For the last (hopefully) time, how to decant spray paint.

[Lemosteam]

FOR THE LAST TIME (as far as I'm concerned!)

Backstory:
So I came across a seven can stash of Floquil Zinc Oxide at a hobby shop. Never having used it before, I sprayed a model I was working on. Needless to say, I was extremely disappointed. The nozzle applied the paint so thick, I had to stop the model.

I started to scour YouTube and I came across a YouTube video for decanting paint as this color is extremely rare (and recommended as PRR Freight Car Color. Let's just say that ALL the fears of puncturing a spray can come to mind.

Before you leave in disbelief, thinking there is paint and shards of can I'm my forehead, read on.

You see the paint in the bottom of the can seals the straw and prevents any fluid from exiting through it, which is why I removed the nozzle. The propellant is trapped between the top of the can and the top of the paint surface, so allowing the propellant to escape simply releases the pressure inside the can.

The process seemed sound as I watched, but I decided to try my own version, and was surprised and very happy when complete.

The first step is to let the can stand upright without being disturbed for 2-3 days. Do not shake or invert the can when transporting it to a ventilated location.

Here is the can (I had already punctured it before I decided to document, but here are the steps). BE SURE TO REMOVE THE NOZZLE!


This picture shows the hardened point tool I used to slowly force a puncture into the can. A scratch awl would be better (easier on the palms), but I could not locate mine. DO NOT try to drill or strike the hole into the can.


Insert the can inside a plastic grocery bag and pull the bag taught over the can.


Using your pointy tool, push and rotate the tool into and through the top of the can.


When you feel you have fully punctured the metal, remove the tool and allow the propellant to escape, yes the bag will puff. I assume larger cans will expel the propellant longer, this can took about 3 seconds.


Next, puncture three more holes in the opposite side of the can from the first hole. Stir the contents carefully using the ball bearing to loose any thickened paint at the bottom of the can. Be careful, some paint may come out of the holes.


I decided on this 8 oz Mason canning jar to store the decanted paint into.


Pour the contents out through the first punctured hole (so The paint does not block the anti-vacuum holes on the opposite side).


Leave the decanted paint uncovered through the next steps, to allow the paint to de-gas for a bit.


Using tin snips cut most of the way around the can top.


Pry up the lid to allow you to drop the ball into the Mason jar.


Dispose of the cans in the bag.


Place the canning seal (lid) UPSIDE DOWN TO AVOID SEALING THE JAR FULLY. This allows the paint to de-gas further.


Lightly screw the lid over the canning seal, but DO NOT TIGHTEN. place the jar where it will not be disturbed.


The author directs one to check and re check the pressure levels in the storage jar or the paint can explode out of the jar.

This is critical. On a different attempt using a tube on the nozzle, I filled a Tamiya small paint jar. I went to use it a day later, and got sprayed with Tamiya TS-6, but it was not just a spray, it was like a mini volcano erupting out of the jar and I lost half of what I decanted all over me, and my workbench.

[NorsemanJack]

Why couldn't you just hold the can upside down while pressing the nozzle to release all of the propellant?

[peteski]

There are several methods of decanting spray can.  This one is interesting.  I still use the nozzle with a tube method.

I would not attempt your method.  I'm actually surprised that the paint (with the propellant still dissolved in it) didn't "boil" over and start coming out of the hole you punctured in the can.  Also keep in mind that the propellant is a highly flammable gas which is released all at once.  I would not recommend doing this indoors, especially if it is a basement with sources of ignitions like a pilot flame on a water heater, or other sources of sparks.   I'm probably overly cautious, but I don't think that is a bad thing.  I recommend doing this outdoors.

I absolutely agree that it is very important to lat the pain de-gas.  It seems that the propellant (probably liquefied propane) is mixed with the liquid paint and it takes a while for it to evacuate from the paint.

[Lemosteam]

Why couldn't you just hold the can upside down while pressing the nozzle to release all of the propellant?

It would take forever, and you risk paint getting into the straw.  This took me minutes.

[Lemosteam]

There are several methods of decanting spray can.  This one is interesting.  I still use the nozzle with a tube method.

I would not attempt your method.  I'm actually surprised that the paint (with the propellant still dissolved in it) didn't "boil" over and start coming out of the hole you punctured in the can.  Also keep in mind that the propellant is a highly flammable gas which is released all at once.  I would not recommend doing this indoors, especially if it is a basement with sources of ignitions like a pilot flame on a water heater, or other sources of sparks.   I'm probably overly cautious, but I don't think that is a bad thing.  I recommend doing this outdoors.

I absolutely agree that it is very important to lat the pain de-gas.  It seems that the propellant (probably liquefied propane) is mixed with the liquid paint and it takes a while for it to evacuate from the paint.

Had the same fears.  Nuttin.  I was out in my garage. See the hole is slowly added and like a needle valve releases the propellant.  I was very careful not to disturb or shake the can in any way.  Letting it sit for three days let the paint settle from the propellant.  It just works man; beautifully. I was literally blown away.

[wvgca]

i have been doing this for maybe six or seven years now ... works great into a host bottle .. didn't try leaving it sit a while though ..

[peteski]

Had the same fears.  Nuttin.  ...  It just works man; beautifully. I was literally blown away.

Hmm . . . I'll think about it.
No, you weren't blown away - you could have been if you were doing this in a small sealed room and you lit a match. 

One of the reasons I decant using the nozzle with a tube attached is that I often only decant enough for my current pain job. I keep the rest of the paint in the can (where it is safely stored for later in a metal container).

[wvgca]

if it matters, i've only tried krylon, the regular spray bombs ...
they're supposed to have a non flammable propellant, small sealed room with a cigarette going, lol

[peteski]

if it matters, i've only tried krylon, the regular spray bombs ...
they're supposed to have a non flammable propellant, small sealed room with a cigarette going, lol

Nice!
Krylon makes many different paints. Could you point me to the specific paints you use?

[wvgca]

could I point you to the paints ??
well, kinda, it's been a few years, lol ......   they were the full size spray bomb, plastic compatible on the label ..
colours were a medium brown, a dark yellow, and a reddish brown [dark rust ] ..
I don't have the spray bombs any more, but think I've still got the 'mixed' plastic
gatorade bottle of the mix sitting around yet .. it 'settles' out fairly quickly   .....
I put it on the track rails with an airbrush, no need to thin the mixture .. and scraped the top of the rails off later

[craigolio1]

Hmm . . . I'll think about it.
No, you weren't blown away - you could have been if you were doing this in a small sealed room and you lit a match. 

One of the reasons I decant using the nozzle with a tube attached is that I often only decant enough for my current pain job. I keep the rest of the paint in the can (where it is safely stored for later in a metal container).

Yup. I just shoot down a McD’s straw into the colour cup of my airbrush. This looks like a decent procedure though if one needs a lot of paint at once, as my method is a pain if painting a large batch of models.

Craig.

[nickelplate759]

what do you clean the airbrush with after spraying Krylon or Rustoleum?

[craigolio1]

what do you clean the airbrush with after spraying Krylon or Rustoleum?

I use lacquer thinner.

[peteski]

what do you clean the airbrush with after spraying Krylon or Rustoleum?

You might find my cleaning method helpful for any organic solvent based (stinky) paints.  See https://www.therailwire.net/forum/index.php?topic=41067.msg511017#msg511017 .  Heck, read the entire thread. 

[peteski]

Yup. I just shoot down a McD’s straw into the colour cup of my airbrush. This looks like a decent procedure though if one needs a lot of paint at once, as my method is a pain if painting a large batch of models.

Craig.

I take this one step further, producing a less messy process.  Over the years I have accumulated many different nozzles (there are several different sizes and types used on aerosol cans). I have also collected a number of tubes from various spray cans.  The thin ones are from cans of WD40, "canned air" sprays, and Electronic "freeze-sprays".  The thick ones are the actual siphon tubes I extract from various empty aerosol cans.  They all come in handy.
Some nozzles were ready to use, while others I had to drill out or otherwise modify to accept the tubes.

Now I have an arsenal of decanting nozzles for pretty much any spray paint that is out there.  The neat part is that since the tube is tightly connected to the nozzle I don't have to worry about having to spray into a straw - I just point the tube into a jar and spray away.  No mess, no fuss.



To clean the nozzle I insert the nozzle's end which normally goes into the valve into my nylon pipette (also shown in the photo).  Then I put the end of the tube into a small partially-filled shot glass of lacquer thinner and I alternately suck and expel the thinner through the nozzle using the rubber bulb on the pipette. That rinses the nozzle and tube clean. Make sure to do this right after decanting, so the paint in the nozzle is still liquid.  Neat and clean!