Primer to avoid

[GMP440]

  On 8/10/2020 at 4:05 PM, Ace-Garageguy said:

Nope.

Humidity causes "blushing", slow flash-off, slow drying.

I'll stand on my 5+ decades of experience with this stuff.

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Ok.  You mentioned 5+ decades of experience, then share what could be the cause?

[Mark]

The newer rattle-can primers are more cheaply made than before.  Less solids, more thinner.  What they call "filler primer" now used to be sandable primer, today's "sandable primer" is what used to be just plain old primer, and today's "primer" is basically tinted thinner in a spray can.  And, the plastic isn't what it used to be either.  More recycled sprues (the big ones that never made it into the kit box).  Some recycled stuff is actually desirable, it makes the plastic less brittle.  Too much makes it rubbery, which is what we are getting lately.

Whatever you use for primer...shake, shake, shake, particularly the automotive touch-up stuff.  What little solids are in the can need to be shaken into the mix and not left sitting at the bottom of the can when you hit the spray nozzle.

Any newer plastic, I'm spraying the first couple of coats from a distance.  I've had some luck applying one quick blast of the "sealer primer" over whatever other primer is already on.  For me, anyway, this seems to prevent the color coats from potentially raising sanding scratches.

[Ace-Garageguy]

  On 8/10/2020 at 4:37 PM, GMP440 said:

Ok.  You mentioned 5+ decades of experience, then share what could be the cause?

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This thread is full of explaining the actual reason for crazing...solvents in the material being too "hot" for the substrate, and etching into it (this is the same reason that lacquer sprayed over enamel will more than likely cause the enamel to wrinkle, as the hot lacquer solvents leach into the enamel, causing it to swell and detach from the surface).

Also read my previous posts in the thread. I describe more of the mechanisms of the problem, and possible means to mitigate it.

Humidity is nothing but water vapor in the air. Styrene is impervious to water, hence it's not going to craze anything.

A very slim possibility, as I mentioned earlier, is that the slower flash-off you get under high humidity (because the air is already saturated with water vapor, there's nowhere for the solvents to "go" as they want to evaporate out of the material just sprayed) could conceivably cause the surface to stay "wet" longer, allowing more solvent penetration into the plastic substrate...but I've never seen it happen.

EDIT: Folks need to be careful about trusting Rustoleum and Krylon as the fix, too. Rustoleum and Krylon products come in many different flavors, chemically. The special "for plastic" and "fusion" products, for example, have ruined more than one model on the boards over the years.

TEST   TEST   TEST

EDIT 2: decanting Duplicolor primers and airbrushing has a good chance of succeeding where spraying "mist" coats from a rattlecan will more than likely make a grainy surface that will either obliterate detail, or take a lot of careful sanding to prepare for color. An airbrush allows control of the amount of fluid coming out the nozzle in a way rattlecans can't, and a very finely atomized mist from an airbrush can indeed solve crazing.

On doing REAL cars with "sensitive" substrates, I've often been able to achieve high builds of "hot" primers by carefully controlling my air pressure and fluid adjustments...exactly the same idea as airbrushing decanted primers on models.

Edited August 10, 2020 by Ace-Garageguy

[Bugatti Fan]

Primers can be a bit hit and miss unfortunately. Here in the UK there is an Auto Accessory outlet named Halfords, and I have found their own brand primers to be ok. I apply mist coats to start off and allow it to harden and continue gradually with more mist coats and allowing it to harden each time until I have built up to the finish required. This method allows the carrier chemical /thinner to evaporate off more quickly and lessen the chance of eating into the plastic as coats are bulit up gradually. Commercial rattle can primers are developed for automotive and general craft use so can be a bit strong on delicate plastic model parts.

If in any doubt, and do not want your model to disintegrate  like a vampire doused in holy water, then just stick to and use primers that are developed specifically for plastic models like the Tamiya brand

Edited August 10, 2020 by Bugatti Fan

[Snake45]

  On 8/10/2020 at 12:41 PM, randyc said:

Probably going to start sticking with Rustoleum 2x primers and paints.  HPI GUY Chris seems to have good luck and it does seem to work pretty well. 

I did get a can of "Miracal" flat black at Dollar General.  It sprays beautifully.  But in the weather right now, it dries a semi flat dark gray.   Which works for me, as I can mist on other blacks to give different finishes.  

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I haven't had good luck with the Rustoleum 2X stuff. Doesn't cover well and seems "watery" to me. Now I only use it over Walmart cheap primer, and it does okay-ish. 

I just noticed that "Miracal" stuff for the first time the other day. Was tempted, but just laid in a good stock of that Touch N Tone cheap primer. But I like the idea of the "semi flat dark gray." That could be useful. 

[Jordan White]

  On 8/10/2020 at 5:15 PM, Snake45 said:

I haven't had good luck with the Rustoleum 2X stuff. Doesn't cover well and seems "watery" to me. Now I only use it over Walmart cheap primer, and it does okay-ish. 

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I find that the paint can be hit or miss in the coverage department depending on color, but I do find the 2X gray primer to cover very well and gives me minimal issues as well as the 2X aluminum for my silver parts (and as a base for metallics/candy coats).

[randyc]

Wow, thanks for the good information going on here.  Like Ace, I've never had humidity cause a crazing problem.  I have my share of blushing though.   I have also pebbled up a few finishes as well.   With the rate of succes I've had, there are also failures or mishaps.   I try to be consistent and know I hurried this too much.   

I have a sawzall for shaking paint.   Hose clamp the can to the blade and shake till I feel certain it's shook.   I have different size clamps for little botlles, Testor sized cans, and big cans.   I did not properly shake the duplicolor this time.  In a hurry, remember?  So many things I did wrong in a hurry.   Don't know if it would have made a difference.  Doubt it - seen this before.  I still stand behind the product being iffy [at best] for models.   

As for outdoor/indoors, it is in a non climate-controlled building.  out of sun, a fan blowing in the background - not in direction of painting, but still awful warm and humid.  I know there are drying issues out there.   I have had issues with ruddy red primers to the point where I won't use them.  Period.    I save good paint sessions for cooler mornings.   Just wanted to get some primer on to see what else I needed to fix after spending a bit more than an hour cleaning up mold lines and scribing panel lines.  Now I kno w - I need to fix WHOLE CAR>.. ugh... lol

And yes, any paint that says for plastic (fusion) is NOT for a good finish on plastic.   UGH.   Might work on the stuff outside chairs are made of but never had any luck on plastics.  UNLESS I want it to texture, like vinyl seats.  Then you can see where the plastic swirls into the molds.    I really should go back to decanting and airbrushing - that was my best results.  But been trying to use more out of the can finishes for convenience.   See above post about patience.   I know better than to rush.  But I do it anyway and it's showing.   So Ace is probably way right on using the airbrush to improve odds of good finish.  And that may be why i have not had any more issues than I have.  To the point of wondering what builders are doing wrong when they post up.   

THe best primer I ever used was the Duplicolor Hot Rod gray (or was it black?)  At any rate, it was too dark in many cases.  But I could blast that on anyway short of a house paint brush and it would work for me.   

Just going to have to fix these and change some other methodology and maybe products, in future builds.    

 

[charlie8575]

Many body-shop jobbers still carry good-quality sandable grey lacquer primer, formulated with mild solvent, for around $20/quart. I'm seriously thinking of switching to that. Problem is it only comes in grey, nobody seems to make red or white.

I'm also seriously considering saying screw it, and move to all Tamiya primer. I've been able to use it under most paints without trouble.

I wish I could still get Plasti-Kote around here. Nobody seems to carry it.

Charlie Larkin

[gman]

I've had primers from tried & true old cans that used to shoot fine over older plastic formulations etch and cause problems on the newer plastics. That has led me to stick with the more expensive Tamiya primers for when consistency is important, though I recently got some of the Stynylrez primer to try. Initial tests show it lays down smooth and builds nicely- it is just a matter of seeing if it holds up under automotive lacquers and provides a proper barrier coat.

[Ace-Garageguy]

  On 8/10/2020 at 6:53 PM, charlie8575 said:

...I wish I could still get Plasti-Kote around here. Nobody seems to carry it.

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They've reformulated it, and the new stuff is just awful.

[charlie8575]

  On 8/10/2020 at 7:13 PM, Ace-Garageguy said:

They've reformulated it, and the new stuff is just awful.

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That's disappointing. Looks like it'll be the airbrush stuff, Tamiya, or I've considered trying SEM.

Charlie Larkin

[StevenGuthmiller]

  On 8/10/2020 at 3:13 PM, Ace-Garageguy said:

I haven't tried it yet.

I'm about to do some testing under hot Duplicolor rattlecan colors...as soon as I have time.

Steve Guthmiller may know the answer.

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I couldn't tell you.

I've only used Tamiya primer a few times and I didn't see any cost benefit over Duplicolor.

 

I use Duplicolor "sandable" and/or "primer sealer" on every project.

You just need to be aware that it is a hotter primer than any hobby primer, and adjust for that accordingly.

Granted, most of my projects are old kits with more robust plastic than many of the new kits, but I've done some newer kits with the same paint regimen that I use on old ones, and the Duplicolor primers worked fine.

 

My method is to spray a coat of hobby primer, (usually Testors lacquer primer) as my first primer coat.

This helps to seal up the plastic to some extent for the following Duplicolor coats.

It also gives better initial coverage than the Duplicolor primers.

 

The Testors covers well, but it is not as fine or smooth and does not protect as well.

The Duplicolor primers are finer, and go on much thinner and smoother than Testors, especially with the aid of the unmatched "fan spray" nozzles that they have.

 

When I begin with the Duplicolor primer, I start with at least a couple of very light coats, followed by a few more successively heavier ones.

By the time 4 or 5 coats of primer have been applied, I have an extremely smooth base with no sanding between coats.

 

Let's just say that I have had crazing issues with automotive lacquers in the past and my entire painting process has been formulated over many years to avoid it, and with the techniques I use today, with Duplicolor primers, I have zero issues with it.

I'm completely confident going into every paint job that there will be no problems with crazing.

 

In closing, I'll just say that I don't think any paint needs to be "avoided" in conjunction with plastic modeling.

You just need to know how it's going to act before you just leap in and start spraying.

 

Spraying a pretty heavy coat of any hotter automotive primer over bare plastic right off the bat has an even chance of giving you disappointing results.

 

 

 

Steve

 

[Tom Geiger]

I primarily use Duplicolor primers and haven’t had any issues except for Tamiya kits, so I use their primer on those. 

The recent Issues are probably plastic related. The American manufacturers who have product contracted to China are using multiple suppliers and I doubt they have much final control over plastic content. Some Revell products are coming out of Poland too.

I won’t compromise on spray paint for cost. My time, drying time and the quality I  desire are more important than the few dollars I can save.  The Facebook model boards are minefields of guys posting failed paint jobs and asking why. Digging in they’re using some cheap off brand dollar store primer (if primer at all!) and $3 finish paints. I get a chuckle when you try to council them and they argue with you!  My favorite was a guy who said I must be rich, he couldn’t afford Duplicolor! I checked his profile and he owned a new 4x4 crew cab that alternated towing a big boat or pair of Harleys... priorities!

[StevenGuthmiller]

  On 8/11/2020 at 1:39 AM, Tom Geiger said:

I primarily use Duplicolor primers and haven’t had any issues except for Tamiya kits, so I use their primer on those. 

The recent Issues are probably plastic related. The American manufacturers who have product contracted to China are using multiple suppliers and I doubt they have much final control over plastic content. Some Revell products are coming out of Poland too.

I won’t compromise on spray paint for cost. My time, drying time and the quality I  desire are more important than the few dollars I can save.  The Facebook model boards are minefields of guys posting failed paint jobs and asking why. Digging in they’re using some cheap off brand dollar store primer (if primer at all!) and $3 finish paints. I get a chuckle when you try to council them and they argue with you!  My favorite was a guy who said I must be rich, he couldn’t afford Duplicolor! I checked his profile and he owned a new 4x4 crew cab that alternated towing a big boat or pair of Harleys... priorities!

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I agree completely Tom!

The paint is the first thing that will be noticed, and therefore, probably the most important component of building a model car.

Why you would "cheap out" on materials for this step is baffling to me.

Often times, these are the the same people that will spend $3.00 on some discount store finish paint, but have no issues with spending $100.00 on all sorts of after market parts and decals.

 

 

 

 

Steve

[GMP440]

  On 8/10/2020 at 11:42 PM, StevenGuthmiller said:

I couldn't tell you.

I've only used Tamiya primer a few times and I didn't see any cost benefit over Duplicolor.

 

I use Duplicolor "sandable" and/or "primer sealer" on every project.

You just need to be aware that it is a hotter primer than any hobby primer, and adjust for that accordingly.

Granted, most of my projects are old kits with more robust plastic than many of the new kits, but I've done some newer kits with the same paint regimen that I use on old ones, and the Duplicolor primers worked fine.

 

My method is to spray a coat of hobby primer, (usually Testors lacquer primer) as my first primer coat.

This helps to seal up the plastic to some extent for the following Duplicolor coats.

It also gives better initial coverage than the Duplicolor primers.

 

The Testors covers well, but it is not as fine or smooth and does not protect as well.

The Duplicolor primers are finer, and go on much thinner and smoother than Testors, especially with the aid of the unmatched "fan spray" nozzles that they have.

 

When I begin with the Duplicolor primer, I start with at least a couple of very light coats, followed by a few more successively heavier ones.

By the time 4 or 5 coats of primer have been applied, I have an extremely smooth base with no sanding between coats.

 

Let's just say that I have had crazing issues with automotive lacquers in the past and my entire painting process has been formulated over many years to avoid it, and with the techniques I use today, with Duplicolor primers, I have zero issues with it.

I'm completely confident going into every paint job that there will be no problems with crazing.

 

In closing, I'll just say that I don't think any paint needs to be "avoided" in conjunction with plastic modeling.

You just need to know how it's going to act before you just leap in and start spraying.

 

Spraying a pretty heavy coat of any hotter automotive primer over bare plastic right off the bat has an even chance of giving you disappointing results.

 

 

 

Steve

 

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I do the same as you.  I do light coats with duplicolor.  Never a problem.  The same technique I use when doing full scale automotive painting which I have been doing since 85.

[StevenGuthmiller]

  On 8/11/2020 at 4:14 AM, GMP440 said:

I do the same as you.  I do light coats with duplicolor.  Never a problem.  The same technique I use when doing full scale automotive painting which I have been doing since 85.

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As long as you're not heavy handed with the first 2 or 3 coats, you can get by without my suggested use of a first coat of Testors, or other mild primer.

I've done it many times as well.

Where people sometimes get into trouble with a hotter primer like Duplicolor is the misconception that they can spray on one heavy coat and call it good.

The longer that primer sits wet on the surface, at least for the initial coats, the more likely it is to craze the plastic.

 

 

 

 

 

Steve

[Dodge Driver]

For the sake of comparison, here are the formulations of Duplicolor Hot Rod primer and Perfect Match Scratch Filler primer. 

 

 

[BeakDoc]

  On 8/10/2020 at 3:13 PM, Ace-Garageguy said:

I haven't tried it yet.

I'm about to do some testing under hot Duplicolor rattlecan colors...as soon as I have time.

Steve Guthmiller may know the answer.

Expand  

I sprayed Duplicolor Inferno Red over Tamiya pink primer on this “Little Red Wagon” build and was thoroughly impressed with how the two worked together. Prior to going full-bore, I did test it on the stock engine cover from the very same Lindberg kit because I knew I wouldn’t be using it in the build. I try to stay away from mixing manufacturers paint/primer/clear, so this is the only example I can produce as evidence that Tamiya primer and Duplicolor paint can coexist on styrene.

[randyc]

  On 8/11/2020 at 11:12 AM, Dodge Driver said:

For the sake of comparison, here are the formulations of Duplicolor Hot Rod primer and Perfect Match Scratch Filler primer. 

 

 

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I see enough differences to make me at least wonder.   Thanks for the information.

[randyc]

  On 8/11/2020 at 1:39 AM, Tom Geiger said:

I primarily use Duplicolor primers and haven’t had any issues except for Tamiya kits, so I use their primer on those. 

The recent Issues are probably plastic related. The American manufacturers who have product contracted to China are using multiple suppliers and I doubt they have much final control over plastic content. Some Revell products are coming out of Poland too.

I won’t compromise on spray paint for cost. My time, drying time and the quality I  desire are more important than the few dollars I can save.  The Facebook model boards are minefields of guys posting failed paint jobs and asking why. Digging in they’re using some cheap off brand dollar store primer (if primer at all!) and $3 finish paints. I get a chuckle when you try to council them and they argue with you!  My favorite was a guy who said I must be rich, he couldn’t afford Duplicolor! I checked his profile and he owned a new 4x4 crew cab that alternated towing a big boat or pair of Harleys... priorities!

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I'm a cheapskate modeler to the degree that some things I just can't justify.  I can get a pretty dang nice finish with those Testors $3 cans for my final finish  I don't mind spending on a quality product.  I prefer Duplicolor primers becasue they have worked in the past, local availability, and cost.   I have not learned to ORDER modeling supplies yet.  My fault.   THe FB model boards are full of folks with weird issues.  

[Ace-Garageguy]

  On 8/11/2020 at 11:12 AM, Dodge Driver said:

For the sake of comparison, here are the formulations of Duplicolor Hot Rod primer and Perfect Match Scratch Filler primer. 

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Good info.

And one BIG takeaway is the fact that both products can be anywhere from 25% to 50% acetone.

Acetone is a hot solvent, and can be used on its own as plastic cement...because it melts styrene.

No surprise it causes crazing on some model parts if a heavy coat is applied.

The second product can also be between 10% to 24% methyl ethyl ketone...STRAIGHT PLASTIC CEMENT.

EDIT: Note that the allowable variations in percentage of solvents can easily account for variations in coverage as well as crazing from batch to batch. Obviously, a can that's 50% acetone is going to cover worse and craze more than a can that's only 25% acetone.

Edited August 11, 2020 by Ace-Garageguy

[Ace-Garageguy]

  On 8/11/2020 at 12:20 PM, BeakDoc said:

I sprayed Duplicolor Inferno Red over Tamiya pink primer on this “Little Red Wagon” build and was thoroughly impressed with how the two worked together. Prior to going full-bore, I did test it on the stock engine cover from the very same Lindberg kit because I knew I wouldn’t be using it in the build. I try to stay away from mixing manufacturers paint/primer/clear, so this is the only example I can produce as evidence that Tamiya primer and Duplicolor paint can coexist on styrene.

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Nice example, good info. Thanks.

Like you, I'm wary of mixing materials from different manufacturers. I've seen countless cowboys in real-car paint shops having all kinds of issues...and mindlessly wondering why...simply because they assumed everything would work with everything else.

Wrong.

[randyc]

  On 8/10/2020 at 11:42 PM, StevenGuthmiller said:

I couldn't tell you.

I've only used Tamiya primer a few times and I didn't see any cost benefit over Duplicolor.

 

I use Duplicolor "sandable" and/or "primer sealer" on every project.

You just need to be aware that it is a hotter primer than any hobby primer, and adjust for that accordingly.

Granted, most of my projects are old kits with more robust plastic than many of the new kits, but I've done some newer kits with the same paint regimen that I use on old ones, and the Duplicolor primers worked fine.

 

My method is to spray a coat of hobby primer, (usually Testors lacquer primer) as my first primer coat.

This helps to seal up the plastic to some extent for the following Duplicolor coats.

It also gives better initial coverage than the Duplicolor primers.

 

The Testors covers well, but it is not as fine or smooth and does not protect as well.

The Duplicolor primers are finer, and go on much thinner and smoother than Testors, especially with the aid of the unmatched "fan spray" nozzles that they have.

 

When I begin with the Duplicolor primer, I start with at least a couple of very light coats, followed by a few more successively heavier ones.

By the time 4 or 5 coats of primer have been applied, I have an extremely smooth base with no sanding between coats.

 

Let's just say that I have had crazing issues with automotive lacquers in the past and my entire painting process has been formulated over many years to avoid it, and with the techniques I use today, with Duplicolor primers, I have zero issues with it.

I'm completely confident going into every paint job that there will be no problems with crazing.

 

In closing, I'll just say that I don't think any paint needs to be "avoided" in conjunction with plastic modeling.

You just need to know how it's going to act before you just leap in and start spraying.

 

Spraying a pretty heavy coat of any hotter automotive primer over bare plastic right off the bat has an even chance of giving you disappointing results.

 

 

 

Steve

 

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Good post, good points.   I don't ever intentionally put on a heavy first coat.   And as soon as I saw what was happening, I stopped.   Like you I have had a systematic approach and think that I inadvertently used the wrong product from what I am used to.  THis is NOT my normal primer, but I wasn't thinking at the time.  LESSON LEARNED.  

This primer might have worked had I realized it was different and I had taken a different approach to it.  I'm glad you guys are contributing to this discussion so everyone can improve from the mistakes of others.   

When I run out of my existing primer, I will definitely be coming back here to help make my next decision.   I noticed at Lowes last night that they don't have the 2x Rusto.  They do have a few duplicolor branded primers.   I guess WalMart is the place for 2x?   I haven't been there since before the Covid thing and don't want to go to the local one because people in our area are idiots and don't think the virus is real; therefore they don't wear masks, social distance etc.   Gives me the heebie jeebies.  Lowes is only better due to reduced volume of customers.  

[randyc]

  On 8/11/2020 at 1:08 PM, Ace-Garageguy said:

Good info.

And one BIG takeaway is the fact that both products can be anywhere from 25% to 50% acetone.

Acetone is a hot solvent, and can be used on its own as plastic cement...because it melts styrene.

No surprise it causes crazing on some model parts if a heavy coat is applied.

The second product can also be between 10% to 24% methyl ethyl ketone...STRAIGHT PLASTIC CEMENT.

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The MEK is what I noticed as well.   I work in sign industry and MEK is what we use to glue trim to plastic sign faces.  I know how stout that stuff is.  The difference in volume in those two may explain the issue.  I will not use that primer on plastic that is to be shiny again.  As I have said so many times in this thread...LESSON LEARNED.    That stuff worked pretty well in repairing a spot on mother-in-law's car.  That's what is was bought for and I had forgotten that when I used it.   It wasn't my normal primer.  

[slusher]

  On 8/11/2020 at 12:20 PM, BeakDoc said:

I sprayed Duplicolor Inferno Red over Tamiya pink primer on this “Little Red Wagon” build and was thoroughly impressed with how the two worked together. Prior to going full-bore, I did test it on the stock engine cover from the very same Lindberg kit because I knew I wouldn’t be using it in the build. I try to stay away from mixing manufacturers paint/primer/clear, so this is the only example I can produce as evidence that Tamiya primer and Duplicolor paint can coexist on styrene.

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I have used Duplicolor over Tamiya primer.  When finding my favorite primer began to be a pain I went with Tamiya primer and love it. Walmart has a great primer but it’s not stocked often and I am not mail ordering and stocking paint and primer..