Reply
 
Thread Tools Display Modes
 
Old 05-11-2020, 09:23 PM   #21
Skoolie
 
Join Date: Oct 2018
Location: Central Alabama
Posts: 127
Year: 1998
Coachwork: Blue Bird
Chassis: TC/2000
Engine: 5.9 Cummins 12-valve
Rated Cap: 1
Can moisture from an air tank cause issues with the finish spray?
BamaBus is offline   Reply With Quote
Old 05-11-2020, 09:58 PM   #22
Bus Crazy
 
banman's Avatar
 
Join Date: Aug 2019
Location: Ohio
Posts: 1,495
Year: 2002
Coachwork: Thomas
Chassis: Freightliner FS-65
Engine: 7.2L Cat 3126 turbo diesel
Rated Cap: 71 passenger 30,000 gvwr
Quote:
Originally Posted by BamaBus View Post
Can moisture from an air tank cause issues with the finish spray?
Absolutely! Just assumed the OP was using an inline filter before the paintgun.
__________________
David

The Murder Bus
banman is offline   Reply With Quote
Old 05-11-2020, 10:11 PM   #23
Bus Geek
 
Join Date: May 2016
Location: Eastern WA
Posts: 6,363
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
Quote:
Originally Posted by Danjo View Post
What kind of cloth and what was the grease remover?
Microfiber and T-shirt all fresh out of the laundry.
PNW_Steve is offline   Reply With Quote
Old 05-11-2020, 10:42 PM   #24
Bus Geek
 
Join Date: May 2016
Location: Eastern WA
Posts: 6,363
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
I purged my tank and added an inline air dryer/filter before I started.
PNW_Steve is offline   Reply With Quote
Old 05-11-2020, 10:42 PM   #25
Skoolie
 
Join Date: Jul 2015
Location: Vermont
Posts: 147
Year: 1996
Coachwork: Turtle Top
Chassis: E-Super Duty
Engine: Ford 7.3 Powerstroke
Rated Cap: 13-passenger
Quote:
Originally Posted by sproutroot View Post
Make sure that air hose is clean. You may want to just cover it with something for this job. They get dragged through every project you use them for, so they're usually soaked with all kinds of oils and metal dust.
I'd probably even wear shoe covers to prevent contamination during the painting process.
sproutroot is offline   Reply With Quote
Old 05-11-2020, 11:00 PM   #26
Bus Crazy
 
Join Date: Sep 2018
Posts: 1,466
Year: 2007
Coachwork: Thomas Built
Chassis: Minotour
Engine: Chevy Express 3500 6.6l
What are you using to sand? Is it a vibratory sander? Is the paper wearing out to the backing on the sander?
Danjo is offline   Reply With Quote
Old 05-12-2020, 08:16 AM   #27
Bus Nut
 
ACamper's Avatar
 
Join Date: Sep 2017
Location: Colorado
Posts: 374
Did you use primer ? To me it looks like it needs a primer.
ACamper is offline   Reply With Quote
Old 05-12-2020, 09:24 AM   #28
Bus Nut
 
TheHubbardBus's Avatar
 
Join Date: Apr 2019
Location: Hotzona
Posts: 934
Year: 2003
Coachwork: IC
Chassis: 3800
Engine: Navistar T444e
Rated Cap: 24
Maybe my eyes or the picture, but I'm having a hard time seeing how something like that could even happen out of a spray gun. Those weird random patterns look like someone took a tree branch to your paint.



Any chance contaminates could have been dropped in the paint? Or that you hadn't thoroughly mixed it?
__________________
-Sharon & Jody
Mr Beefy Short Bus Acquisition & Build Thread
TheHubbardBus is offline   Reply With Quote
Old 05-12-2020, 09:47 AM   #29
Bus Geek
 
Join Date: May 2016
Location: Eastern WA
Posts: 6,363
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
Yeah, it does look like someone drug a tree branch across the paint.

It occurred primarily in three spots. Not the whole roof.

Spots that we sanded through the existing paint got primer. Some small round spots and rivet heads.

There has not been much opportunity for contamination.

It's a mystery... Now, what to do about it? I can send it and shoot it again but I have no indication that the results will be different.
PNW_Steve is offline   Reply With Quote
Old 05-12-2020, 10:11 AM   #30
Bus Nut
 
TheHubbardBus's Avatar
 
Join Date: Apr 2019
Location: Hotzona
Posts: 934
Year: 2003
Coachwork: IC
Chassis: 3800
Engine: Navistar T444e
Rated Cap: 24
I don't see how you could do that twice, Steve Whatever stars aligned to make that happen likely won't the second time around. The frustration, of course, would be still not knowing what caused it.

In most cases, I think you'd want to prime the entire surface, whether it was down to metal or not, unless you know that both the old paint & new are compatible.

I've been recently warned by the gent who repaired our cap dents to never use silicone, as it interferes with paint adhesion even after being removed from old paint. He claims that even bringing it down the metal may not be enough without thorough prep. Could those strange patterns be splatter-marks from some chemical compound that at some point got dropped/splashed/applied to those areas, soaking into the old paint?

If it were me, I'd bring those spots down to metal, prep, prime & go again.
__________________
-Sharon & Jody
Mr Beefy Short Bus Acquisition & Build Thread
TheHubbardBus is offline   Reply With Quote
Old 05-12-2020, 10:41 AM   #31
Bus Crazy
 
Join Date: Sep 2018
Posts: 1,466
Year: 2007
Coachwork: Thomas Built
Chassis: Minotour
Engine: Chevy Express 3500 6.6l
To me it looks like a kid drew on it with a crayon. That’s why I think contamination on the sander. When I was sanding with my electric orbital sander I noticed that when the edges of the paper wore, the backing pad would mark the surface.
Danjo is offline   Reply With Quote
Old 05-12-2020, 11:32 AM   #32
Skoolie
 
Join Date: Oct 2018
Location: Central Alabama
Posts: 127
Year: 1998
Coachwork: Blue Bird
Chassis: TC/2000
Engine: 5.9 Cummins 12-valve
Rated Cap: 1
I couldn't see the pics that well on my phone but after looking again I don't think it was a liquid. It looks to skip over and on top of the rivets which would leave me to think it was something dragging or rubbing. Is this just on the top or has some paint been applied to the sides?
BamaBus is offline   Reply With Quote
Old 05-12-2020, 03:49 PM   #33
Skoolie
 
Join Date: Jan 2020
Location: Ohio
Posts: 144
Year: 2008
Coachwork: Thomas
Chassis: 0908S
Engine: Cummins 5.9
Rated Cap: 28' 9 window
Did you clean the surface with acetone? Id try that in a different area
dwood443 is offline   Reply With Quote
Old 05-12-2020, 04:17 PM   #34
Bus Crazy
 
Join Date: May 2014
Location: West Ohio
Posts: 1,832
Year: 1984
Coachwork: Bluebird
Chassis: International 1753
Engine: 6.9 International
Rated Cap: 65
Are you sure the sher-kem can be applied over your existing paint? It says direct to metal on the website.

If paint is retreating, typically it's from some sort of contaminant. Whether it was on the surface and your prep didn't get to it, or it was put on after the prep, or is something inside the gun.

I like the hose dragging thought. I could see that happening easily.

I know when we painted mine we ran into that issue as well. I also had to paint the roof in my socks because no amount of cleaning of my boots would get the soles clean enough not to leave a mark on the prepped surface.

To fix it. I'd sand it back to the yellow. Wipe it with paint thinner and a lint free rag, then spray it with acetone and let that air dry.

Then shoot your paint on just those spots and see what happens.
__________________
The Silver Bullet https://www.skoolie.net/forums/f11/p...llet-9266.html
Booyah45828 is offline   Reply With Quote
Old 05-13-2020, 08:06 AM   #35
Skoolie
 
Join Date: Jul 2015
Location: Vermont
Posts: 147
Year: 1996
Coachwork: Turtle Top
Chassis: E-Super Duty
Engine: Ford 7.3 Powerstroke
Rated Cap: 13-passenger
remember that perfect prep will really suck the contaminants out of your surface leaving the pores wide open. it doesn't take much to screw up this surface. if a contaminant is introduced after prep, it will be a lot more potent than if the same contaminant had been introduced beforehand. the pores will eat it up.

I agree with what others have said, sand it down to bare metal and reprep. I would tape clean rags around the air hose wherever it'll touch the roof. I think that's more practical than trying to clean it. serious painters even have dedicated hoses for painting (mostly to avoid contaminants on the inside of the hose, actually). that's not my style, but it's probably the best way to keep things clean.

I'm sorry this happened, man. for what it's worth, you don't have to fix it if you don't want to.
sproutroot is offline   Reply With Quote
Old 05-13-2020, 12:06 PM   #36
Bus Geek
 
Join Date: May 2016
Location: Eastern WA
Posts: 6,363
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
Quote:
Originally Posted by TheHubbardBus View Post
I don't see how you could do that twice, Steve Whatever stars aligned to make that happen likely won't the second time around. The frustration, of course, would be still not knowing what caused it.

In most cases, I think you'd want to prime the entire surface, whether it was down to metal or not, unless you know that both the old paint & new are compatible.

I've been recently warned by the gent who repaired our cap dents to never use silicone, as it interferes with paint adhesion even after being removed from old paint. He claims that even bringing it down the metal may not be enough without thorough prep. Could those strange patterns be splatter-marks from some chemical compound that at some point got dropped/splashed/applied to those areas, soaking into the old paint?

If it were me, I'd bring those spots down to metal, prep, prime & go again.
You are preaching to the choir I don't allow silicone within 10'of the bus.

As far as paint compatibility, I checked with SW and I am good there.

I cannot see any contamination occurring during or after my prep. There just is no opportunity where the bus is.

The alternative is that I failed to remove contamination that was preexisting. If that is the case, what to do after washing twice, dreading twice and sanding with 120grit on a DA sander?
PNW_Steve is offline   Reply With Quote
Old 05-13-2020, 12:34 PM   #37
Bus Geek
 
EastCoastCB's Avatar
 
Join Date: Sep 2014
Location: Eustis FLORIDA
Posts: 22,468
Year: 1999
Coachwork: Thomas
Chassis: Freighliner FS65
Engine: Cat 3126
Rated Cap: 15
I'd go for like a 220 grit. No need to go to metal if its compatible with the paint.
Its just a total pita to get ALL the surface decontaminated and keep it that way.
I say just sand the area down and wash it and rise it like hell and try again. Make sure its all bone dry before reapplying.
__________________
.
Roll Your Own Build Thread
EastCoastCB is offline   Reply With Quote
Old 05-14-2020, 06:37 AM   #38
Skoolie
 
Join Date: Jul 2015
Location: Vermont
Posts: 147
Year: 1996
Coachwork: Turtle Top
Chassis: E-Super Duty
Engine: Ford 7.3 Powerstroke
Rated Cap: 13-passenger
I just have one more question on my air hose contamination theory. I'm still assuming you were walking backwards while painting, so the air hose wouldn't have ever touched the first 3 or 4 feet that you painted. Is there any of this pattern going on in that area?

If you have no faith that the second try will work, do the first coat in small sections. 4x4, 4x8, something manageable. IF the contamination is getting introduced while painting, this will help a lot. On the other hand, if you're correct and there's something that you aren't getting off during prep - at least you didn't do the whole dang bus again.
sproutroot is offline   Reply With Quote
Old 05-14-2020, 07:58 AM   #39
Bus Geek
 
Join Date: May 2016
Location: Eastern WA
Posts: 6,363
Year: 2002
Coachwork: Bluebird
Chassis: All American RE (A3RE)
Engine: Cummins ISC (8.3)
Rated Cap: 72
Quote:
Originally Posted by sproutroot View Post
I just have one more question on my air hose contamination theory. I'm still assuming you were walking backwards while painting, so the air hose wouldn't have ever touched the first 3 or 4 feet that you painted. Is there any of this pattern going on in that area?

If you have no faith that the second try will work, do the first coat in small sections. 4x4, 4x8, something manageable. IF the contamination is getting introduced while painting, this will help a lot. On the other hand, if you're correct and there's something that you aren't getting off during prep - at least you didn't do the whole dang bus again.
Good suggestions.

But, I have already taken action. I hope it works

I took the bad spots down to bare metal. As soon as the rain stops I am going to prime the bare spots and shoot another coat of paint.
PNW_Steve is offline   Reply With Quote
Old 05-20-2020, 05:35 PM   #40
Mini-Skoolie
 
Join Date: Oct 2018
Location: Canada BC West Kootenays
Posts: 17
Year: 2004
Engine: T444E
Rated Cap: 66
Hi Steve

I was a professional automotive paint for 20 years. You have what they call "fish-eye" That means when you washed it with a wax and grease remover you probably didn't change rags and the silicone, wax, grease worked to the edge of the cloth-making streaks of the contaminate. When you do your wipe down with a wax/grease remover you need to use a wet rag and a dry rag change up your clothes with a new one every so often, and most important you MUST use a dry cloth and dry the wiped spot don't let the solvent dry on the bus roof that's where the contaminates concentrate. Also use loads of the solvent to break the wax and grease up making sue to dry it after. To fix the problem let the coat of paint you have on it dry completely, 24 hrs. Then Scuff it (the streaks) with a fine sand paper to knock down the edges of the "fish-eye". ( Then wash again with wax and grease remover, but lightly this time with clean rags. Your first coat of paint should go really light so it dries quickly, this will bridge any residue left. Let it dry, at least 30 minutes then another light coat and again 30 to 60 minutes. Dry to the touch using the knuckle of your finger, then you can put on a thrid wet coat on for shine this should solve the problem. Happens all the time.

I don't agree with air contamination or hose dragging the look is completely different. I am confident in my analysis of the problem. I have seen it happen many times in my 20 years as a refinisher.

Cheers
__________________
Bud-Brother
BC West Coast Canada
Budbrother is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 07:09 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
×