Dupli-color primers

[Tom Geiger]

  On 12/19/2020 at 12:03 AM, AMT68 said:

Not sure I would enter the event but learning to build more systematically would provide a benefit overall. 

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You can watch!  There’s a lot of spectators who comment on the progress posts and cheer people on!

[NOBLNG]

I’ve never sanded an entire body before primer. I do however scrub them with a toothbrush and comet which scuffs it lightly. Then I follow up with dawn dish soap and water.

 

[StevenGuthmiller]

  On 12/18/2020 at 9:22 PM, AMT68 said:

 

No I most likely didn't but then I normally don't sand bodies (just scribe and sand out inconsistencies in the plastic) and yet there isn't this problem with hobby paints. So that's why I thought there was a problem with the hobby primer under an auto lacquer. 

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It is definitely an adhesion problem, but I would question whether it has much to do with sanding the body first.

I very rarely sand the entire body of a model, and never have this sort of issue.

This appears to me to be an adhesion problem between the plastic and primer and has nothing to do with the paint itself.

If you want to continue to use the same painting regimen, sanding might help to contain it, but a good primer should not flake off with a finger nail under any circumstance.

This is where the idea of a mildly "hot" primer might actually be beneficial.

It will etch into the plastic to some degree instead of just floating on top.

 

 

 

Steve

[peteski]

  On 12/18/2020 at 9:14 PM, AMT68 said:

Thanks Roger for the reply. I actually do have a picture of a model I painted last summer. I can literally keep scraping it right down to the bare plastic with a fingernail.

 

 

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You mentioned Summer, and you are in New Jersey. Is is possible that you painted on a humid day, and some moisture got trapped under or in the primer, messing up its adhesion to the model's body?

[Erik Smith]

  On 12/18/2020 at 9:14 PM, AMT68 said:

Thanks Roger for the reply. I actually do have a picture of a model I painted last summer. I can literally keep scraping it right down to the bare plastic with a fingernail.

 

 

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I quit using the “sealer” because it had issues peeling off of plastic. Tamiya tape would pull it off. 
I have never had issues with the “filler” peeling, but it is too hot for many new plastic kits. 
I just use Tamiya now. 

[AMT68]

  On 12/19/2020 at 2:02 AM, StevenGuthmiller said:

This is where the idea of a mildly "hot" primer might actually be beneficial.

It will etch into the plastic to some degree instead of just floating on top

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I see your logic with using a primer that would moderately etch the plastic thus creating better adhesion. So some experimentation with primers along with lightly sanding the body prior to priming in order to see what works best. 

[AMT68]

  On 12/19/2020 at 2:27 AM, peteski said:

  On 12/18/2020 at 9:14 PM, AMT68 said:

 

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You mentioned Summer, and you are in New Jersey. Is is possible that you painted on a humid day, and some moisture got trapped under or in the primer, messing up its adhesion to the model's body?

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It's interesting you mention that Peter because while I do make every attempt to be aware of the ambient conditions it's possible this was done under less than ideal conditions. But this same situation occurred with another model I painted with Dupli-color after the summer. 

[AMT68]

  On 12/19/2020 at 2:32 AM, Erik Smith said:

I quit using the “sealer” because it had issues peeling off of plastic. Tamiya tape would pull it off. 
I have never had issues with the “filler” peeling, but it is too hot for many new plastic kits. 
I just use Tamiya now. 

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Well I'm glad you mentioned that Eric. I know not to consider the "filler" I'm surprised to hear Tamiya tape would lift the paint since it's pretty low adhesion. I've had  problems with Testors model tape lifting off paint. 

[Bills72sj]

  On 12/19/2020 at 2:02 AM, StevenGuthmiller said:

It is definitely an adhesion problem, but I would question whether it has much to do with sanding the body first.

I very rarely sand the entire body of a model, and never have this sort of issue.

This appears to me to be an adhesion problem between the plastic and primer and has nothing to do with the paint itself.

If you want to continue to use the same painting regimen, sanding might help to contain it, but a good primer should not flake off with a finger nail under any circumstance.

This is where the idea of a mildly "hot" primer might actually be beneficial.

It will etch into the plastic to some degree instead of just floating on top.

Steve

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I am in agreement with Steve. Whatever solvents are in the primer or paint are the key to adhesion. An oil (and debris) free surface is of benefit too. Sanding can give some paints some "tooth" to hang onto. Especially water based paints. I have recently modified my body prep by washing the body with dish soap and a green Scotchbrite pad or sponge. Finger oils are removed but body plastic is not.

[Plowboy]

The thing about using mildly hot lacquer primers is it may etch into one body and craze another. Someone started a thread not too long ago about one of the Dupli Color primers (think it was RandyC?) and it crazed certain areas on a '68 Chevelle. To me, it just makes more sense to use a primer that's formulated to use over styrene. I used to use Dupli Color primer. Until I started having issues with it. 

[Straightliner59]

If you want to skip the sanding, simply wash the body using Soft Scrub cleanser and an old toothbrush. The Soft Scrub is mildly abrasive and helps give the primer some "bite". I learned it from Don Fahrni, and anything that was good enough for him, is good enough for anyone!

[StevenGuthmiller]

  On 12/19/2020 at 4:29 AM, Plowboy said:

The thing about using mildly hot lacquer primers is it may etch into one body and craze another. Someone started a thread not too long ago about one of the Dupli Color primers (think it was RandyC?) and it crazed certain areas on a '68 Chevelle. To me, it just makes more sense to use a primer that's formulated to use over styrene. I used to use Dupli Color primer. Until I started having issues with it. 

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I agree that it might be a tight rope to walk in some circumstances.

I will disclose, and I'm sure that some of you know, that I build mostly vintage kits.

Apparently the plastic is more stable.

But I have used the exact same method described on new kits with equal results.

 

A single coat of a hobby primer, (I use Testors because it's readily available) gives coverage and a slight barrier to the hotter Duplicolor primer to follow.

The subsequent coats of Duplicolor will still make it's way through the Testors to the plastic and help with adhesion, but the trick is to monitor the heaviness of the coats.

Very light coats to begin, with heavier coats in the end.

 

Anyway, I will call this a theory, but it has come with many years of experimentation and it never fails me.

 

My 3 main issues with using Tamiya primers are of course cost, the fact that I really don't like the nozzles, and the fact that it's never been readily available to me locally, and I refuse to order paint in spray cans on line.

If I need primer, I can pop down to my local auto parts store and pick up all of the Duplicolor that I need.

No messing with ordering, shipping and waiting for product to arrive.

 

I guess that you could say that I prefer to keep something like primer low on my list of priorities to worry about since I have arrived at a virtually fool proof system for using the Duplicolor.

 

 

 

Steve

Edited December 19, 2020 by StevenGuthmiller

[AMT68]

  On 12/19/2020 at 4:29 AM, Plowboy said:

The thing about using mildly hot lacquer primers is it may etch into one body and craze another. Someone started a thread not too long ago about one of the Dupli Color primers (think it was RandyC?) and it crazed certain areas on a '68 Chevelle. To me, it just makes more sense to use a primer that's formulated to use over styrene. I used to use Dupli Color primer. Until I started having issues with it. 

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That's a good point. I have good number of the early '80's Monogram kits and would be less inclined to use auto primers on them. I've found the plastics used in those kits to be much more sensitive as I have to use glue very sparingly on those models. 

[AMT68]

  On 12/19/2020 at 6:47 AM, Straightliner59 said:

If you want to skip the sanding, simply wash the body using Soft Scrub cleanser and an old toothbrush. The Soft Scrub is mildly abrasive and helps give the primer some "bite". I learned it from Don Fahrni, and anything that was good enough for him, is good enough for anyone!

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Never thought about Soft Scrub. Possibly a green Scotch Brite like Bill mentioned would also help to scuff the surface without sanding off any detail or misshaping the panel lines. 

[AMT68]

  On 12/19/2020 at 7:42 AM, StevenGuthmiller said:

The subsequent coats of Duplicolor will still make it's way through the Testors to the plastic and help with adhesion, but the trick is to monitor the heaviness of the coats.

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Glad you mentioned that as I didn't realize the Dupli-color would melt through the Testors primer even with using mist coats initially followed by successive heavier coats. 

Edited December 19, 2020 by AMT68

[Plowboy]

  On 12/19/2020 at 11:40 AM, AMT68 said:

That's a good point. I have good number of the early '80's Monogram kits and would be less inclined to use auto primers on them. I've found the plastics used in those kits to be much more sensitive as I have to use glue very sparingly on those models. 

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Don't forget the '90s stuff either Tom. Especially AMT kits. Some of those are pretty soft. As long as you get the body scuffed with whichever method you choose, you won't have any more problems. I usually go over the entire body with 400, shoot a very light coat of primer and sand again with 600. Any issues I may have missed will show. If all is good, I shoot the final primer.

[StevenGuthmiller]

  On 12/19/2020 at 11:46 AM, AMT68 said:

Glad you mentioned that as I didn't realize the Dupli-color would melt through the Testors primer even with using mist coats initially followed by successive heavier coats. 

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I won't pretend to know all of the science behind it, because I don't.

All that I can tell you is that it works.

If you follow the method that I presented, you won't have any issues with chipping or crazing using Duplicolor products, and it shouldn't make any difference what type, or how old the plastic is.

 

 

Just one of a million different suggestions that you might get on this subject.

It's your decision to make.

 

 

 

 

Steve

Edited December 19, 2020 by StevenGuthmiller

[AMT68]

Well I appreciate all of your responses and the insight provided on the subject. I have enough information to most likely achieve greater success using Dupli-color top coats. While I like the hobby color coats like Tamiya the auto lacquers provide the increased variety that I seek. I enjoyed the robust discussion and it's why I signed up here in the first place. 

[cobraman]

Late perhaps but chalk me up as another who uses only Duplicolor. Gray and while depending on color coats.

[AMT68]

  On 12/20/2020 at 1:03 AM, cobraman said:

Late perhaps but chalk me up as another who uses only Duplicolor. Gray and while depending on color coats.

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Just out of curiosity which color top coats do you use over a white primer?  I ask because with all of the models I've done the last couple of years since I got back into the hobby for the first time in decades I've only used gray primer. 

Edited December 20, 2020 by AMT68

[Straightliner59]

  On 12/20/2020 at 1:17 AM, AMT68 said:

Just out of curiosity which color top coats do you use over a white primer?  I ask because with all of the models I've done the last couple of years since I got back into the hobby for the first time in decades I've only used gray primer. 

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Oh, boy! That's a whole new can of worms! By changing the color of primer, top coats can be altered  in warmth and depth of color. Same thing for using gold or silver undercoats. Many builders use plastic spoons to test these different effects on colors. I hope that made sense. If not, someone soon will help you make sense of it! ?

[StevenGuthmiller]

  On 12/20/2020 at 1:17 AM, AMT68 said:

Just out of curiosity which color top coats do you use over a white primer?  I ask because with all of the models I've done the last couple of years since I got back into the hobby for the first time in decades I've only used gray primer. 

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I use white primer pretty much only when I'm using a very light finish color.

As Daniel stated, primer color can affect the final color to some degree if the finish paint color you are using has some transparency, but as a rule, paints like Duplicolor Perfect Match touch up paints are very opaque, especially if you are using several coats, and the primer color has little affect on the final finish.

I use white primer primarily because it's much easier to get good coverage with a color such as white over white primer, rather than over gray or red.

 

 

 

 

Steve

Edited December 20, 2020 by StevenGuthmiller

[AMT68]

  On 12/20/2020 at 1:40 AM, Straightliner59 said:

Oh, boy! That's a whole new can of worms! By changing the color of primer, top coats can be altered  in warmth and depth of color. Same thing for using gold or silver undercoats. Many builders use plastic spoons to test these different effects on colors. I hope that made sense. If not, someone soon will help you make sense of it! ?

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Thanks Daniel. That makes sense that the primer would affect the final color and to your point some experimentation before hand would be in order. 

[AMT68]

  On 12/20/2020 at 3:20 AM, StevenGuthmiller said:

I use white primer pretty much only when I'm using a very light finish color.

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Thanks for that tip Steve. To this point I've only used gray under lighter colors so I will definitely grab a can of white primer. As far as certain paints being unaffected by the primer coat I remember your WIP on the '64 Grand Prix (while on the SA forum) and how the Sunfire Red wasn't impacted by the dark red basecoat. 

[StevenGuthmiller]

  On 12/20/2020 at 3:39 AM, AMT68 said:

Thanks for that tip Steve. To this point I've only used gray under lighter colors so I will definitely grab a can of white primer. As far as certain paints being unaffected by the primer coat I remember your WIP on the '64 Grand Prix (while on the SA forum) and how the Sunfire Red wasn't impacted by the dark red basecoat. 

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Exactly.

 

 

 

Steve