Primer to avoid

[randyc]

So, thought I'd prime these two right quick.  New can of duplicolor gray primer.  This is NOT kit plastic friendly!  Be warned.  See photos.  

[randyc]

Enlarged photos don't really show the crazing.   I've been spray bombing for years, so it's not like I did some prep thing incorrectly.  Same process as always.   There is just no predicting what new sprays will do with new formulations.  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.  Can't find duplicolors as reliably.  

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.  

[Ace-Garageguy]

 

[crazyjim]

Haven't any issues with Duplicolor sandable primers.

[randyc]

Yes I think I even read that one too.   It's crazy that paints are so wildly inconsistent anymore.   [see what I did there?].  I should have known better and I think that thought fleetingly passed through my mind.   I also realized a few hours later that I was forcing myself to model and impatiently at that.  All mistakes are my own and I know better, but was soo excited to work on these that I made stupid mistakes that I will have to correct on $60 worth of kit plastic.  Mustang and Chevelle.   I want both of these to look very nice. 

Here's an aside - with a 60's era annual or promo, you can do some basic modeling - cleaning parting lines and seams, throw on a Testors enamel spray paint job some interior detailing and you have a reasonably NICE out of box build.   See photo. (59 Imperial photo) But this GT4 and the SS396 deserve better than that.   (Fujimi Daytona & 68 SS396 photo).  Opposite ends of the modeling spectrum.  All of these turned out well and were built at my current house.  (coincidentally, I think all are painted with Rustoleum paints and minimal polishing).   So I know I am capable of a workman like paint job.  I just got impatient and used an unknown and untested paint on what should have been "tested in inconspicuous area for compatibility" as the label might say.  

I had quite a philosophical debate with myself over this.  I used to airbrush a lot.  I would plan out several kits worth of airbrushing, then go to building ("well-ventilated" paint area) and do it all in one session.  I would load the dehydrator as I went and with careful planning could have everything done but the bodies maybe.   And they would be in primer to cure for final sanding/inspection before color, which is a whole other dedicated session.   On the flipside, if I found a part that was missed, I would pop out to building, mix a little paint, spray and be done in a few minutes.  NOW, I can't seem to bring myself to do it that way anymore.  Things happening in life, having to PLAN WHEN I can work on models, WHERE I can work - building?  or house?  With the heat this summer, not a lof of building going on at workbench in outbuilding.   In my former life I had my workbench in the laundry room.  With the new life and wife, I don't get dedicated indoor building space.  Always a set up/takedown thing.   We don't have an extra room to spare for a workbench.  And I really really need to clean my outbuilding work area.   But then I lose a session or two of modeling time.   I say all this because it goes to the heart of WHY I screwed this up.   And what I need to do to get it back to a better place. 

So this is also more than a paint issue for me as a modeler and might need to be it's own post about "did ya ever think about?" kinda thing.   Thanks for reading, y'all...

 

[randyc]

26 minutes ago, crazyjim said:

Haven't any issues with Duplicolor sandable primers.

And maybe that's where I screwed up.  Scratch filling primer this time.  I don't remember when I bought this - not long ago.  Don't remember my thought process, either.  I probably thought this might work better with my current building process of scribing panel lines and such.   HAH!  I just remembered - I bought this to fix my MILs real car.  Then I put the can on my modeling table, figuring I could use it there.  Still my fault for not testing first. 

I've really got to do some organizing....  I did have plans to do that during the first 2 week Covid shutdown back in March, but only got 3 days of one week at home, then I was called back to work - was only person in office for like 3 solid weeks.  and told that I would never be laid off again til the owner or I die.  Or retire.  

[Dave Van]

Duplicolor #1699 sealer for 30 years now. Maybe it was the scratch filler......never even seen that can before. Sorry you had issues.....I used off brand paint on a truck trailer once.....$50 down the drain! 

[oldscool]

i think that a lot of the paint issues that we are having recently have more to do with the plastic than with the paint. Styrene just aint what it used to be.

[Ace-Garageguy]

I've had a lot of semi-disasters using various primers in recent years. The regular Duplicolor crazed one badly, but I was able to save it using PlastiKote "scratch filling" primer...but the formulation was subsequently changed and it's crapp now.

"Scratch-filling" primers are nothing but higher-solids, high-build versions of the regular automotive primers, chemically pretty much the same.

But kit plastic formulation is all over the board these days. You can safely use some hot automotive primers on SOME issues of certain kits, but they'll turn other issues into a wrinkly mess.

I've about given up on automotive primers for most full-body paint work now, especially on recently manufactured kits.

But Tamiya works beautifully and lays out slick and smooth if I shoot it wet like I USED to be able to do with Duplicolor et al.

Yes, it's more expensive, but I'm OK with that as long as it actually works.

[stitchdup]

I've not had any problems with duplicolour primers, but i always use the clear plastic primer for the first couple of coats. The one i have trouble with is simoniz primers, complete waste of money unless you want already dirtied thinners. It looks like it has gone on well, so you leave it a couple of days before topcoating and then the primers cracks under the paint after a couple of weeks

[randyc]

13 minutes ago, Ace-Garageguy said:

I've had a lot of semi-disasters using various primers in recent years. The regular Duplicolor crazed one badly, but I was able to save it using PlastiKote "scratch filling" primer...but the formulation was subsequently changed and it's crapp now.

"Scratch-filling" primers are nothing but higher-solids, high-build versions of the regular automotive primers, chemically pretty much the same.

But kit plastic formulation is all over the board these days. You can safely use some hot automotive primers on SOME issues of certain kits, but they'll turn other issues into a wrinkly mess.

I've about given up on automotive primers for most full-body paint work now, especially on recently manufactured kits.

But Tamiya works beautifully and lays out slick and smooth if I shoot it wet like I USED to be able to do with Duplicolor et al.

Yes, it's more expensive, but I'm OK with that as long as it actually works.

I have a can of the Tamiya primer.   Have to relearn how to spray with it, if I remember correctly.   And it is expensive to a tight wad like me.  Might have to rethink that as well, when a kit costs like they do now.   And I have to plan and order, which fails me often enough - I miss the LHS.  I usually end up stopping by one of the chain auto parts stores and looking through their paints and getting what I *think* will work best.   I also agree that it is likely a PLASTIC issue more than a paint issue these days.  I was surprised that it crazed the Tamiya plastic.   I've got to hit Lowe's this evening for some lacquer thinner.  May peruse the Rustos and see if they have anything usable.   Whites, blacks, such as that.  I really only have these two kits planned at this time, so no needs for anything else.  Works well for interiors too.  If it does craze or not polish up, adds texture.   I used to be big on Krylon for this stuff, but it reacts randomly now as well.

I know some people aren't impressed with HPI GUYs stuff, but I do follow him to see kits and am impressed by the results he gets mostly, working as fast as he does.  He says his builds are usually 2 days.  And the Rustoleum is working for him.  

[Deuces ll]

Question... Is the Rust-Oleum primer self etching like the Duplicolor brand????...

[randyc]

13 minutes ago, stitchdup said:

I've not had any problems with duplicolour primers, but i always use the clear plastic primer for the first couple of coats. The one i have trouble with is simoniz primers, complete waste of money unless you want already dirtied thinners. It looks like it has gone on well, so you leave it a couple of days before topcoating and then the primers cracks under the paint after a couple of weeks

Clear plastic primer?  What's that one?  

[GMP440]

That looks like the primer is crazing.  I've never had that happen with any of the Duplicolor primers.  I've used both the sandable primer and filler primer without any incident.  What was the temp and humidity when you sprayed the body?  My method is to start with the regular primer; if their any pin holes or anything,  fill those and then use the filler primer.  How was the body prepped?  Was it scuffed first before priming?

 

[randyc]

Just now, Deuces ll said:

Question... Is the Rust-Oleum primer self etching like the Duplicolor brand????...

I can't answer that.   Never had any issue with it lifting or flaking on bare or sanded plastic.  But that's my results.  

[Deuces ll]

Thanks Randy....

[randyc]

1 minute ago, GMP440 said:

That looks like the primer is crazing.  I've never had that happen with any of the Duplicolor primers.  I've used both the sandable primer and filler primer without any incident.  What was the temp and humidity when you sprayed the body?  My method is to start with the regular primer; if their any pin holes or anything,  fill those and then use the filler primer.  How was the body prepped?  Was it scuffed first before priming?

 

Mostly scuffed over, but may have been some bare spots.   Warm and pretty humid.   It was borderline on the weather.  I would not have tried to spray a finish coat as it was.  So you 're saying you've had weather affect crazing?  That's new to me or maybe I just missed the connection.   Hmmmm.....   I have had this before, but not regularly enough to connect he weather.   And I realize now that this is a different Duplicolor primer than I usually use.  I hate the sanding trying to fix it, but got no choice.  Ugh.  

[Ace-Garageguy]

Weather has no significant effect on crazing (other than high humidity slightly slowing the flash time, allowing hot solvents to remain longer on the surface). It's simply the hot solvents attacking the plastic substrate.

You CAN mitigate the crazing effect by shooting "mist" coats from farther away (which allows for some solvent evaporation prior to the primer hitting the surface), but this also causes a grainy or orange-peel surface that has to be addressed prior to color. Either way, you're screwed.

Scuffing, however actually CAN have a slightly adverse effect. Injection molded plastic parts have a slightly harder surface...the part that was in direct contact with the hot mold...than the underlying plastic. Scuffing, even the gentle scrubbing with an abrasive cleanser I now favor, can exacerbate the tendency towards solvent crazing...and I know this from experimentation.

So in short...TEST, TEST, and TEST before committing to using ANYTHING on a particular model.

27 minutes ago, randyc said:

... I hate the sanding trying to fix it, but got no choice.  Ugh.  

I feel your pain, but I thought this one was pretty much ruined. In the event, saving it was really pretty easy.

 

Edited August 10, 2020 by Ace-Garageguy

[crazyjim]

Can this Tamiya primer be used under "hot paint like House of Color?

[robertw]

56 minutes ago, Ace-Garageguy said:

I've had a lot of semi-disasters using various primers in recent years. The regular Duplicolor crazed one badly, but I was able to save it using PlastiKote "scratch filling" primer...but the formulation was subsequently changed and it's crapp now.

"Scratch-filling" primers are nothing but higher-solids, high-build versions of the regular automotive primers, chemically pretty much the same.

But kit plastic formulation is all over the board these days. You can safely use some hot automotive primers on SOME issues of certain kits, but they'll turn other issues into a wrinkly mess.

I've about given up on automotive primers for most full-body paint work now, especially on recently manufactured kits.

But Tamiya works beautifully and lays out slick and smooth if I shoot it wet like I USED to be able to do with Duplicolor et al.

Yes, it's more expensive, but I'm OK with that as long as it actually works.

I agree with you ACE. Tamiya Grey or Fine White (I prefer the latter) is what I use exclusively now and I've never had a problem. Yes a little more expensive but knowing that I'll have no problems is worth it.

[Ace-Garageguy]

Just now, crazyjim said:

Can this Tamiya primer be used under "hot paint like House of Color?

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.

[stitchdup]

43 minutes ago, randyc said:

Clear plastic primer?  What's that one?  

Its another duplicolour product. Its meant for bumpers and trim but it seems to work on models too. Since I started using it, masking seems to work better and I've had a lot less crazing 

[stitchdup]

8 minutes ago, crazyjim said:

Can this Tamiya primer be used under "hot paint like House of Color?

No, unless you let it gas out, then use an auto clear to seal it from the hok. I tried it over bare tamiya a couple months ago and the results weren't good, but with the clear it worked nice

[GMP440]

53 minutes ago, randyc said:

Mostly scuffed over, but may have been some bare spots.   Warm and pretty humid.   It was borderline on the weather.  I would not have tried to spray a finish coat as it was.  So you 're saying you've had weather affect crazing?  That's new to me or maybe I just missed the connection.   Hmmmm.....   I have had this before, but not regularly enough to connect he weather.   And I realize now that this is a different Duplicolor primer than I usually use.  I hate the sanding trying to fix it, but got no choice.  Ugh.  

Humidity causes crazing. I don't have this issue because I spray indoors with a spray booth.  Are you spraying outside?  Sometimes it's good to test sprays so that you can see early in the process if you will have any problems.

[Ace-Garageguy]

28 minutes ago, GMP440 said:

Humidity causes crazing.

Nope.

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

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

Edited August 10, 2020 by Ace-Garageguy