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I need some help painting a Zamak shell

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I need some help painting a Zamak shell
Posted by RR_Mel on Friday, August 14, 2015 3:29 PM

I need some help painting a Zamak shell
 
I’m not beginner by any means, I’ve been painting my models with an airbrush for more than 30 years.  I have run into a Zamak Cary E7A body that won’t except paint.  Everything I’ve tried has failed.  I’ve tried Automotive primer, Self Etching Primer, Zinc Chromate Primer, Tru-Color Primer soaking it in Vinegar, roughing it up with sandpaper and nothing works.  I’ve had toughies before but this one is really bad.
 
I bought the shell off eBay and it is new old stock in the Cary box unpainted, looking at the info sheet and box I’d estimate it at about 1970.  I’ve stripped it 5 times and have it soaking in vinegar ready to try a sixth time.
 
At this point I’m very open to anything but a hammer, that will happen on #7.
 
 
Mel
 
 
Modeling the early to mid 1950s SP in HO scale since 1951
 
My Model Railroad   
 
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Posted by SouthPenn on Friday, August 14, 2015 3:51 PM
South Penn
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Posted by Ron High on Friday, August 14, 2015 4:08 PM

Are you sure it is a Cary shell. As far as I know the Cary shells were made out of lead . The Hobbytown shells were made out of Zamak.

The lead shells are much heavier tham a zamak shell of the same size.

As far as why paint won't stick I am not sure. I do sometimes see a lot of Hobbytown Zamak shells where paint chips off.The only thing I can suggest is lightly scour off any zamek oxidation with super fine steel wool before your vinegar bath. If it is lead the lead is much softer so be careful.

Ron High

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Posted by RR_Mel on Friday, August 14, 2015 4:14 PM

SouthPenn

Thanks for your input.  The Micro Scale site info on Microprep doesn’t say that it will work on metal so I called Micro Scale and I didn’t get a $16 answer.  I need more than a “Try is and see” answer to spend $16 on a product that “might work”.
 
Have you tried it on Zamak?
 
This is my 7th Cary E7 body and I had some difficulties on one of six earlier bodies but a good cleaning and Automotive primer did the job.  The other five went pretty easy.
 
This is the first time I’ve ever had Zinc Chromate fail on anything.
 
 
Mel
 
 
Modeling the early to mid 1950s SP in HO scale since 1951
 
My Model Railroad   
 
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Posted by RR_Mel on Friday, August 14, 2015 4:43 PM

Ron High

Are you sure it is a Cary shell. As far as I know the Cary shells were made out of lead . The Hobbytown shells were made out of Zamak.

The lead shells are much heavier tham a zamak shell of the same size.

As far as why paint won't stick I am not sure. I do sometimes see a lot of Hobbytown Zamak shells where paint chips off.The only thing I can suggest is lightly scour off any zamek oxidation with super fine steel wool before your vinegar bath. If it is lead the lead is much softer so be careful.

Ron High

 

Thanks for your input Ron. 
 
I do think it’s a Cary shell, it came in a Cary box with a Cary info sheet and it weighs the same as my other Cary E7A bodies.  The reason I said it was Zamak is it isn’t a clear pour like my others were, the texture looks like Zamak.
 
I have two Hobbytown of Boston Shells and like you said they are lighter than a Cary.  The Hobbytown shells also have castings inside tapped for screws and the Cary’s don’t.
 
I tried the steel wool and that polished it and took away what looked like Zamak imperfections but it doesn’t look like pure lead either, pure lead would be pretty soft.  I removed a Cary shell from one of my working units and used the steel wool on the inside of both and they look the same on the inside and weigh the same, both Cary's weigh 13.5 ounces compared to 9.8 ounces for the Hobbytown.
 
 
Mel
 
 
Modeling the early to mid 1950s SP in HO scale since 1951
 
My Model Railroad   
 
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Posted by Ron High on Friday, August 14, 2015 5:24 PM

I just checked the Bowser web site.They picked up the Cary line a few? years back. Their Cary page says they are zinc die cast but the shells are discontinued. All the Cary shells I have on Hobbytwn drives look and feel like lead. I could be wrong. If anyone asked what do I know,I would say for my first 7 years of 44 working for Ma Bell I was a cable splicer. Back then a lot of telephone cables were covered with lead sheath, I spent many a day cutting, sawing ,melting, casting, and soldering lead cables and sleeves .I do know the look and feel of lead ,perhaps Cary or Bowser changed material. Maybe someone on the forum knows. Of course the real issue is what  your paint  stick problem is. I sure don't have an answer again maybe someone has the answer.

Ron High

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Posted by forester6291 on Friday, August 14, 2015 7:52 PM

Home depot sells a test kit for lead paint. Might that do?

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Posted by SouthPenn on Friday, August 14, 2015 8:13 PM

Have you tried something like Rust-oleum primer?

South Penn

South Penn
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Posted by RR_Mel on Friday, August 14, 2015 8:48 PM

SouthPenn

Have you tried something like Rust-oleum primer?

South Penn

 

 

Yes, my first try was Rust-Oleum Primer, second was Rust-Oleum Automotive Primer.  Third try was Rust-Oleum Self Etching Primer.  Fourth was Zinc Chromate, fifth was TCP Primer.
 
A good soaking in Vinegar between forth and fifth.
 
 
 
Mel
 
 
Modeling the early to mid 1950s SP in HO scale since 1951
 
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Posted by zstripe on Friday, August 14, 2015 8:58 PM

Mel,

That shell sounds like the same material, the 50's Ulrich trucks were made out of and is badly oxidized. I had a couple tank trailers still in box from the 50's, (1.95 for kit,by the way) the trailers almost looked liked lead. I used double #00 steel wool with lacquer thinner, the real one, literally soaking it in the thinner and scrubbing with the steel wool, then washing with hot dish detergent water with a toothbrush, blew dry with air-brush and used Floquil reefer white as a primer and used Vallejo scarlet red and Insignia yellow, for the main colors, followed by a coat of Vallejo satin varnish, which is 100% Acrylic resin. The paint all held up great, don't chip, flake.

I believe You said You can't breathe lacquer thinner though....so!!

Carbontetrachloride would have worked beautiful...but they took that off the market for consumer use.

Got rubber gloves? Diluted Muriatic acid would also work.

Good Luck!  Bring it to Me.....We fix em' anything....according to my youngest 35yr.old.

Frank

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Posted by dknelson on Friday, August 14, 2015 10:42 PM

I found an MR Trade Topics review of the Cary E6 body casting and it is described as an antimony lead alloy.  I suspect their other E unit bodies were the same stuff. The Hobbytown E6 was reviewed way back in January 1951.  They describe it as a one piece zamak body casting.  Lead, zamac or zinc alloy - it should take paint regardless -- generations of modelers were able to paint all of those models and materials.  

I wonder if that shell was stored near certain chemicals (or oils, such as cooking oils?) that have permeated it and made the paint unable to stick.  

Years ago I remember reading about the old old MR club layout, the MR&T, back when it was on 1027 N 7th St in Milwaukee.  They found they could not paint a backdrop on the walls because years of printer ink and the solvents used to remove printer ink had permeated the walls and made paint unable to stick.

The diluted muriatic acid idea that Frank mentions might be effective, but that still assumes there is something on the surface of the metal that resists the paint.  

I wonder if an electrical charge method of painting might work too -- I once watched guys repaint old filing cabinets by spraying while an electrical charge was applied to the filing cabinets and the paint flew to the metal like magic.  Of course that was steel and already had (chipped) paint on it.

I have some recollection that some modelers who wanted to solder things onto zamac / zamak bodies of diesels or steam engines -- which ordinarily cannot be soldered -- would have them plated first.  I wonder if your shell could be plated and then painted?  If it is lead that would likely not work.  It should be easy to tell if the shell is lead by trying to scratch into it with a nail (on the inside of course).

Dave Nelson

 

 

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Posted by RR_Mel on Friday, August 14, 2015 10:50 PM

Thanks for the info Frank.
 
I’m not the one with breathing problems, I think that’s Rick.  I’m going to try one more time using the Rust-Oleum Automotive primer in the morning.  I worked it over pretty good this evening with vinegar and the metal ended up with a slightly different look, I don’t see the imperfections in the metal now.
 
I’m going to try baking the primer, tomorrow we go back into the triple digits again with an expected high of 103°.  I’m going to shoot it about 10:30 and set it in direct sunlight for a couple hours.  That has worked for me in the past with difficult paint jobs.  If that doesn’t work I’ll try again Sunday at 107° with a different primer.
 
 
 
Mel
 
 
Modeling the early to mid 1950s SP in HO scale since 1951
 
My Model Railroad   
 
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Posted by RR_Mel on Friday, August 14, 2015 10:57 PM

Thanks Dave
 
If my attempt fails tomorrow I’m going to try Muriatic Acid and cooking it in the Sunday sun at 107°, I came close to trying that a couple of days ago but chickened out.
 
It's getting close to the 3 pound hammer time.
 
 
 
Mel
 
 
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Posted by zstripe on Saturday, August 15, 2015 9:51 AM

Mel,

About 94', I had a close friend got in a accident with His Volvo semi tractor. He knew I did pretty good work, glassing and painting. Body shops wanted 2,000 $$, to repair it. It's an all one piece fiberglass hood/with fenders that swings off of front end to get at engine. Anyway long story short... I had to repair one of the fenders, where headlight is...completely ripped off....luckily He had the ripped off piece and other pieces. I was able to rebuild that whole section and the front where the grill would go, with fine fiberglass mesh and resin. Had it all sanded and primed ready for paint and My compressor took a crap.....so...I went out and bought a case of rattle can rust-oleum pure white enamel paint and put four coats of it on the hood in 100 degree temp. and let it sit all day & night...next day. I wet sanded the whole truck and buffed it out with Imperial Machine Glaze by 3M. when He picked it up that nite, He did not believe that I rattle canned the paint job...It looked that good!!! The Sun makes for a great baking oven.

Didn't mean to ramble, but I believe You are on the right track with Your approach.

Good Luck!!!Big Smile

Frank

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Posted by Ron High on Saturday, August 15, 2015 10:07 AM

Mel keep us up to date with what happens on the paint job.I am sure interested in how it comes out! If you should decide on the 3 pound hammer post a picture!

Ron High

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Posted by Darth Santa Fe on Saturday, August 15, 2015 10:16 AM

I think zamak has a sort of tendency to out-gas if the metal is contaminated? I'm not completely sure though. I have an old American Flyer zamak tender with contamination, and all the old paint is flaking and peeling off. A couple little tiny spots have cracked off too, like contaminated metal does.

What if you went over the whole thing with a fine wire wheel? That might help get surface oxidation out of all the little pits and cracks, which could allow the paint to hold on better?

_________________________________________________________________

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Posted by last mountain & eastern hogger on Saturday, August 15, 2015 10:20 AM

Whistling

Mel if all else fails, I have just been introduced to a product called "STIX". It is a water bourne primer that will even cover ceramic tile or arborite before painting.

My use was for vinyl wrapped base boards that I wanted to paint white.

I just lightly scuffed them up and and wiped them down with a rag dampened with TSP and then primed with STIX and then painted with a latex paint with primer included and it worked great.

Now you would have to experiment a little to see the consistency that would be needed to air brush the product, but this gives you another idea to try.

I found the product at a Benjamin Moore paint Distributor.

Good luck. Johnboy out........................

from Saskatchewan, in the Great White North.. 

We have met the enemy,  and he is us............ (Pogo)

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Posted by RR_Mel on Saturday, August 15, 2015 1:30 PM

 

I want to thank everyone for all the good info and ideas!
 
I have #6 sitting out in the Bakersfield sun cooking.  I gave the shell a vinegar bath for about four hours late yesterday and a good washing then let it sit overnight.  This morning I shot it with Rust-Oleum Self Etching Primer and set it in the sun at 10:20, by 2:00 it should be pushing 100°.  I’m going to let it set overnight and see what happens on Sunday.
 
I’ll let you know what happens Ron, I’m keeping the hammer and camera handy near my workbench.
 
Mel
 
 
Modeling the early to mid 1950s SP in HO scale since 1951
 
My Model Railroad   
 
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Posted by tin can on Saturday, August 15, 2015 10:11 PM

Interesting thread.  Hope try number six works.  I would have thought the vinegar and zinc chromate primer would have worked; that is what I would have tried.  I have a friend who is a custom painter who bakes his paint jobs in a low heat oven (scalecoat paint on brass models) but your weather certainly should suffice.  We had a cool day; 96, first day under 100 this week. 

Remember the tin can; the MKT's central Texas branch...
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Posted by RR_Mel on Sunday, August 16, 2015 8:58 AM

The four hour vinegar soaking and 8 hour cooking at 100° procedure has apparently worked with the primer.  It got cooked pretty good yesterday, I forgot to bring it in so it cooked in the sun for about 8 hours.  This morning the 3M masking tape did not lift the primer.  That’s one in a row!!!!
 
After my masking tape test I shot the primer with the SP Daylight Scheme orange stripe using TCP-107 SP Daylight Orange.  They are predicting 107° today so as soon as my drying spot is in the sun I’ll cook it again.
 
 
I've temporarily hung the 3 pound hammer back on the tool board, wishful thinking.
 
 
 
Mel
 
 
Modeling the early to mid 1950s SP in HO scale since 1951
 
My Model Railroad   
 
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Posted by zstripe on Sunday, August 16, 2015 10:05 AM

Mel,

Yes Yes Yes Yeah

Take Care! Big Smile

Frank

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Posted by ricktrains4824 on Sunday, August 16, 2015 10:34 PM

Mel,

Hope the baking trick works! 

And, yes, you had it right, it's me with the breathing issues.... Asthma.

Glad to know I am so recognized in a model railroad group! Laugh

 

Ricky W.

HO scale Proto-freelancer.

My Railroad rules:

1: It's my railroad, my rules.

2: It's for having fun and enjoyment.

3: Any objections, consult above rules.

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Posted by RR_Mel on Monday, August 17, 2015 4:53 AM

ricktrains4824

Mel,

Hope the baking trick works! 

And, yes, you had it right, it's me with the breathing issues.... Asthma.

Glad to know I am so recognized in a model railroad group! Laugh

 

 

It didn’t get up to 107° yesterday but I let it bake in the old Bako sun for six hours yesterday at 104°.  I’m going to wait until about 9:30 to tape off the orange and shoot the SP Daylight Red.  Then if the tape doesn’t rip of the orange it’s back to the sun again, they say 108° today.
 
 
 
Mel
 
 
Modeling the early to mid 1950s SP in HO scale since 1951
 
My Model Railroad   
 
Bakersfield, California
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Posted by RR_Mel on Monday, August 17, 2015 11:52 AM

Well guys it looks like I finally did it right.  I did a masking tape test this morning and the primer is working like primer should.  The tape didn’t pull up any paint.
 
I went ahead and taped off the orange stripe and shot the Daylight Red then removed the tape.

 
It’s out in what they say will be 108° sun today.
 
The bottom line is I soaked the Zink/Zamak body in vinegar for four hours then let it dry over night and shot it with Rust-Oleum Self Etching Primer.  I set the body on our fence for 8 hours in 100° plus sun then let it cure over night.  I did a masking tape test and the primer was sticking to the body so I shot the Daylight Orange stripe and back out into the 107° sun yesterday for 8 hours.  This morning the orange passed the masking tape test so I taped it and shot the Daylight Red and it’s back in the 107° sun.
 
This was the most frustrating project I’ve done in years.  I want to thank everyone for their input!
 
I hope my experience will help another frustrated model railroader down the track.
 
Glad I didn’t have to use the 3 pound hammer!
 
 
 
Mel
 
 
Modeling the early to mid 1950s SP in HO scale since 1951
 
My Model Railroad   
 
Bakersfield, California
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Posted by ricktrains4824 on Tuesday, August 18, 2015 6:55 PM

Looking good!

Glad to hear the "baking" worked.

Much better looking than the next option..... Whistling

Ricky W.

HO scale Proto-freelancer.

My Railroad rules:

1: It's my railroad, my rules.

2: It's for having fun and enjoyment.

3: Any objections, consult above rules.

  • Member since
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  • From: Bakersfield, CA 93308
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Posted by RR_Mel on Friday, August 21, 2015 4:50 PM

I want to thank everyone for your input and ideas on my troublesome paint job!
 
That little buggar really fought me.  I really don’t know what fixed the problem, the final application of primer was a combination of several things.  Most likely the four hour vinegar bath and the Self Etching Primer helped.  I’m sure the eight hour baking in the 108° Bakersfield Sun helped a lot too.  The bottom line is I didn’t need my three pound hammer and it did turnout looking pretty good.
 
It’s ready for decals.
 
 
 
 
 
Thanks again guys!
 
 
 
Mel
 
 
Modeling the early to mid 1950s SP in HO scale since 1951
 
My Model Railroad   
 
Bakersfield, California
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Posted by Ron High on Friday, August 21, 2015 7:39 PM

Mel I am glad you had sucess.It was great that some of the forum members came up with good suggestions. I will keep them in mind when finishing the rest of my Cary and Hobbytown units.

Ron High

That is a very good looking paint job!

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Posted by RR_Mel on Friday, August 21, 2015 8:08 PM

 

Thanks Ron!
 
For years I used decals on my Daylights and always had problems with them.  One of my HO buddies put me onto an Alps printer and now I make my own decals.  Between my Alps and finding the Scotch masking tapes I haven’t bought a decal in over 5 years.  If I can get the primer to stick I’m in business.  It’s even easier to tape my Daylight stuff and airbrush them than it is to apply decals.  It only took two trys using ¼" 3M Blue Automotive Fineline Masking Tape to get the hang of the Southern Pacific deep V below the headlight.
 
I need to add I also went to Tru-Color Paints, TCP paint goes on better than any paint I’ve ever worked with.
 
Thanks again
 
Mel
 
 
Modeling the early to mid 1950s SP in HO scale since 1951
 
My Model Railroad   
 
Bakersfield, California

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