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An Old, Failed, Paint Job - Why Did it Fail?


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Hello Everyone. I bought my 1926 Dodge Brothers a few years ago. The paint was bad then and keeps getting worse. A lot of cracking and flaking straight to bare metal. 

 

I didn’t get a history on the vehicle, so as to when it was painted is anyone’s guess. The sections that actually haven’t failed aren’t so bad. But here’s what some of the worst sections looks like:

 

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My guess would be poor prep and/or poor storage. Probably a combination of both. What do you guys think? 
 

Also, besides a complete repaint. ( Which I will do some day in the future.) I am trying to think of  what to do to protect these bare steel surfaces. It was suggested to use boiled linseed oil to seal the surface temporarily. Which would include reforming the rust to a neutral state, and then sealing the surface. I’ve thought of touch up paint as an option, but I don’t know if all those odd patches of off color gloss-black would look better or worse than patches of “patina”. Thoughts? 

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Poor prep and wrong product most likely, little impact caused by storage. Does not appear to have used primer, and paint used may not have been intended for this purpose. A good scraping followed by anything that looks presentable will do for now, even a thinned brush on material like black tremclad/rustoleum. can't look worse! Such products can adhere over minor rust.

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There may have been nothing really wrong with the paint job depending on how old it is.   It does look like the primer is having an adhesion to metal problem.  It is not impossible that the metal was not properly metal etched or that it attracted a bit of moisture before it was applied.  it was put on.  Depending on the type of paint it may have just gotten old and brittle.  Eastwood makes a coating to protect bare metal which would help but it won't last forever.   Using something like this would be easier to deal with when you had to take it off to prep for paint.

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If the vehicle has good storage now, I would not really concern myself with protecting the metal for a few years until you are ready for a paint job. If the car stays dry or gets dried off relatively quickly after being caught in the rain, the metal will not rust significantly. Water does get behind the flaking paint and touch up attempts can create a pocket to hold some moisture. Wax it, wd40 it... I wouldn’t do anything that makes the eventual stripping process more complicated. 

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I agree with all the advice you have been given. Poor preparation of surface and applying primer over it did not see the proper adhesion of the primer to the metal . So you won't  duplicate work I would start the "repaint" now. Do a small section at a time ,  Perhaps a door post at a time , when they are done then a larger flat sheet metal door panel. Get ti down to bare metal, sand properly and prime , then paint. You can spray a small area by using a "door jamb spray gun" to apply the paint.

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I think nickelroadster is spot on. This is probably an old acrylic or enamel that’s just continued to harden over time and there has been an adhesion failure at the primer. Unfortunately a more definitive answer will be hard as paint failures can be hard to diagnose unless you’re standing in front of them. I’ll add another cause though as it could equally be the primer had gone past the overcoat window before the top coat was applied and there wasn’t a good bond. Over the years the top coat got harder and stress in the paint pulled it away. Given the cracks in the paint it has been stressed at some point through the years by its curing.
The unusual patterns in the first 2 photos where the top coats are missing does look like there maybe a little grey primer remaining on the surface though, which is good thing in terms of preservation as there is still some paint remaining.
To save yourself problems and time later I would also not recommend using an oil or a wax to protect it. Depending on how much you plan to use the car and where you have to store it, the do nothing option may be the best approach here. The corrosion rate should be low unless you plan to drive on salted roads, live next door to a surf beach or plan to store the car outside in the rain or snow. So enjoy it for the next few years and plan to paint it again sooner rather than later.

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Boiled linseed oil has many uses; however, under certain conditions, spontaneous combustion could occur.   Here's a short cautionary tale from Wikipedia:

Spontaneous combustion

Rags soaked with linseed oil stored in a pile are considered a fire hazard because they provide a large surface area for rapid oxidation of the oil. The oxidation of linseed oil is an exothermic reaction, which accelerates as the temperature of the rags increases. When heat accumulation exceeds the rate of heat dissipation into the environment, the temperature increases and may eventually become hot enough to make the rags spontaneously combust.[49]

In 1991, One Meridian Plaza, a high rise in Philadelphia, was severely damaged and three firefighters perished in a fire thought to be caused by rags soaked with linseed oil.[50]

 

As with many things, potentially hazardous materials or processes, if properly handled, can be relatively safe, otherwise, not so much.

 

Be careful out there.

 

Cheers,

Grog

 

 

 

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Lacquer will crack like this over time if not prepped properly or had been waxed  to soon. 

Back in the early to mid 1970s there was a primer / sealer (I believe it was Ditzler #1970)  that the bond failed after a few years and would look like this.

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Thanks for the replies everyone. The car is garaged as of this week. It has lived in Southern California weather under a tarp for the last 3 years, which no doubt accelerated the failure. From now on it should be garaged with possible outdoor stints in the future.

 

I’ve seen a lot of negative comments on the boiled linseed oil throughout different internet communities, so that option will be ( most likely) getting nixed. 

I think the easiest thing to do at the point is neutralize the rust and add paint. (Or just do the WD40 method, but that might attract dust, no?) My funds are limited so I’m not sure if I want to use rattle cans or invest in the aforementioned door jamb sprayer. ( I do have an air compressor for my air tools, so I could buy a paint gun) 

 

 

6 hours ago, Tim in NC said:

DB26,

Can you remove one of the paint flakes and show us the backside side so we can see if primer is attached to the black paint?

Yes, I will do that. 

Edited by DB26 (see edit history)
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I think some are thinking too modern here - looks like old lacquer applied way too thick over a badly prepared surface then left outside. If you have it garaged no rush to cover the metal until you have an overall strategy.

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On 2/24/2020 at 2:52 AM, Tim in NC said:

DB26,

Can you remove one of the paint flakes and show us the backside side so we can see if primer is attached to the black paint?

Here is the photo of two chips. They were tricky to get because all the chips broke into a million pieces. Here is the front and back of the same two chips. I don’t see primer

 

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Thanks. Looks like you will need to start over from bare metal. And the first coat should be a primer/sealer preferably of the 2-part type like epoxy sealer or what they call 2K. See your local paint supplier to see what they have. 

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1 hour ago, DB26 said:

Here is the photo of two chips. They were tricky to get because all the chips broke into a million pieces. Here is the front and back of the same two chips. I don’t see primer.

 

I agree that primer is not present,  which translates into paint delamination occurring far, far sooner than if primer had been applied, and I don't believe the painter was experimenting with a formulation that combined primer and topcoat as one.

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If I had to guess, a very amateurish paint job. No primer, combined with getting in a hurry and using too fast a thinner in lacquer paint for the temp conditions when sprayed. That builds up a lot of shrinkage tension in the paint film surface that is certain to cause cracking and curling later on as that overcomes the poor adhesion of no proper primer. Seen it too many times in back yard restorations and body shops looking for a quick buck.  

 

Paul

Edited by PFitz (see edit history)
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The good thing is that when you get around to doing it right, a razor blade, or some other scraping tool, should get the job done quickly. Also if you're into doing a quick and dirty blend, it will quickly tell you where there is no adhesion. As if you really had a problem figuring it out.

 

Bill

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You can buy a good gravity feed paint gun (HVLP) at Harbor Freight for $9.99 .After it's bare metal an swiped with Metal Prep, spray the Epoxy Primer.

The primer will separate all the new bondo and paints fron the old metal & paint.  Learn to paint with primer, it's very forgiving.

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the problem with the wd40 suggestion is that it does not play nicely with applying new paint.research before opening a can of worms due to the silicone

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