Primer for small metal parts

[aymodeler]

I am progressing to the point on my Artesania Latina Virginia build to where I need to start thinking about painting some of the smaller metal parts.

 

Any advise on a good primer to use on such small parts? I will be using acrylic paints. I am thinking of just good old Binz primer as I have plenty of this around and it has always served me well (albeit in MUCH larger applications 😀).

[Roger Pellett]

I’m assuming that you’re referring to the typical cast metal parts supplied with kits.  If so, I have been recently been painting cast metal soldiers.  The ones that I like were made by a company now out of business so I buy them on EBay and have no control over their date of manufacture.  This means that some are lead alloy white metal and some lead free pewter.

 

I have had good results with Tamiya white primer.  It is usually available  at our local Hobby Lobby and also on Amazon.  It comes in a spray can, and covers with light coats that don’t hide detail.  It is compatible with acrylic model paints.

 

Roger

Edited February 14, 2021 by Roger Pellett

[aymodeler]

Thanks Roger. Yes, I am referring to the typical "white metal" castings. I'll give the Tamiya spray primer a try.

[Snug Harbor Johnny]

Zinc based alloys (sometimes called 'pot metal') can be first painted with zinc chromate wash primer before applying a regular metal primer.  Die cast (1950s and earlier) model locomotive (Lionel, Marx, etc.) were of zinc.  Lead or (currently) tin based alloys are soft and easily bendable - a 'scratch test' in an inconspicuous place can be an indicator.  Zinc alloys are 'tougher' and less bendy, with a higher melting point than the former types.

[wefalck]

I find that small parts that are not fingered don't actually need to be primed, that is, when you apply the paint with an airbrush. Just keep coats sparse.

[bridgman]

Any experience on using dewaxed shellac as a brush on primer for small metal parts? Universally available

and supposedly compatible with many finishes.

Thanks

Bridgman Bob

[Landlubber Mike]

I used this on 1/700 brass photo etch and it worked really well.  Smells terrible, but the paint held on very nicely with great coverage (Vallejo).  The Mr. Hobby stuff is a little pricier, but I've really enjoyed working with their primers like Mr. Surfacer and Mr. Finisher.  

 

 

 

 

 

Edited February 15, 2021 by Landlubber Mike

[wefalck]

Some (non-model) companies also sell acrylic emulsions without pigment as primers, but I have not been happy with the resulting surface.

 

Shellac would work, but one may still see streaks from brushing it on - due to the short drying time, spraying may be difficut and it requires good ventilation, as pure alcohol is used as medium.

[Bob Cleek]

44 minutes ago, wefalck said:

Shellac would work, but one may still see streaks from brushing it on - due to the short drying time, spraying may be difficut and it requires good ventilation, as pure alcohol is used as medium.

Shellac works quite well, if, indeed, a primer is needed at all. I've never sprayed it because I've always assumed that the atomization of it coming out of an airbrush would cause too great an evaporation rate for it to work, but perhaps it does. I've never had a bit of problem with 'steaks from brushing on." That's assuming that one isn't using too heavy a cut. (I usually apply it out of the can, which, with Zinsser, at least, is two pound cut, I believe.) I often don't brush shellac at all, actually. I just dip the piece into the can, remove it and give it a shake to remove the excess and then, if necessary, us the point of a paper towel to soak up the remaining shellac in the nooks and crannies. With wood, I do the same, wiping off the excess with a piece of paper towel. Shellac is the most forgiving of all coatings. If you mess it up, just dip it in some denatured alcohol ("meths") and wipe it off, let dry, and re-coat.

 

I've never noticed any adverse effects from alcohol vapors, although I don't spend a lot of time intentionally inhaling them and I always provide good ventilation out of concern for the hazards of combustion. In light of your comment and what I recall to be your background in chemistry, I looked it up and found that when alcohol vapors are inhaled, the alcohol  is absorbed in your lungs and completely bypasses your digestive system. Alcohol molecules are then transported directly from your lungs into your bloodstream and brain. Inhaling alcohol can harm the brain, lungs, and intoxicate someone very quickly. Apparently, it can be abused. When people smoke alcohol, they heat it up to intensify the vapor, or they pour it over dry ice, according to the literature . This makes a strong vapor which they inhale into their lungs. I worked for nearly a decade in San Quentin Prison and I have a professional background in substance abuse issues spanning close to fifty years at this point, so I thought I'd seen it all, but I've never heard of anyone "smoking" alcohol or pouring it over dry ice. (Convicts are quite creative in finding ways to intoxicate themselves, as you might imagine!  ) I suppose those are techniques employed to extract the alcohol from otherwise non-consumable sources such as hair tonic, mouthwash, or the like. Oddly enough, I've cooked a lot of meals aboard boats with alcohol stoves and never noticed any ill effects at all. I expect that while alcohol vapors are toxic, one needs to be exposed to a substantial amount of them in a high concentration to suffer any ill effects. As with all hazardous materials, commonsense is the user's first and most effective line of defense.

[aymodeler]

I was originally thinking Binz, which is a shellac based primer, but decided to give the Tamiya spray primer a try. I don't currently have an airbrush (and these parts are a bit small for my HVLP setup 😀), so I will brush on Tamiya flat black. I only have a few small parts (one cannon, 2 anchors, and a few other small parts).

 

If anyone is interested in seeing the kind of finish you can get with good old shellac, look for a video on applying "french polish". This is essentially a process of wiping on many, many, many super thin coats of thinned shellac with a linen pad. The end result is a deep gloss that will put any modern polyurethane finish to shame!

[Bob Cleek]

10 hours ago, aymodeler said:

If anyone is interested in seeing the kind of finish you can get with good old shellac, look for a video on applying "french polish". This is essentially a process of wiping on many, many, many super thin coats of thinned shellac with a linen pad. The end result is a deep gloss that will put any modern polyurethane finish to shame!

 

So very true, however, all that hand rubbing can go to hell in an instant if somebody spills so much as a drop of an alcoholic beverage on it!   I love shellac for all sorts of purposes, but the polyurethanes do have their advantages on furniture, particularly table tops.

[aymodeler]

3 hours ago, Bob Cleek said:

 

So very true, however, all that hand rubbing can go to hell in an instant if somebody spills so much as a drop of an alcoholic beverage on it!   I love shellac for all sorts of purposes, but the polyurethanes do have their advantages on furniture, particularly table tops.

 

Agreed. I use shellac on smaller, decorative pieces. There is something about the look and even the feel of a traditional shellac finish that gives a handmade piece a sense of warmth and even soul that cannot be recreated with poly finishes. But acrylic poly is my go to for anything that needs to stand up to daily wear and tear, and with a good HVLP setup, it is fast and easy to apply.

[Bob Cleek]

6 hours ago, aymodeler said:

There is something about the look and even the feel of a traditional shellac finish that gives a handmade piece a sense of warmth and even soul that cannot be recreated with poly finishes.

Unfortunately, the knowledge of how to maintain a fine French polish on a piece of furniture is totally lost on the homeowners of today. The same is true of hand-rubbed finishes on varnish and oil-based paints. 

[Snug Harbor Johnny]

I have crafted several 'heirloom' pieces of furniture made of Honduran mahogany, and the only finish I considered was a traditional French Polish with shellac - and I dissolved my own dry orange shellac flakes in Ethanol, but if you can find Zinnzer orange shellac in an unopened can not more than a year old it will do (they use methanol as the solvent).  It takes weeks to slowly build and level enough layers (with a lint-free cloth bag containing absorbent material, then abrading with rottenstone or 600 grit paper when each application has had a day or two to cure) to gain what is known as chatoyancy - a jewel-like luster not unlike cloisonné enamel work.  Once finished I applied only a very small amount of paste wax.  No 'maintenance' is required - unless someone leaves an alcoholic beverage glass on a horizontal surface that leaves a 'ring'.  Then it is a case of a repair to blend out.  My 25 year old pieces look as good as the day they were finished, except that the underlying mahogany has darkened naturally with age.  BTW, fine furniture should not be exposed to habitual UV radiation (sunlight).