crap. Learned from an old school carpenter 40 years ago.