My primer smells like Bondo.....

[JollySipper]

Hey, Guys...... I'm just curious about this. Why would the primer I'm using smell like Bondo? It is intended for metal. I don't think I've ever used a primer with this odor.....

It's a really good product, if a little thin.

[1972coronet]

Is it Red Oxide ? Scratch-Fill ? Those are, in es., "spot putty" that's been thinned for spraying. 

I don't know enough about which was "first" : putty or primer. I've seen spot putty thinned with lacquer thinner then sprayed, but I don't know of the chemistry behind it beyond what I've seen a handful of times.

[JollySipper]

26 minutes ago, 1972coronet said:

Is it Red Oxide ? Scratch-Fill ?

It's neither of those..... It's just flat gray. Maybe it shares some chemical with Bondo that helps it bond to the substrate?

Edited May 5, 2023 by JollySipper

[peteski]

If you are talking about the 2-part Bondo then I believe the smell is liquid polyester resin.

[ctruss53]

Not sure why it smells like that. But it says in at least two places that scale models are not the intended use for that stuff.

Edited May 5, 2023 by ctruss53

[JollySipper]

6 minutes ago, ctruss53 said:

Not sure why it smells like that. But it says in at least two places that scale models are not the intended use for that stuff.

It works so well on them, though! I just primed this today with it........

No crazing, it's super smooth and dries fast......

[Dave G.]

The Krylon Platinum gray used to be a great model primer I thought. It has or had a thinner film than some of the other colors. But that was 30 years ago, who know about todays formulation. I can't even find Krylon around this area where I live these days. And at Micheals where short cuts are supposed to be stocked most of the slots are empty.

[SfanGoch]

Ace Hardware. Lowe's and Home Depot carry Krylon. So do Sherwin-Williams paint stores, since S-W owns Krylon.

[Ace-Garageguy]

You have aroused my curiosity, so I'll be trying some myself.

The primary stink from polyester resin (the liquid part of "bondo") is styrene monomer, and there are regulations regarding its atmospheric release under industrial conditions.

Styrene-monomer is a major component of polyester resin, and can be used as a thinner for polyester-resin-based products, like bondo, in small quantities.

I see the product above is marked as "direct to metal" (DTM).

DTM rattlecan primers are fairly newish in the consumer market, and they do smell different, though I haven't ever looked into the chemical makeup (we use them frequently under spot repairs and on small fabrication jobs in the body shop).

I'll be investigating further...

Edited May 6, 2023 by Ace-Garageguy

[Mark]

If it's "direct to metal", wonder how it would work for repainting a die-cast as opposed to starting with etching primer?

 

 

 

 

 

[Ace-Garageguy]

52 minutes ago, Mark said:

If it's "direct to metal", wonder how it would work for repainting a die-cast as opposed to starting with etching primer?

Probably be fine, possibly easier.

It's permissible to put fillers over the "professional" bodyshop rattlecan DTM primers (at least that's the current understanding from the paint reps here).

EDIT: Scuffing the surface with 180 grit is recommended before filler is applied if the DTM primer is fully dry.

EDIT 2: DTM rattlecan primers are very helpful in a bodyshop, as small areas of "open" metal work (bare steel) can be easily protected from flash rusting using the rattlecan product, as opposed to having to mix and spray a two-part product like PPG's DP epoxy, which takes additional time and can raise material cost and the potential for waste significantly.

Edited May 6, 2023 by Ace-Garageguy

[stitchdup]

1 hour ago, Ace-Garageguy said:

Probably be fine, possibly easier.

It's permissible to put fillers over the "professional" bodyshop rattlecan DTM primers (at least that's the current understanding from the paint reps here).

EDIT: Scuffing the surface with 180 grit is recommended before filler is applied if the DTM primer is fully dry.

EDIT 2: DTM rattlecan primers are very helpful in a bodyshop, as small areas of "open" metal work (bare steel) can be easily protected from flash rusting using the rattlecan product, as opposed to having to mix and spray a two-part product like PPG's DP epoxy, which takes additional time and can raise material cost and the potential for waste significantly.

I'd always guessed the dtm meant it was a weld through primer. I'm sure they used similar cans for this on texas metal when they did the caddilac drop top

[Ace-Garageguy]

7 minutes ago, stitchdup said:

I'd always guessed the dtm meant it was a weld through primer. I'm sure they used similar cans for this on texas metal when they did the caddilac drop top

To the best of my current knowledge, "weld-through primer" and "direct-to-metal primer" are different products for different specific applications.

Note I said "to the best of my current knowledge".

I'll be looking into it.

[SfanGoch]

What I found:

What Does Direct-To-Metal Mean?

What Does Weld Through Primer Mean?

[JollySipper]

4 hours ago, Ace-Garageguy said:

I'll be looking into it.

Whatever you do find out, it does make a good primer...... I was able to wet sand it the same day that I sprayed it.

[peteski]

Looking at the info in Joe's links "direct to metal" primer makes no sense as the explanation is that the direct-to-metal finishes can be applied directly to bare metal, without a need for a primer. So how can a primer be rated directly-to-metal?  Aren't most rattle can automotive primers made to be applied directly to metal?  I guess self-etching primer is just another marketing term (as this primer, along with others, can be applied directly to bare metal). Are we thoroughly confused yet?

[SfanGoch]

Ask three people what time it is and you'll get three different answers. Those links contained the least confusing descriptions of either type found on Google.

[Ace-Garageguy]

18 hours ago, peteski said:

...So how can a primer be rated directly-to-metal? 

...Are we thoroughly confused yet?

Just FYI, in the REAL car world, there are primers that are NOT recommended for application "direct to metal", like most urethane primer-surfacers (recommended to be applied over epoxy primers or self-etching primers).

But it gets "confusing" real quick, as it's usually recommended you don't put polyester high-build primer-surfacers over self-etch (except for Featherfill G2, and that doesn't always work right). However, polyester high-build primers and other polyester products (like bondo) work well over epoxy primers.

And this is why, in the real-car world, smart guys stay within one product brand to avoid unpleasant surprises, as manufacturers test all their own stuff for compatibility and give you instructions as to what works with what.

But I've known plenty of cowboys in the bodyshop biz who think they're smarter than the chemists at DuPont or PPG, and mix anything that's cheap with anything else that's cheap...just like a lot of modelers. And God forbid they'd ever actually read the product TDS or application instructions.

And you know what? They have the same kinds of problems modelers have from trying to save a few bucks. But a redo on a real car can cost many hundreds of $$$ in material alone. Pretty clever way to save money, right?

Bottom line if you want repeatable GOOD paint jobs on your models: stay with products made for modeling, or products that have been tested extensively and recently (like Duplicolor primers)...OR...do your own extensive testing yourself before you start combining stuff because some random guy on the internet said it worked.

EDIT: In a lot of cases, the labeling of consumer-oriented refinishing materials has very little to do with reality, and is simply rebleating words some marketing guy who knows little about anything and cares less came across somewhere.

For instance, I've seen "2K" rattlecan products that aren't anything remotely resembling true two-part catalyzed products.

Paint manufacturers for real cars pretty much HAVE to get their labeling and product usage info right, or they won't be in business for long.

But some company turning out second and third rate paint that's going to get shot full of runs and dribbles and dirt on granny's lawn chairs doesn't generally hold itself to the same standards.

 

 

Edited May 9, 2023 by Ace-Garageguy
TYPO

[bobthehobbyguy]

1 hour ago, Ace-Garageguy said:

And this is why, in the real-car world, smart guys stay within one product brand to avoid unpleasant surprises, as manufacturers test all their own stuff for compatibility and give you instructions as to what works with what.

Exactly. And just because mixing and matching might work once or twice that's no guarantee that is going to work every time.

[Mark]

Not singling anyone out here, but after so many years it still blows my mind that people will just grab the easiest to reach spray cans and start blasting a never-before-tried paint combination on something they have just put a BLAH_BLAH_BLAH_BLAH-ton of hours into...

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Rick L]

On 5/6/2023 at 10:42 AM, Ace-Garageguy said:

Probably be fine, possibly easier.

It's permissible to put fillers over the "professional" bodyshop rattlecan DTM primers (at least that's the current understanding from the paint reps here).

EDIT: Scuffing the surface with 180 grit is recommended before filler is applied if the DTM primer is fully dry.

EDIT 2: DTM rattlecan primers are very helpful in a bodyshop, as small areas of "open" metal work (bare steel) can be easily protected from flash rusting using the rattlecan product, as opposed to having to mix and spray a two-part product like PPG's DP epoxy, which takes additional time and can raise material cost and the potential for waste significantly.

I don’t doubt 180 grit is recommended for 1:1 harsh environment but do you really think it applies to scale models?

[SfanGoch]

Bill was referring to working in an auto shop environment.

[Ace-Garageguy]

2 hours ago, Rick L said:

I don’t doubt 180 grit is recommended for 1:1 harsh environment but do you really think it applies to scale models?

The question was about using DTM primers on die-cast, I related the answer to real-car practice, and yes, I'd definitely scuff fully dry DTM primer with 180 prior to applying polyester filler. 

I usually scuff plastic with 180 prior to applying polyester filler as well.

And I don't have adhesion or featheredge lifting problems. Ever.

EDIT: I have had featheredge lifting problems after applying polyester (catalyzed 2-part) over plastic only scuffed with 400 or so. After shaping and featheredging, subsequent priming with lacquer primer would sometimes pull up the featheredge.

But hey...I've been experimenting for decades, and I know what works for me. 

Edited May 9, 2023 by Ace-Garageguy

[bobthehobbyguy]

15 hours ago, Mark said:

Not singling anyone out here, but after so many years it still blows my mind that people will just grab the easiest to reach spray cans and start blasting a never-before-tried paint combination on something they have just put a BLAH_BLAH_BLAH_BLAH-ton of hours into...

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Even if it's not a project with a lot of work an out of the box project can come to a screeching halt with a bad combination of paints. Definitely a way to get frustrated and have to strip a project.