Best primer to paint steel

[mickylongtime]

10 hours ago, jadee said:

I like Rust-Oleum, you can get it from Home Pro. There's a spray version that combines primer and undercoat that's pretty good. Covers really well compared with others. 

Yes I've used Rust - Oleum it's very good, I gave it two coats very good body in the paint. 

[impulse]

6 hours ago, Yellowtail said:

Mill finish AL should cost about 4-5 times what steel costs 

  

That's on a per kg basis, I think.  But aluminum is 1/3 the weight of steel.  So the cost difference isn't as bad as many think.  But then, getting someone to weld on the aluminum will be a lot harder than fabricating steel.  Offset by the corrosion resistance of aluminum, which means less (or no) painting.  Lots of variables in that equation...

 

If the OP does go with steel, I'd suggest working out a way to prime the inside surfaces so it doesn't rot as fast from the inside out.  It's not so hard to do.  But it does require some thought.  It's still going to rot, but not as fast.

 

Edit:  I'd add that I had pretty good luck with the local Thai brands of red oxide primer.  Much less expensive than Rust-O-Leum.  But then, I only stayed in Thailand 7 years, so my longest lasting projects were 6 years old when I left.  They still looked good, though.  I did have to thin them to get a smooth coat without "gloppy" brush marks, but I have the same problem with Rust-O-Leum here in the States- especially in the hot sun when the paint dries real fast.

 

Edited September 13, 2020 by impulse

[transam]

14 hours ago, Yellowtail said:

 

Galvanized will generally not scratch through, and even if it does, and long as the scratch is less more that about 3mm wide it will not rust. The zinc corrodes galvanically protecting the steel until it is all corroded away.

 

Also, if you're using tubing the inside of the tube is coated as well.

 

Fabricated steel products welded together from hot-dipped galvanized sheet and tubing and welds coated with zinc-rich compound easily last 20 years in extreme summers and winters without significant corrosion. 

Tell that to my galvanized roof guttering, that has a few rust leaks.........????

[Yellowtail]

8 hours ago, impulse said:

  

That's on a per kg basis, I think.  But aluminum is 1/3 the weight of steel.  So the cost difference isn't as bad as many think.  But then, getting someone to weld on the aluminum will be a lot harder than fabricating steel.  Offset by the corrosion resistance of aluminum, which means less (or no) painting.  Lots of variables in that equation...

 

If the OP does go with steel, I'd suggest working out a way to prime the inside surfaces so it doesn't rot as fast from the inside out.  It's not so hard to do.  But it does require some thought.  It's still going to rot, but not as fast.

 

Edit:  I'd add that I had pretty good luck with the local Thai brands of red oxide primer.  Much less expensive than Rust-O-Leum.  But then, I only stayed in Thailand 7 years, so my longest lasting projects were 6 years old when I left.  They still looked good, though.  I did have to thin them to get a smooth coat without "gloppy" brush marks, but I have the same problem with Rust-O-Leum here in the States- especially in the hot sun when the paint dries real fast.

 

 

And AL is not as strong as steel so you typically have to use more, and steel lasts longer. After a few years, mill-finish AL starts to look pretty crappy, and paint options are pretty limited. Unless you plan to do the welding yourself, it will be very difficulty to find a shop to fab it for you, and extremely difficult to a welder to work on site that can provide decent results.

 

Stainless will generally be cheaper and easier to work with, and there are no shortage of shops around that can build and install it. 

 

Again, if one goes with channel and or angle rather than tubing there there is no "inside" that has to be painted. 

[Yellowtail]

1 minute ago, transam said:

Tell that to my galvanized roof guttering, that has a few rust leaks.........????

Operator error..... 

[transam]

13 hours ago, Lacessit said:

Has to be a scratch right through to the underlying steel, even then the sacrificial protection will keep it sound until someone decides to do a touchup with zinc-rich primer in the affected area.

IMO corrosion science is not your area of expertise.

Rust is............????

PS. My galvanized guttering has numerous rust leaks.....IMO, my eyesight is OK....????

[transam]

11 minutes ago, Yellowtail said:

Operator error..... 

It is still rust..

 

I tore apart and totally rebuilt my Honda lawnmower, of which the only part Honda is the engine, the rest had rusted away, painted with no primer.

Stripped all the paint, pop riveted patch panels (no welder), then painted it with TOA Rust-Tech 2 part paint, gave it a couple of days to harden then can sprayed red paint to look original. Whilst I was at it, I used the same paint on "her" rusted wheelbarrow, Rust-Tech did a good job, still no rust.

The downside of RT was, difficult to get a good finish, but it could have been my brush....

[Lacessit]

20 minutes ago, transam said:

Rust is............????

PS. My galvanized guttering has numerous rust leaks.....IMO, my eyesight is OK....????

Your galvanized guttering has numerous rust leaks because there's something accelerating the corrosion process. Galvanised guttering in a non-marine environment should last at least 50 years. I've seen rust-free galvanised at Orroroo, South Australia which is 150 years old.

Check out your roof, if there is any copper present it is curtains for anything galvanised downstream of it. Also Google the term " inert catchment corrosion"

[Susco]

3 minutes ago, Lacessit said:

Your galvanized guttering has numerous rust leaks because there's something accelerating the corrosion process. Galvanised guttering in a non-marine environment should last at least 50 years. I've seen rust-free galvanised at Orroroo, South Australia which is 150 years old.

Check out your roof, if there is any copper present it is curtains for anything galvanised downstream of it. Also Google the term " inert catchment corrosion"

Not sure where the sea is in Ubon

[transam]

2 minutes ago, Lacessit said:

Your galvanized guttering has numerous rust leaks because there's something accelerating the corrosion process. Galvanised guttering in a non-marine environment should last at least 50 years. I've seen rust-free galvanised at Orroroo, South Australia which is 150 years old.

Check out your roof, if there is any copper present it is curtains for anything galvanised downstream of it. Also Google the term " inert catchment corrosion"

Eeeer, no, we are talking paint, not my rusted out galvo guttering, or my 1964 MGB, or even my 1976 Pontiac.....????..............????

[Lacessit]

2 minutes ago, transam said:

Eeeer, no, we are talking paint, not my rusted out galvo guttering, or my 1964 MGB, or even my 1976 Pontiac.....????..............????

I get it, your excuse is I am off topic. As I recall, I was not the person who started talking about their rusted out gutters, and i was trying to help.

Want to be on my ignore list? I have plenty of room.

[giddyup]

The contractor who is going to build my pergola in steel says he is going to use galvanised. I believe that galvanised needs a special preparation before painting, I read washing with white vinegar first will do the job.

[Lacessit]

Just now, giddyup said:

The contractor who is going to build my pergola in steel says he is going to use galvanised. I believe that galvanised needs a special preparation before painting, I read washing with white vinegar first will do the job.

Vinegar is acetic acid, it will give the zinc a mild etch which helps paint adhesion.

[transam]

1 minute ago, giddyup said:

The contractor who is going to build my pergola in steel says he is going to use galvanised. I believe that galvanised needs a special preparation before painting, I read washing with white vinegar first will do the job.

Correct, and a paint that is advertised as can be used on galvo, otherwise it will peel in no time, I have the T-shirt....Dohome has such a paint, 500bht a gallon in a few colours....

[transam]

5 minutes ago, Lacessit said:

I get it, your excuse is I am off topic. As I recall, I was not the person who started talking about their rusted out gutters, and i was trying to help.

Want to be on my ignore list? I have plenty of room.

Touchy........... Ignore list, do what you like chap......????

[Lacessit]

2 hours ago, transam said:

Touchy........... Ignore list, do what you like chap......????

Let's just say i have a low tolerance level for certain types of people. On ignore now.

[Yellowtail]

4 hours ago, giddyup said:

The contractor who is going to build my pergola in steel says he is going to use galvanised. I believe that galvanised needs a special preparation before painting, I read washing with white vinegar first will do the job.

Using vinegar will help, but unless you use the right primer it it is not likely to to stick. RusTech will absolutely stick, as will zinc-chromate, and some of the zinc-rich primers. ZRC is great for treating welds. 

 

I would go with RusTech, but again be advised it has a short pot-life so you have to work quickly.  

 

[impulse]

18 hours ago, Yellowtail said:

 

And AL is not as strong as steel so you typically have to use more, and steel lasts longer. After a few years, mill-finish AL starts to look pretty crappy, and paint options are pretty limited. Unless you plan to do the welding yourself, it will be very difficulty to find a shop to fab it for you, and extremely difficult to a welder to work on site that can provide decent results.

 

Stainless will generally be cheaper and easier to work with, and there are no shortage of shops around that can build and install it.   

 

Again, if one goes with channel and or angle rather than tubing there there is no "inside" that has to be painted. 

 

All true, but when someone wants to build a strong, durable, rust free structure on their boat, aluminum is the go-to.  It's not as strong as steel, but at 1/3 the weight, it doesn't have to be to support itself.  That said, anodized is the starting point- not mill finished.

 

The problem with stainless is they skimp on the wall thickness for most consumer profiles like square tube.  Great for decorative.  Not so much for load bearing structural projects.  You can get a thicker wall, but bring money.  Lots of it.

 

And for decorative structures, rectangular or square tubing presents much nicer finish than angle or channel.

 

Edited September 14, 2020 by impulse

[Yellowtail]

7 hours ago, impulse said:

 

All true, but when someone wants to build a strong, durable, rust free structure on their boat, aluminum is the go-to.  It's not as strong as steel, but at 1/3 the weight, it doesn't have to be to support itself.  That said, anodized is the starting point- not mill finished.

 

The problem with stainless is they skimp on the wall thickness for most consumer profiles like square tube.  Great for decorative.  Not so much for load bearing structural projects.  You can get a thicker wall, but bring money.  Lots of it.

 

And for decorative structures, rectangular or square tubing presents much nicer finish than angle or channel.

 

 

Actually for boats I think it's mostly 316L for towers, rocket-launchers, outriggers, hardware and whatnot. Seeing more powder-coated Al for lower end marine applications. In any event, weight isn't much of a concern when building a permanent structure outdoors. Also, Al is much more subject to fatigue and cracks than is steel, which is a concern for permanent structures.  

 

Stainless is much stronger than mild steel so it can run a bit thinner than mild, and much thinner than Al. Heavy-wall is the same cost per-unit weight as thin tubing so 

 

Anodized is great, touching up the welds can be a hassle unless  you're going bolt-together.

 

Yeah, tubing looks better, but unless your structure is designed to drain, corrosion can be a big problem. 

 

The biggest issue is the number of guys doing custom stainless compared to the number of guys doing custom aluminum. Personally, I would go with hot-roll steel and paint it. 

 

 

[giddyup]

The "contractor" just quoted me 23,000 baht to make this 6m x 3m pergola. This includes all the materials and the painting of the finished product with 3 coats of paint, including a galvanised steel primer. Does this seem fair? Pretty hard to know exactly, it's like how long is a piece of string. He's done a few jobs for me previously and his work is generally pretty good, but he does seem a tad on the expensive side.

[Yellowtail]

1 hour ago, giddyup said:

The "contractor" just quoted me 23,000 baht to make this 6m x 3m pergola. This includes all the materials and the painting of the finished product with 3 coats of paint, including a galvanised steel primer. Does this seem fair? Pretty hard to know exactly, it's like how long is a piece of string. He's done a few jobs for me previously and his work is generally pretty good, but he does seem a tad on the expensive side.

Does that include concrete?

 

Sounds okay to me, but If he's providing the material, you should get a bill of material the includes the thickness of the material as well as the brand and type of paint. 

 

I generally agree to the price, subject to approval of drawings and material.

[giddyup]

17 minutes ago, Yellowtail said:

Does that include concrete?

 

Sounds okay to me, but If he's providing the material, you should get a bill of material the includes the thickness of the material as well as the brand and type of paint. 

 

I generally agree to the price, subject to approval of drawings and material.

No concrete needed. The front posts will fasten to the existing cement at the front fence, and the rear is attached to the steel rafters of the house. The pics give some idea.

Edited September 15, 2020 by giddyup

[impulse]

9 hours ago, Yellowtail said:

 

Actually for boats I think it's mostly 316L for towers, rocket-launchers, outriggers, hardware and whatnot. Seeing more powder-coated Al for lower end marine applications. In any event, weight isn't much of a concern when building a permanent structure outdoors. Also, Al is much more subject to fatigue and cracks than is steel, which is a concern for permanent structures.  

 

Stainless is much stronger than mild steel so it can run a bit thinner than mild, and much thinner than Al. Heavy-wall is the same cost per-unit weight as thin tubing so 

 

I'm not disagreeing with any of your points.  But just a little info from bopping around China for 10+ years and buying/ exporting a lot of stainless to customers in the USA. 

 

For the most part, that pretty, polished decorative stainless you see in the builders' markets is made of 201 stainless.  That's the stuff that's affordable for "around the home".  Sometimes, it's 304 SST (or more likely the Chinese alternative to 304, which is 302- 1Cr18Ni9)  They're all great for indoor projects, but they do rust and they do stain over time.  They don't disintegrate like carbon steel, but you'll be polishing the rust stains off of them every year or so in humid outdoor projects.  And generally speaking, the wall thickness is adequate for decorative fluff, but not for structural beef.

 

If you want 316 or 316L, you're looking in very different material markets, generally those that cater to marine uses and refineries.  Not the markets catering to folks that are adding on to their home.  And when you go to those industrial markets to buy 316L and/or thicker structural stainless, bring money.  Wheelbarrows full.

 

Edited September 15, 2020 by impulse

[sometimewoodworker]

1 hour ago, impulse said:

For the most part, that pretty, polished decorative stainless you see in the builders' markets is made of 201 stainless.  That's the stuff that's affordable for "around the home".  Sometimes, it's 304 SST (or more likely the Chinese alternative to 304, which is 302- 1Cr18Ni9)  They're all great for indoor projects, but they do rust and they do stain over time.  They don't disintegrate like carbon steel, but you'll be polishing the rust stains off of them every year or so in humid outdoor projects.  And generally speaking, the wall thickness is adequate for decorative fluff, but not for structural beef.

I’m sure you know more than I on the subject. Our gate is now 4 years old no rust at all the only problem has been an investigative  snake 

[Yellowtail]

11 hours ago, impulse said:

 

I'm not disagreeing with any of your points.  But just a little info from bopping around China for 10+ years and buying/ exporting a lot of stainless to customers in the USA. 

 

For the most part, that pretty, polished decorative stainless you see in the builders' markets is made of 201 stainless.  That's the stuff that's affordable for "around the home".  Sometimes, it's 304 SST (or more likely the Chinese alternative to 304, which is 302- 1Cr18Ni9)  They're all great for indoor projects, but they do rust and they do stain over time.  They don't disintegrate like carbon steel, but you'll be polishing the rust stains off of them every year or so in humid outdoor projects.  And generally speaking, the wall thickness is adequate for decorative fluff, but not for structural beef.

 

If you want 316 or 316L, you're looking in very different material markets, generally those that cater to marine uses and refineries.  Not the markets catering to folks that are adding on to their home.  And when you go to those industrial markets to buy 316L and/or thicker structural stainless, bring money.  Wheelbarrows full.

 

 

I thought we were talking about custom fabricated products for permanent outdoor installations, not cheap, SG Chinese consumer goods.

 

While I can't speak to China, I did spend over thirty years building made-to-order fabricated steel products, the last twenty of which were in Thailand. I can assure you that 304 is readily available in Thailand, and while 316L is not as common, it it is also available and generally does not cost significantly more than does 304. There are a lot of traders in Thailand which makes stainless prices competitive.

 

The "corrosion" you see on stainless is often not corrosion but rather staining from carbon contamination, or from SG fasteners. Any time you drill, punch, roll, draw break or perform any other process on stainless using carbon steel tooling, the carbon residue can oxidize and stain the stainless. This is why you often see "rust" around stainless fasteners, fittings or welds.