[gdoc]

I want to coat a bunch of pieces of brass with a very thin, even layer of wax.


Problem #1: Smearing the wax on by hand is tedious. Ain't nobody got time for that.

Solution #1: Dissolving the wax in a solvent, spraying the solvent, and letting it evaporate is a lot easier. The wax needs a non polar solvent of course; hexane works very well. Spraying the hexane on the brass distributes it evenly, and the hexane evaporates quickly. Problem solved. Naturally, this is a job for the well-ventilated great outdoors, away from flames.


Problem #2: Ordinary plastic pump-style spray bottle nozzles tend to deteriorate and melt into soft plasticy sludge when hexane comes into contact with them.

Solution #2: An aluminum bottle with all metal parts for the spray nozzle and valve. These kind of spray bottles don't have a pump style spray mechanism. Instead, you pressurize them with air. The one I have is rated to function at 80-150 psi (max 200 psi). Neat.


I'm not real interested in creating Problem #3: putting hexane under 80 - 150 psi of air pressure adds a whole bunch of oxygen into a confined space with a rather flammable liquid, which might lead to Problem #4: my admission to a burn ward.


Questions:
1) Pressurizing with air would be dumb, correct?
2) Would using CO2 or nitrogen as the pressurizing gas be safe?
3) Is there a less volatile solvent than hexane that would readily dissolve wax, be thin enough to spray easily, and yet still evaporate in less than an hour or two?
4) Is this a really stupid idea and should I abandon it entirely?

Thanks.

[Enthalpy]

Welcome, gdoc!

My elements of answer, keeping in mind that several advices are better than one, more so about safety.

CO₂ is almost liquid at 13bar and room temperature. I'd prefer N₂.

Light hydrocarbons like hexane and gasoline dissolve polyethylene and polypropylene, but other plastics resist it. A paddle spray bottle is safer than a gas-pressurized one, if you find some of proper materials.

The spray itself is very badly dangerous, much more than the vapour+air mix in the bottle. I played enough with that as a teen to tell you positively. Not only hexane is a bad idea to spray: I achieved huge flames with lamp petroleum (which wouldn't catch fire with a lighter, only if in a spray) and even with molten sprayed wax.

Since I know you will try it anyway: please be careful, do it outdoors, keep everyone away from the flame, and so on. Mind the radiated heat.

Could you dip your brass parts in molten or dissolved wax, instead of spraying?

Yes, some liquids dissolve wax, evaporate reasonably quickly and are still hard to light if not sprayed. You just need molecules a bit bigger than hexane. Lamp petroleum should work, other hydrocarbon solvents (I got "branched alkanes C₉ to C₁₃" from the hardware store) too. Avoid Diesel oil as its vapours are unhealthy, and stay away from all other vapours.

Depending on you needs, you might replace wax with a more durable coating. This includes polyethylene: dissolve filings in lamp petroleum or similar.

[gdoc]

The spray itself is very badly dangerous, much more than the vapour+air mix in the bottle. I played enough with that as a teen to tell you positively. Not only hexane is a bad idea to spray: I achieved huge flames with lamp petroleum (which wouldn't catch fire with a lighter, only if in a spray) and even with molten sprayed wax.

Yeah, not at all interested in building a flamethrower. 

Could you dip your brass parts in molten or dissolved wax, instead of spraying?

Not really. I probably should've given more application details in the OP. The cardinal sin of asking for help on the internet is to ask about methods while being short on the desired result / application.

The brass parts are actual pieces of brass ... as in empty, cleaned, ammunition cartridge brass that is destined to be reloaded. The purpose of the wax is to lubricate the surface so they don't get stuck in resizing dies. This requires an extremely thin coat of a particular wax (this product).

Presently I'm just handling each piece individually and waxing them with my fingers. This is very slow. Most people who reload brass cartridges use other lubes. Spraying lanolin disolved in 99% isopropyl alcohol works but lanolin is sticky and makes a huge mess. Wax is a significantly better lubricant and cleans up easier. The problem is that it's a tedious hassle to individually handle 100s or 1000s of pieces of brass to apply the wax.

There is one commercial aerosol spray lube on the market for this purpose, but it's terrible. Not very slippery so sizing is inconsistent, and it and tends to get presses locked up when brass cases get stuck in resizing dies.

I'm looking for a better option.

Yes, some liquids dissolve wax, evaporate reasonably quickly and are still hard to light if not sprayed. You just need molecules a bit bigger than hexane. Lamp petroleum should work, other hydrocarbon solvents (I got "branched alkanes C₉ to C₁₃" from the hardware store) too. Avoid Diesel oil as its vapours are unhealthy, and stay away from all other vapours.

Depending on you needs, you might replace wax with a more durable coating. This includes polyethylene: dissolve filings in lamp petroleum or similar.

Thanks. I need to efficiently apply a very thin coat of a particular wax, by spray on a huge number of small pieces of brass. Durability is undesirable - the wax needs to be removed after the resizing operation.

If spray application can't be done safely then I need to abandon the idea and just keep using my fingers.

Reloading a rifle cartridge is, essentially, building a small explosive device that will be deliberately detonated a few inches from one's face. We're a meticulous and safe group of people in general because we like our eyeballs and fingers ... so if hexane/wax spray is fundamentally unsafe I won't push that envelope.

I shoot many many thousands of rounds per year in competition and practice, and reloading requires significant time. Looking to make one stage of that process more efficient.

Thanks for your input!