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 Post subject: Painting Frame
PostPosted: April 2, 2019, 3:05 pm 
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Joined: December 6, 2017, 2:20 pm
Posts: 124
Location: San Jose, California
Hi Guys,

I plan to paint the frame soon. Is there any good steps to follow?

1) Wash the frame with soap/water
2) Acetone
3) Primer (recommended brand?)
4) Paint ( recommended brand)

Is there anything that goes over the paint to prevent chipping or keep it stronger? Clearcoat?


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 Post subject: Re: Painting Frame
PostPosted: April 2, 2019, 3:18 pm 
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Joined: January 10, 2008, 4:47 pm
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Location: Massachusetts
My first recommendation is please don't use black paint. It will hide any cracks that appear. A dark grey still allows you find cracks easily. I've just used Rustoleum. It can be recoated easily for any damage.

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 Post subject: Re: Painting Frame
PostPosted: April 2, 2019, 4:28 pm 
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Joined: February 19, 2012, 8:04 pm
Posts: 13
I'm happy with Rustoleum primer and light gray/silver.


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 Post subject: Re: Painting Frame
PostPosted: April 2, 2019, 4:36 pm 
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Joined: December 6, 2017, 2:20 pm
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Location: San Jose, California
Rustoeium sands good. Is there a process though? Like do I wirebrush the whole frame or is acetone clean up. There is mill scale on some places. Do those need to be removed?


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 Post subject: Re: Painting Frame
PostPosted: April 2, 2019, 6:36 pm 
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Joined: May 27, 2006, 9:46 pm
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Location: BC, Canada. eh?
As I'm about at the same point, I, too, await with bated breath the advice of those who have done this!

I've been told that it's a good idea to use something like Eastwood's "After Blast" (essentially, phosphoric acid) wash on the bare metal after sanding off any rust & prior to paint. Theoretically, it removes all traces of grease etc. and, according to Eastwood, leaves a zinc phosphate coating.

I don't know if it's true or not, and I've read dissenting opinions. I have some, but haven't decided if I should use it or not.

Honestly, I was leaning toward Rustoleum anti-rust primer, followed by Rustoleum anti-rust paint, without any other layers used. My buddy did several coats, using different types of breathtakingly expensive specialty aircraft epoxy paints. I'm sure it will be tough, but repairs (if he needs to sand off a spot to weld on a bracket or something) could be tougher.

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 Post subject: Re: Painting Frame
PostPosted: April 2, 2019, 7:35 pm 
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Joined: July 17, 2008, 9:11 am
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Location: West Chicago,IL
Here is what I did: Wipe down the frame with mineral spirits and then spray the inside, tight corners with spray cans of Gray Rustoleum ( the good stuff) while rolling the same color Rustoleum with a foam 4" roller where you didn't spray. That should get Rustoleum everywhere. Done.

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 Post subject: Re: Painting Frame
PostPosted: April 2, 2019, 8:04 pm 
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Joined: January 31, 2012, 12:49 pm
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Location: Louisville KY
Seems to me that a wipe down to remove dirt, welding dust and surface rust is appropriate. Then priming that includes an etching of the metal so that the paint bonds well?

I did the Rust-oleum rust remover liquid a couple of times to do both cleaning and etching. Then self-etching primer. Haven't gotten to the final coat yet, but anticipate it to be grey (or light enough to show cracks when they develop).

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 Post subject: Re: Painting Frame
PostPosted: April 2, 2019, 9:08 pm 
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Joined: January 11, 2017, 11:06 pm
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Location: Alberta
For me, I really wanted to get that oxide layer off the steel before painting. I don't mean rust, just that flaky scale from the mill. Thus, I took the frame to an outdoor sandblasting site and for about $100 blasted the whole frame. I then coated it with rolled-on POR-15, and finished with POR-15 topcoat from a rattle can. Unfortunately I went with black; didn't know about it hiding cracks. I will have to carefully check the frame at the end of each season. In any case, I have had to grind the paint off some areas to add a little bracket or tab here and there, and it has proven very difficult to remove - even with a flap disc. I think that is a good sign that it will stand up well.

One other thing - POR15 is not UV-stable on its own, which is why I sprayed the top coat. I also used POR-15 roll-on bedliner on the underside of the car and in the footwells for added wear resistance.


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 Post subject: Re: Painting Frame
PostPosted: April 2, 2019, 9:12 pm 
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Joined: December 18, 2010, 3:29 pm
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So getting paint to stick to new steel can go badly sometimes. A trick my farmer FIL taught me was to hit new, bare steel with a rosebud or big tip oxy torch before painting, same with freshly sandblasted steel. You can see it sweat out moisture which makes sense but I think that moisture carries some oils with it (this is one my engineer brain struggles to make sense of but it just works, every time). I have had incredible luck by cleaning with soap and water, acetone, torch until it stops oosing moisture (you can move at 1ft/2sec or so, it's not a slow process, you can watch the moisture front evaporate fast), acetone one more time, then primer. I've skipped the second acetone a few times with no issues either. Plus, then you're painting warm steel which I also think helps.

Alex


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 Post subject: Re: Painting Frame
PostPosted: April 2, 2019, 9:28 pm 
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Joined: January 31, 2012, 12:49 pm
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Location: Louisville KY
Can't we do it the old Brit way? Historical accuracy? Make sure it sits in inventory until the bare metal has started to rust, ship it for 6 weeks to insure salt air exposure, then make sure the engine leaks enough oil to cover the underside w/ a non-rust coat of oil?

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 Post subject: Re: Painting Frame
PostPosted: April 2, 2019, 9:29 pm 
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Joined: June 13, 2014, 11:55 am
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Just make sure your torch is extinguished before you fire your air gun.
It may sound stupidly basic, but I have heard horror stories...


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 Post subject: Re: Painting Frame
PostPosted: April 3, 2019, 8:36 am 
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ajmacdon wrote:
So getting paint to stick to new steel can go badly sometimes. A trick my farmer FIL taught me was to hit new, bare steel with a rosebud or big tip oxy torch before painting, same with freshly sandblasted steel. You can see it sweat out moisture which makes sense but I think that moisture carries some oils with it (this is one my engineer brain struggles to make sense of but it just works, every time). I have had incredible luck by cleaning with soap and water, acetone, torch until it stops oosing moisture (you can move at 1ft/2sec or so, it's not a slow process, you can watch the moisture front evaporate fast), acetone one more time, then primer. I've skipped the second acetone a few times with no issues either. Plus, then you're painting warm steel which I also think helps.

Alex


Alex, I believe that this is not true, At least not enough to ne noticeable by the naked eye. The byproduct of the torch's flame is CO2 and H20. The H2O condenses on the cold steel when torch is first applied. Then as the steel warms up, the water no longer condenses and instead, the water that had just condensed on the steel evaporates. Steel does not absorb water nor is it porous. Your farmer FIL was misled. All is not lost though. The heated steel may have helped dry the paint slightly quicker.

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“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE


Last edited by rx7locost on April 3, 2019, 9:39 am, edited 2 times in total.

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 Post subject: Re: Painting Frame
PostPosted: April 3, 2019, 8:47 am 
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Joined: August 31, 2015, 2:24 pm
Posts: 169
Location: Delaware
I just painted mine last weekend, black (oh well). I used VHT Chassis and roll bar as it is a straight to metal epoxy based finish. It's still curing according to the can. The process was use a wax and grease remover, remove loose surface stuff with a red 3m (Scotchbrite) pad and then wax and grease remover again and spray. Pepboys local carried both the Dupli-color wax and grease remover which is easier to work with than acetone since it doesn't evaporate as fast and the VHT stuff. I used 6 cans of VHT and probably could have used one more but that's all they had. The finish looks good so far although the VHT cans seem to have a limited number of spray button cycles before it stops spraying.


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 Post subject: Re: Painting Frame
PostPosted: April 3, 2019, 2:40 pm 
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Location: Louisville KY
rx7locost wrote:
The heated steel may have helped dry the paint slightly quicker.


Would burn off a bunch of garf too.

The mill scale actually will stick to the steel as long as you need it to, but the question at that point is whether the paint sticks to mill scale?

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 Post subject: Re: Painting Frame
PostPosted: April 3, 2019, 2:43 pm 
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Joined: December 18, 2010, 3:29 pm
Posts: 96
rx7locost wrote:
ajmacdon wrote:
So getting paint to stick to new steel can go badly sometimes. A trick my farmer FIL taught me was to hit new, bare steel with a rosebud or big tip oxy torch before painting, same with freshly sandblasted steel. You can see it sweat out moisture which makes sense but I think that moisture carries some oils with it (this is one my engineer brain struggles to make sense of but it just works, every time). I have had incredible luck by cleaning with soap and water, acetone, torch until it stops oosing moisture (you can move at 1ft/2sec or so, it's not a slow process, you can watch the moisture front evaporate fast), acetone one more time, then primer. I've skipped the second acetone a few times with no issues either. Plus, then you're painting warm steel which I also think helps.

Alex


Alex, I believe that this is not true, At least not enough to ne noticeable by the naked eye. The byproduct of the torch's flame is CO2 and H20. The H2O condenses on the cold steel when torch is first applied. Then as the steel warms up, the water no longer condenses and instead, the water that had just condensed on the steel evaporates. Steel does not absorb water nor is it porous. Your farmer FIL was misled. All is not lost though. The heated steel may have helped dry the paint slightly quicker.


Oh, trust me, I'm fully aware of the combustion chemistry and all the reasons this should be total BS. However, even with full cooling before painting I've had the paint stick significantly better than fresh metal I've painted without the torch step.

Maybe it's just burning off any oil left after the acetone wipe? I've searched my science based soul for a reason this should work and, like you, that part of my brain calls BS. More than one engineer has been burned by not listening to the farmer, though.

Alex


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