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12-04-2015, 11:24 PM
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#1
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Mini-Skoolie
Join Date: Aug 2010
Posts: 30
Year: 1986
Coachwork: bluebird
Engine: Int. DT466
Rated Cap: 35
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need help figuring out why my paint failed
I have had a major paint failure and it is boggling my mind. please give me your input if you have any ideas as to why this happened.
i painted over my original school bus yellow with a tractor paint of some kind years ago, it held up great.
then years later, i sprayed a coat of Miller equipment enamel, it held up great for years, but faded quite a bit,
I just put a fresh coat on my bus this summer. over the top of the enamel, i used a clear coat/uv protectant/ hardener called break through by ppg. i sprayed the paint and clear coat. it was august in idaho, warm and dry. i allowed days in between application. everything was perfect..... and then....
just last week i had my bus in the shop. some time between dropping it off and picking it up, this happened:
somehow the paint lifted in a couple spots. whats really crazy is that it lifted past all the previous layers of paint, lifting the original paint all the way to the metal.
it was a heated shop, my first thought was it was directly under a heater for some time and then moved out into 20 degree temp. but the bay that my bus was in doesn't have a heater over it.
there was nothing that came in contact with my bus....liquid, solid etc....
there were a few spots where i didn't feather sand the edge of the existing paint quite enough before spraying, but for this to happen?
if anyone has any ideas please share. thanks
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12-05-2015, 07:40 AM
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#2
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Bus Nut
Join Date: Jan 2015
Location: ...little north of Toronto Ontario
Posts: 606
Year: 2000
Coachwork: Thomsass
Chassis: FreightShaker
Engine: 5.9 Cummins 5 speed
Rated Cap: 2 ATV's and friends
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I'm thinkin' paints were not compatible? Not all paints work together, they can attack each other...you'll get fish eyes, orange peel etc.
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12-05-2015, 08:28 AM
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#3
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Bus Crazy
Join Date: Apr 2013
Location: Colorado
Posts: 2,356
Year: 1993
Coachwork: bluebird
Engine: 5.9 Cummins, Allison AT1545
Rated Cap: 2
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idk, but as a guess, i think thats from contracting and expansion of the metal. too many layers contracting or expanding at different rates.
my 2 cents
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12-05-2015, 08:56 AM
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#4
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Bus Crazy
Join Date: Apr 2014
Location: EHT New Jersey
Posts: 1,134
Year: 2003
Coachwork: AmTran
Chassis: International 3000RE
Engine: T444E/AT545
Rated Cap: 75
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Was the first paint or clear coat an acrylic? Enamels, as a rule of thumb, react differently over acrylics than acrylics over enamels
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12-05-2015, 10:29 AM
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#5
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Mini-Skoolie
Join Date: Aug 2010
Posts: 30
Year: 1986
Coachwork: bluebird
Engine: Int. DT466
Rated Cap: 35
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it just seems odd that those two paints would sit together for years with no problems. i can't remember what the first layer of paint was. but that first layer sat under the enamel for years. and this second layer of enamel sat on top of all that for months. i would think that if paints were going to react, they'd do so within the cure time of the paint.
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12-05-2015, 10:30 AM
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#6
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Mini-Skoolie
Join Date: Aug 2010
Posts: 30
Year: 1986
Coachwork: bluebird
Engine: Int. DT466
Rated Cap: 35
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.....also there was no clear coat under any paint, just on top of the second layer of enamel.
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12-05-2015, 10:36 AM
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#7
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Bus Crazy
Join Date: Nov 2011
Location: Sault Ste. Marie, Ontario
Posts: 1,791
Year: 1997
Coachwork: Thomas
Chassis: B3800 Short bus
Engine: T444E
Rated Cap: 36
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I read your initial post, but the pictures make it look like you painted over galvanized sheet metal. Or perhaps the previous paint was a silver colour? Or the peeling pulled back all layers of the paint to expose galvanized? IDK..
I'm just wondering because the peeling would make perfect sense if the paint was layered over un-prepped galvanized steel..
Probably not, but it's worth ruling out some more options...
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12-05-2015, 02:34 PM
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#8
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Bus Crazy
Join Date: May 2010
Location: Montana
Posts: 1,626
Year: 1995
Coachwork: Blue Bird
Chassis: All-American R/E
Engine: 8.3 Cummins
Rated Cap: 72
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Paint and galvanized dont get along well. It doesnt look like the steel was prepped correctly.
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12-05-2015, 03:00 PM
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#9
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Mini-Skoolie
Join Date: Aug 2010
Posts: 30
Year: 1986
Coachwork: bluebird
Engine: Int. DT466
Rated Cap: 35
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that is the original bus body you're seeing there, not a paint. the peeling pulled off original 1986 bus yellow paint. thats what racks my brain, school bus paint is bomber.
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12-05-2015, 03:13 PM
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#10
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Bus Crazy
Join Date: May 2010
Location: Montana
Posts: 1,626
Year: 1995
Coachwork: Blue Bird
Chassis: All-American R/E
Engine: 8.3 Cummins
Rated Cap: 72
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Guess I've never seen factory steel being galvanized.
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12-05-2015, 04:20 PM
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#11
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Bus Crazy
Join Date: Nov 2015
Location: Billings, MT
Posts: 1,269
Year: 2003
Coachwork: Thomas
Chassis: HDX
Engine: Cat C7
Rated Cap: 84 passenger
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At least you'll have a clean slate for the next coat.
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12-06-2015, 06:59 AM
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#12
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Bus Geek
Join Date: Nov 2011
Location: MNT CITY TN
Posts: 5,158
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Wow, impressive, the chrome yellow is impossible to get off normally
Now when I was removing some stickers on the bus I accidentally razor bladed to deep and it came off in big chunks and the steel was galvanized under it also
My egumikated guess is the new paint chemically soaked up through the layers, encapsulated the paint down to galvinizing and just "popped" loose due to metal shrinking
Something in new paint job must of chemically reacted with galvinizing and just let go of adhesion factor
Can you hit areas with rubber hammer and have more paint pop off?
__________________
Our build La Tortuga
Accept the challenges so that you can feel the exhilaration of victory.
George S. Patton
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12-06-2015, 10:35 PM
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#13
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Bus Nut
Join Date: Sep 2013
Location: Denver
Posts: 489
Year: 1982
Coachwork: Blue Bird
Chassis: International S1800
Engine: DT466 Trans: MT643
Rated Cap: 65
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This ain't nothing to complain about! That metal looks so pristine, at least your not rustin out! I wish my bus was made of galvanized steel. strip all the paint and it'll look like a delorean!
__________________
Patina enthusiast and professional busman
www.bustoshow.org
Blog: www.lookatthatbus.com
Instragram: @lookatthatbus
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12-07-2015, 08:45 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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??? Looks just like galvanized that was not properly etched to begin with. Any kind if paint will let go and come off in big flakes if not.
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12-07-2015, 01:05 PM
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#15
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Bus Crazy
Join Date: Nov 2015
Location: Billings, MT
Posts: 1,269
Year: 2003
Coachwork: Thomas
Chassis: HDX
Engine: Cat C7
Rated Cap: 84 passenger
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Quote:
Originally Posted by charles_m
This ain't nothing to complain about! That metal looks so pristine, at least your not rustin out! I wish my bus was made of galvanized steel. strip all the paint and it'll look like a delorean!
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But, where would you find a flux capacitor big enough?
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12-07-2015, 03:08 PM
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#16
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Mini-Skoolie
Join Date: Feb 2015
Posts: 16
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And how in the devil will it get to 88mph??????
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12-07-2015, 07:55 PM
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#17
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Bus Crazy
Join Date: Apr 2014
Location: EHT New Jersey
Posts: 1,134
Year: 2003
Coachwork: AmTran
Chassis: International 3000RE
Engine: T444E/AT545
Rated Cap: 75
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Quote:
Originally Posted by msumoose
And how in the devil will it get to 88mph??????
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RATO/JATO bottles
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