General Galvanneal Questions

[Anon Ent Titty]

Total metalworking newby here. I'm part way through skinning my shorty after my 14.5" raise. My research told me I wanted 16 guage galvanneal, which I had a **** of a time sourcing here in SoCal.

I've searched the web for answers about galvanneal with little results, and I have some lingering questions that's gonna be basic common knowledge for most of you old heads.

• Process
  
  Does the annealing process on the galvanneal cause the zinc layer to fuze simply to the surface, or does it permeate the whole sheet? If my sheet gets a surface scratch, do I need to worry about that spot no longer having galvanized protection? If I make a cut, do I need to prime the non-factory edge? Do you need to prime then paint? Do you want to scuff up the primer to give it "teeth" before your finish paint?
  
  
• Paint prep
  
  I found a memorandum by a company called De La Fontaine about painting galvanneal. They say to prep with a rag & turpentine or other mineral spirits. I'm in California, so that's a no-go. (For those of you who don't know, Cali won't let you buy mineral spirits.) It says NOT to use vinegar, muriatic acids, or other acids as "these products do nothing to improve paint adhesion in any consistent manner."
  
  
• Prime / Paint?
  
  My understanding was that part of the corrosion resistance of galvanneal assumed a good coat of paint. None of the re-skinning tutorials I see prime/paint the sheets before riveting them in, but some prime them after riveting. This means there will be parts that are now hidden that will not get primed. Do we just assume these overlapped parts are... gonna be fine? None of Bluebird's original sheet metal comes unprimed/unpainted. What's the prevailing philosophy on this? Does galvanneal NOT need a coat of paint for basic protection? When it says it's made to be "paint ready" does that mean no primer?
  
  
• Rust
  
  As a newby, I feel OCD about trying to remove every spot of rust. I'm using regular 12 guage carbon steel angle iron for my newly fabricated "hat channels" and I painted them all with Rustoleum rusty metal primer: another step I never really see in tutorials. Am I just being paranoid? Isn't there a concern of the interaction between the carbon steel hat channels and the galvanneal?
  
  
• Guage selection
  
  I admit that the 16 guage is a pretty thick. I like that it's super sturdy, but definitely gonna add some weight to the bus. Probably could have gotten away with 18, and saved some money & finished weight. (Original skins were about 18 guage) At least I'm good and bullet-proof for the coming post-Covid apocalypse. :biggrin: I started with skinning the back first, and bending that 16 guage single handedly with ratchet straps is no joke.
  
  
• Sourcing
  
  I just thought I'd share some prices and sources I found in SoCal when shopping for my galvanneal. I wish we had a sourcing directory sticky, but a few days on the telephone with every metal supplier in a 3 hour radius and this is what I've got:
  
  Places who carry galvanneal: ​
  Ryerson.com carries it, but wasn't able to get a quote back
  competitivemetals.com
  rolledsteel.com
  maashansen.com
  onlinemetals.com (I ordered, paid, and waited for my order. They sent it to some company in Connecticut by accident and couldn't recover it for me. They had to re-order and reship, but I cancelled due to the long delay and customer service issues.) About $123 per sheet, + $250 shipping
  tuskermetals.com is who I eventually drove 2.5 hours (one way) to pick it up from this week. About $180/sheet, great service, good small/medium sized shop in Temecula, CA.
  
  It's worth noting, my sheets were 28" x 120". When you're pricing out your sheets, ask them if they give you the remnants of the sheet they cut for you. Some companies automatically charge you for the whole 48 x 120 sheet. Some let you keep the remnants, some don't. The cheapest options are those that charge you for exactly the metal you want. I could have used the other pieces for under-bus storage bins, but I'll bite that bullet when the time comes.
  

:Thanx:

 

[magnakansas]

try to answer your questions

https://www.metalsupermarkets.com/what-is-galvanneal/ GO HERE FIRST.

it is just a zinc coating process that uses less zinc thickness than hot dipped zinc.

I would imagine painting is a little easier than hot dipped zinc products.

yes if you scratch it very deep at all there is exposed steel. The whole idea of the galvanneal process is to use less zinc. and faster to process.

even with a scratch the idea behind coating steel with zinc is that the zinc is still more of the sacrificial anode than the steel.

I like acetone as a degreaser. nasty stuff. If I lived in Ca. I suppose I would make a trip across the boarder and buy a few gallons of product that is intended to be a paint prep or acetone... what ever is cheaper.... I used to live in the los angeles area in the early 70's the sky was brown..... I think the clean air stuff is a good thing, but sometimes makes doing stuff incredibly difficult.

there are some "weld through" zinc rattle can products... you can spray those angle iron parts and weld then spray the welds with a zinc spray afterwards and then paint on top of that... maybe when the paint gets nicked you still have some corrosion protection.... I think the old superior brand of buses used more hot dipped type of steel sheet and seem to be very rust resistant. S ame for some early to mid sixties ford vans.... but it was a bitch to get paint to stick. specific primers for best performance..

ppg and other paint companies call it a "paint system" for a reason. gets pricey but when done by the book, comes out all shiny, flat and long lasting.

I think people that sell paint for ships and boats probably have the best experience for painting stuff like our steel school buses.

if the rest of the bus is 16 gauge, then I would stick with 16 gauge. gonna fall under the rule of the weakest link.

william

 

[Anon Ent Titty]

I used to live in the los angeles area in the early 70's the sky was brown..... I think the clean air stuff is a good thing, but sometimes makes doing stuff incredibly difficult.

I've heard that jogging in L.A. is the health equivalent of smoking a pack of cigarettes per day. When I first moved there, I was at a friends house and drank some of his tap water. 3 people just stared at me like I had just licked someone's ass. He says "Bro, I don't even give my DOG that water, DON'T DRINK THAT!"

I think people that sell paint for ships and boats probably have the best experience for painting stuff like our steel school buses.

So maybe a specialized paint store would be the place to ask? I know a lot of us bus builders use galvanneal, but I can't find anyone talking about which primers, and proper paint prep.

if the rest of the bus is 16 gauge, then I would stick with 16 gauge. gonna fall under the rule of the weakest link.

The old existing bus skin was 18, I'm putting up 16.

 

[ChurchBuz]

The old existing bus skin was 18, I'm putting up 16.

Are you just adding material to fill the holes from the raise?

The jump from 18 to 16 shouldn’t add too much weight. But remember that the higher up the weight, it raises your center of gravity.

If reskinning the roof, I would not increase the thickness.

I would be more inclined to go down to 20ga and spray it with foam underneath, and only walk on the ribs.

 

[Albatross]

Guage (sic)selection
I admit that the 16 guage is a pretty thick. I like that it's super sturdy, but definitely gonna add some weight to the bus. Probably could have gotten away with 18, and saved some money & finished weight. (Original skins were about 18 guage) At least I'm good and bullet-proof for the coming post-Covid apocalypse. :biggrin: I started with skinning the back first, and bending that 16 guage single handedly with ratchet straps is no joke.

This should be your first decision, and you should match the original gauge of the original skin, for a number of reasons. Firstly, it is easier to match to the level of the original skin that you should be mating it with. Doing a roof raise will raise your center of gravity, increasing thickness on the outer skin will exacerbate this; granted, it's largely going to be more hollow/less dense than the lower portion of the bus, so this may be moot, but it is also likely to make your bus less steady when you're turning or hit a bump/pothole. And 18 gauge is fine, 16 isn't going to be more 'bulletproof' because I can still dent it with a fist; a rock or something falling on it will still cause damage.

Does the annealing process on the galvanneal cause the zinc layer to fuze simply to the surface, or does it permeate the whole sheet? If my sheet gets a surface scratch, do I need to worry about that spot no longer having galvanized protection? If I make a cut, do I need to prime the non-factory edge? Do you need to prime then paint? Do you want to scuff up the primer to give it "teeth" before your finish paint?

Both, and neither; https://en.wikipedia.org/wiki/Galvannealed.

Worrying about a surface scratch depends on the depth of the scratch. It's basically like everything else, if it's shallow/surface, then it's largely up to your comfort level or how anxious or how much of a worry-wort you are.

Priming a cut is the the kind of commiefornia obsession over the most minor of details that makes the rest of the real world hate you people. If you're not sending it to outer space or the bottom of the ocean, details like that are entirely irrelevant in 98% of real-world situations. Especially if you give it a proper coating once assembled.

If you want a properly-finished final coat, then you should follow the directions of your coating system; if it says to prime (which almost all of them do), then you should prime. If it recommends sanding, or gives instructions for 'proper' sanding, then you should sand. This isn't one of those situations where you're going to get a 'right' answer from randos on the internet, especially if they don't even know what you're going to be using, because you don't even seem to know what you're going to be using.

Better yet, use something like Rhino-liner to coat your bus, and you'll likely be more 'bulletproof' as far as keeping your exterior coating intact and in one piece.

Paint prep
I found a memorandum by a company called De La Fontaine about painting galvanneal. They say to prep with a rag & turpentine or other mineral spirits. I'm in California, so that's a no-go. (For those of you who don't know, Cali won't let you buy mineral spirits.) It says NOT to use vinegar, muriatic acids, or other acids as "these products do nothing to improve paint adhesion in any consistent manner."

Acids eat metals and metal oxides, mineral spirits and other solvents remove oils and other things that prevent the chemical process of 'painting' and 'coatings' from working and properly adhering to the surface(s). You're not going to do yourself any favors using something like vinegar for paint prep, unless you're using it to scrub rust off, and going to follow it up with a water rinse and then some kind of a solvent wash to get it nice and clean.

Prime / Paint?
My understanding was that part of the corrosion resistance of galvanneal assumed a good coat of paint. None of the re-skinning tutorials I see prime/paint the sheets before riveting them in, but some prime them after riveting. This means there will be parts that are now hidden that will not get primed. Do we just assume these overlapped parts are... gonna be fine? None of Bluebird's original sheet metal comes unprimed/unpainted. What's the prevailing philosophy on this? Does galvanneal NOT need a coat of paint for basic protection? When it says it's made to be "paint ready" does that mean no primer?

This is because you don't seem to understand how the process works. Riveting is a mechanical process that uses pressure to squeeze a fastener into place, ideally tight enough to barely compress the metal sheets together and/or to a structural support. This inherently causes enough stress and strain to rip and tear pretty much any coating you're going to use. If you try to prime (or paint) beforehand, the coating would become dislodged/ripped/torn/damaged and would no longer function, since it would expose bare metal.

Galvanneal is a portmanteu of galvanize and anneal. It utilizes zinc as a coating layer, from galvanizing, and annealing, which is a heat-treating process to relax the interior stresses in the crystalline matrix of ferrous metals so that they conform to a new shape better and to give it better ductility. The process actually allows for some of the zinc to permeate a bit deeper into the steel than normal galvanization. Zinc is used because, like aluminum and magnesium, it doesn't rust/oxidize in air--or more appropriately, it always has a thin layer of oxide on it preventing further oxidation from occurring. This is suitable for preventing rust on ferrous metals, at least until the more brittle Zinc falls/flakes off.

You should coat metal after you've built something out of it if you want it to last in normal conditions. Coming 'paint-ready' just means that the manufacturer claims sufficient adhesion to most basic paint coating types that priming is not absolutely necessary, for the kind of guys that wind up painting stuff (like buses) outdoors where a 'clean environment' is more difficult to accomplish, which prevents dirt/dust/insects from being stuck in the paint as the chemical carrier (mineral spirits) evaporates.

Rust
As a newby, I feel OCD about trying to remove every spot of rust. I'm using regular 12 guage carbon steel angle iron for my newly fabricated "hat channels" and I painted them all with Rustoleum rusty metal primer: another step I never really see in tutorials. Am I just being paranoid? Isn't there a concern of the interaction between the carbon steel hat channels and the galvanneal?

This is a long debated topic, probably going on centuries, now, honestly. I, personally, am in the camp where it's always best to remove all oxidation prior to priming, so as to prevent cancer from forming sooner.

There is always some realistic concern over galvanic corrosion--what it's actually called when you have two dissimilar metals in direct contact with each other that cause corrosion when an electrolyte (such as the contaminants in rain water) come into contact. However, zinc being 'less noble' than the steel, will corrode/come off first. If you really want to min/max, though, put a primer coating in between, and instead of taking 10-20 years (depending on environment) you'll get something more like 20-40, possibly longer.

SPECIAL NOTE:
I would like to thank you for demonstrating a perfect example of why everyone makes fun of, and doesn't particularly like commiefornians--especially when they move into town.

You're never going to be able to comply your way out of that kind of tyranny.

If you want to do things "right", you should break the "law" (it really isn't, more like a 'municipal code') by crossing a state line and import your own mineral spirits for personal use.

 

[Anon Ent Titty]

Are you just adding material to fill the holes from the raise?

Yes. My roof is not being altered. Good note on the center of gravity. I plan on spray foaming and adding solar, so there will be a lot more weight up there before I'm done.

16 isn't going to be more 'bulletproof' because I can still dent it with a fist; a rock or something falling on it will still cause damage.

Of course I didn't think that 16 guage steel is actually bulletproof. I even put a smiley face afterwards, that's how you know it's a joke. :wink1:

Priming a cut is the the kind of commiefornia obsession over the most minor of details that makes the rest of the real world hate you people. If you're not sending it to outer space or the bottom of the ocean, details like that are entirely irrelevant in 98% of real-world situations.

You should coat metal after you've built something out of it if you want it to last in normal conditions.

Don't these statements contradict each other? Don't worry about coating every thing, but also you should coat everything if you want it to last?

I admitted to being a metal-working newby. Forums like these are where people come to learn and ask "dumb questions." These are the details that I'm trying to figure out. I might be an overthinker, but that comes from a place of recognizing my own ignorance. I have no mentor in this project, and I don't know what I don't know.
I'm pretty sure me living in California has nothing to do with anything mentioned here. Did someone from Cali touch you in the naughty place? IT WASN'T YOUR FAULT! You've got to let it go.

If you want a properly-finished final coat, then you should follow the directions of your coating system; if it says to prime (which almost all of them do), then you should prime. If it recommends sanding, or gives instructions for 'proper' sanding, then you should sand.

I do not yet have a coating system. I have a can of Rustoleum-equivalent metal primer that I bought from a hardware store. I'm here looking for recommendations on what system & method to use. I was asking about sanding because I was assuming that the instructions on a paint system might not be specific for galvanized or galvanneal. I would think that sanding on top of galvanized might flake off the zinc layer, no? Hence my question about if galvanneal only has a surface layer of zinc. I don't want to sand off the corrosion protection that I paid for.

This is because you don't seem to understand how the process works. This inherently causes enough stress and strain to rip and tear pretty much any coating you're going to use. If you try to prime (or paint) beforehand, the coating would become dislodged/ripped/torn/damaged and would no longer function, since it would expose bare metal.

I'm not referring to the point of entry by the rivet. (I am using Musegenis' & Demac's style of "wet riveting" with seam sealer.) I was referring to the section of new skin that will be outward facing, that will be overlapped by the existing skin. Once the sheet is riveted, this section will be hidden, and no longer be accessible to prime or paint.

SPECIAL NOTE:
I would like to thank you for demonstrating a perfect example of why everyone makes fun of, and doesn't particularly like commiefornians--especially when they move into town.

I'm sorry for whatever happened to you in California that made you feel so booty tickled. I wasn't defending their policies, and I've only lived here a couple years. I was just adding that as a disclaimer to clarify what was/wasn't available to me. It's a 7 hour drive to get out of state for me, so I have to work with what I can get locally.

 

[magnakansas]

Zinc coating

At the most a worn scotch brite pad. Otherwise you’ll sand right through the zinc.

Yea rusty o lee um on the edges where you cut. I really like the seam sealer and riveted seams. I would definitely do that. Paint over it.

Many primers should be painted over as soon as you can.

William

 

[DeMac]

Skoolie.Net Shared KnowledgeBase

Yes. My roof is not being altered. Good note on the center of gravity. I plan on spray foaming and adding solar, so there will be a lot more weight up there before I'm done.

Of course I didn't think that 16 guage steel is actually bulletproof. I even put a smiley face afterwards, that's how you know it's a joke. :wink1:

Don't these statements contradict each other? Don't worry about coating every thing, but also you should coat everything if you want it to last?

I admitted to being a metal-working newby. Forums like these are where people come to learn and ask "dumb questions." These are the details that I'm trying to figure out. I might be an overthinker, but that comes from a place of recognizing my own ignorance. I have no mentor in this project, and I don't know what I don't know.
I'm pretty sure me living in California has nothing to do with anything mentioned here. Did someone from Cali touch you in the naughty place? IT WASN'T YOUR FAULT! You've got to let it go.

I do not yet have a coating system. I have a can of Rustoleum-equivalent metal primer that I bought from a hardware store. I'm here looking for recommendations on what system & method to use. I was asking about sanding because I was assuming that the instructions on a paint system might not be specific for galvanized or galvanneal. I would think that sanding on top of galvanized might flake off the zinc layer, no? Hence my question about if galvanneal only has a surface layer of zinc. I don't want to sand off the corrosion protection that I paid for.

I'm not referring to the point of entry by the rivet. (I am using Musegenis' & Demac's style of "wet riveting" with seam sealer.) I was referring to the section of new skin that will be outward facing, that will be overlapped by the existing skin. Once the sheet is riveted, this section will be hidden, and no longer be accessible to prime or paint.

I'm sorry for whatever happened to you in California that made you feel so booty tickled. I wasn't defending their policies, and I've only lived here a couple years. I was just adding that as a disclaimer to clarify what was/wasn't available to me. It's a 7 hour drive to get out of state for me, so I have to work with what I can get locally.

----------------------

A non entity

You, Sir, are well on your way to doing everything to the best of your ability. Reading everything, picking out the details, applying it all by hand... bravo. I agree with you. 100%


The round disks I used on the Warning Light delete are 16g galvanneal. Maybe I preped them totally incorrectly, idk. But the primer stuck.

The bulkhead is much thinner (20g?) and warped from the factory screws (4ea.) that held the warning lights.

The 16g patches, mounted inside w/ 6 rivets, pulled it all flat again. For me, heavier guage is win, here.

My IC body is built with 16g steel. The roof, however might be 18g. Still, for my AC patch, I used 16g . The patch also bridges two ribs.

Maybe it will all help keep the arch while supporting the 100lb HVAC we chose. I know I didn't want a belly near the hole in the roof.


No fun going up & down re-hooking loose straps. I switched to water in buckets. Hang empty, hose fill.

I used wood to focus the weight above the working rivet. Switched to unistrut on the edge rivets, so I could insert clecos & drill through the channel/slots.

All this and more....
Convert Hatch to AC and Roof Patch
Please document what you do and what you learn.

 

[Albatross]

Of course I didn't think that 16 guage steel is actually bulletproof. I even put a smiley face afterwards, that's how you know it's a joke. :wink1:

Don't these statements contradict each other? Don't worry about coating every thing, but also you should coat everything if you want it to last?

I admitted to being a metal-working newby. Forums like these are where people come to learn and ask "dumb questions." These are the details that I'm trying to figure out. I might be an overthinker, but that comes from a place of recognizing my own ignorance. I have no mentor in this project, and I don't know what I don't know.
I'm pretty sure me living in California has nothing to do with anything mentioned here. Did someone from Cali touch you in the naughty place? IT WASN'T YOUR FAULT! You've got to let it go.

I do not yet have a coating system. I have a can of Rustoleum-equivalent metal primer that I bought from a hardware store. I'm here looking for recommendations on what system & method to use. I was asking about sanding because I was assuming that the instructions on a paint system might not be specific for galvanized or galvanneal. I would think that sanding on top of galvanized might flake off the zinc layer, no? Hence my question about if galvanneal only has a surface layer of zinc. I don't want to sand off the corrosion protection that I paid for.

I'm not referring to the point of entry by the rivet. (I am using Musegenis' & Demac's style of "wet riveting" with seam sealer.) I was referring to the section of new skin that will be outward facing, that will be overlapped by the existing skin. Once the sheet is riveted, this section will be hidden, and no longer be accessible to prime or paint.

I'm sorry for whatever happened to you in California that made you feel so booty tickled. I wasn't defending their policies, and I've only lived here a couple years. I was just adding that as a disclaimer to clarify what was/wasn't available to me. It's a 7 hour drive to get out of state for me, so I have to work with what I can get locally.

It's not cute, and it's not funny, comparing my attitude towards being a sexual assault victim. Especially because it was commiefornians, fleeing the policies they, themselves implemented or allowed to be implemented in their home state, moving to places like where I grew up, that was doing things in a safe, sane, and reasonable way, creating an attractive, natural, and harmonious and affordable way of life and completely destroyed it. I knew a guy that was a descendant of one of the original 300 families that settled Texas that was forced to move because of the invading scourge of socialists. They came in, causing jacked up the prices on everything, and told us how much we were 'doing things wrong', and then proceeded to out-vote the locals on everything, and now the places I grew up look like little San Franshitshow; with homeless, drug addicts, and human feces scattered all over the place between the brand new 'luxury' McCondos built where classic and historical buildings, businesses, and other places of interest used to be. Gay sex in the public streets and alleys, that sort of thing. I left after being called an unreasonable ******* for seeing it coming, and saying that we should do something about it, before we lost the town. And now crime and homelessness is off the charts, mental health and drug addiction is skyrocketing, and the place is insanely expensive to live in, so only the top 10% of the town can afford to live in what used to be nice, middle class housing, while everyone else has been pushed outside.

And you packed up and moved into the fires from whence it came.

The reason I said that your coating largely doesn't matter, is because if you understand how it works--you have a solvent-soaked chemical coating that you spray, brush, or roll on to a piece, and when the solvent evaporates, and eventually 'cures', you wind up with a (mostly) solid mechanical coating applied to a project that protects it from oxidation, water, and various other things depending on the coating itself. Sure, if you're trying to min/max or are OCD/obsessive in the way things are done, you could actually coat each individual piece (ie. brushing/rolling/spraying cut edges) prior to painting the whole, but if you're smart about it, and you are capable of doing a good job, then I wouldn't bother as it's mostly a waste of time, and can throw alignments off by a few mils if measurements like that count.

 

[musigenesis]

@Anon Ent Titty

This site has a very useful feature called the ignore list. Click on "User CP" in the upper left corner, then click "Edit Ignore List". You can then add any users whose comments you wish to block.

This site has a very sensible "no politics" rule, but it's often ignored and not often enforced, which is unfortunate for those of us who come here just to discuss bus conversions. But the ignore list accomplishes almost the same thing.

 

[Johnthebusboy]

You could wash the steel with soap and water using a scotch bride scouring pad. This will remove what ever lubricants on the steel and give it some "tooth".