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04-26-2017, 10:00 PM
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#1
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Bus Nut
Join Date: Oct 2015
Posts: 340
Year: 2003
Chassis: E-450
Engine: 7.3 Turbo
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To treat or not to treat (new galv steel)
Here's an interesting one for you guys...
We're replacing the entire metal floor. The last few days have been spent scraping up all the old adhesive that kept the original steel down.
So we have new steel that we plan on putting down in the next couple days.
The question is, should we put rustoleum down or just let it go?
And before you say to just put the paint down, new galvanized steel can be a real pain as far as getting paint to actually stick for long periods (think ~5 years). I have no way of knowing how long its been weathered.
What would you do?
Also, there will be undercoating going on from below.
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04-26-2017, 10:16 PM
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#2
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Bus Geek
Join Date: Mar 2011
Location: Houston, Texas
Posts: 8,462
Year: 1946
Coachwork: Chevrolet/Wayne
Chassis: 1- 1/2 ton
Engine: Cummins 4BT
Rated Cap: 15
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You cannot get paint to adhere to galvanized without etching it first. Properly etched and painted, it will last much longer than unpainted.
PS...there are also "Self Etching Primers" out there.
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04-26-2017, 10:32 PM
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#3
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Bus Geek
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,764
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
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Use Ospho to etch galvanized steel, then its paintable.
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04-26-2017, 10:49 PM
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#4
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Bus Nut
Join Date: Oct 2015
Posts: 340
Year: 2003
Chassis: E-450
Engine: 7.3 Turbo
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****, all you need to do is etch it? Okay then, I stand corrected! Thanks guys.
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04-26-2017, 11:09 PM
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#5
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Bus Geek
Join Date: Feb 2016
Location: Willamina, Oregon
Posts: 6,409
Coachwork: 97 Bluebird TC1000 5.9
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Does muratic acid work for that? I know they use it on unpainted metal roofing before they paint it.
__________________
Robin
Nobody's Business
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04-27-2017, 05:29 AM
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#6
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Bus Geek
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,764
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
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Quote:
Originally Posted by Robin97396
Does muratic acid work for that? I know they use it on unpainted metal roofing before they paint it.
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I'm sure it would, but its real nasty stuff. Especially inside a closed area.
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04-27-2017, 08:03 AM
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#7
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Bus Nut
Join Date: Oct 2015
Posts: 340
Year: 2003
Chassis: E-450
Engine: 7.3 Turbo
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I'm pretty sure that muriatic acid should NOT be used on anything galvanized. It will strip the zinc off completely.
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04-27-2017, 09:23 AM
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#8
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Bus Geek
Join Date: Feb 2016
Location: Willamina, Oregon
Posts: 6,409
Coachwork: 97 Bluebird TC1000 5.9
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When someone builds a big barn they often wash the metal with muratic acid before painting. It's readily available at any pool supply store.
I've never used it myself. That is what people used before there were all these etching paints and stuff.
__________________
Robin
Nobody's Business
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04-27-2017, 09:39 AM
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#9
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Skoolie
Join Date: Aug 2016
Posts: 216
Year: 1999
Coachwork: Thomas
Chassis: Saf-T-Liner MVP ER
Engine: CAT 3126
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Why not go stainless?
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04-27-2017, 09:52 AM
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#10
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Bus Nut
Join Date: Jan 2015
Location: Kansas
Posts: 492
Year: 2000
Chassis: International 3800
Engine: T444E
Rated Cap: Your mom +1
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probably because galv steel is half the cost of SS... and I'm guessing they're not made of money...
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04-27-2017, 10:21 AM
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#11
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Bus Nut
Join Date: Oct 2015
Posts: 340
Year: 2003
Chassis: E-450
Engine: 7.3 Turbo
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Quote:
Originally Posted by slaughridge85
probably because galv steel is half the cost of SS... and I'm guessing they're not made of money...
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Ding ding ding! We really didn't want to replace it at all, but the stuff in the bus to start was paper thin. I pretty much destroyed it getting the plywood up, so there was no option.
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04-27-2017, 10:23 AM
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#12
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Bus Geek
Join Date: Mar 2011
Location: Houston, Texas
Posts: 8,462
Year: 1946
Coachwork: Chevrolet/Wayne
Chassis: 1- 1/2 ton
Engine: Cummins 4BT
Rated Cap: 15
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I use muriatic to clean the mill scale off of hot rolled steel and it is seriously NASTY stuff to work with. It can, however, be diluted and used to etch galvanized. Full strength it would be far too aggressive. Personally, I stick with "Self-Etching" primer for that sort of thing.
One other issue...anytime you do use muriatic...you MUST use a "stop bath" to prevent continued etching and rust. Baking soda and water will stop the acidic action. Big PITA as the soda must be thoroughly cleaned off before painting.
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04-27-2017, 10:26 AM
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#13
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Bus Nut
Join Date: Oct 2015
Posts: 340
Year: 2003
Chassis: E-450
Engine: 7.3 Turbo
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I've done as much researching as I care to do at this point. Here is what I've found. Please correct me if you think I'm wrong...
Muriatic acid will remove all of the galvanized coating. (Tango just commented above, sounds like you can use it diluted)
Phosphoric acid (Ospho) is a better choice if you want to keep it.
After using Ospho, the ideal primer will be a high-zinc formulation.
I don't want to spend all day looking for high-zinc primer, so I'll probably just go with rustoleum unless it happens to be easy to get and cheap.
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04-27-2017, 10:30 AM
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#14
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Bus Geek
Join Date: Mar 2011
Location: Houston, Texas
Posts: 8,462
Year: 1946
Coachwork: Chevrolet/Wayne
Chassis: 1- 1/2 ton
Engine: Cummins 4BT
Rated Cap: 15
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Most all auto parts stores sell rattler cans of self etching primer. Cheap, easy fix for galvanized and aluminum (which also must be etched first).
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04-27-2017, 10:32 AM
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#15
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Bus Nut
Join Date: Oct 2015
Posts: 340
Year: 2003
Chassis: E-450
Engine: 7.3 Turbo
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Quote:
Originally Posted by Tango
Most all auto parts stores sell rattler cans of self etching primer. Cheap, easy fix for galvanized and aluminum (which also must be etched first).
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How many cans for 120 sq feet do you think?
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04-27-2017, 11:23 AM
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#16
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Bus Geek
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,764
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
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Quote:
Originally Posted by PigPen
I'm pretty sure that muriatic acid should NOT be used on anything galvanized. It will strip the zinc off completely.
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I've used it on HUGE boats before.
I HATE working with muriatic acid, bad.
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04-27-2017, 11:25 AM
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#17
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Bus Geek
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,764
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
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Quote:
Originally Posted by PigPen
I've done as much researching as I care to do at this point. Here is what I've found. Please correct me if you think I'm wrong...
Muriatic acid will remove all of the galvanized coating. (Tango just commented above, sounds like you can use it diluted)
Phosphoric acid (Ospho) is a better choice if you want to keep it.
After using Ospho, the ideal primer will be a high-zinc formulation.
I don't want to spend all day looking for high-zinc primer, so I'll probably just go with rustoleum unless it happens to be easy to get and cheap.
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Ace sells zinc oxide primer, but after ospho Rustoleum sticks fine. I've done the entire inside of my ceilings with Ospho and Rustoleum- and it GOOD.
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04-27-2017, 12:17 PM
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#18
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Bus Nut
Join Date: Mar 2016
Location: Greater Houston, Tx.
Posts: 589
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Ospho goes on really thin, so I bet you can do the whole bus with 1 gal.
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04-27-2017, 12:34 PM
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#19
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Bus Nut
Join Date: Oct 2015
Posts: 340
Year: 2003
Chassis: E-450
Engine: 7.3 Turbo
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I have to remember to go to ace more. Home depot and lowes consistently disappoint me in selection and quality, meanwhile ace always has what I need.
Long story short, I got ospho and special primer (happened to be $8 off today which I'm happy about), plus they have solar flex which no one else seems to around here.
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04-27-2017, 12:42 PM
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#20
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Bus Geek
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 23,764
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
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Quote:
Originally Posted by 1olfart
Ospho goes on really thin, so I bet you can do the whole bus with 1 gal.
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Absolutely. I've been using it HEAVILY on my build, and I've still got a half gallon. Thin isn't even the word- its the same viscosity as water, and goes on like water. On areas that aren't rusty and I just want to etch, I dilute with distilled.
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