Find all your DIY electronics in the MakerShed. 3D Printing, Kits, Arduino, Raspberry Pi, Books & more!

Ask MAKE is a monthly column where we answer your questions. Send your vexing conundrums on any aspect of making to askmake@makezine.com. If we don’t have the answer, we’ll scare up somebody who does.

Robert asks:

I use Edge shaving gel and I noticed that some cans will not dispense the gel as a foam while others will. Would it make an interesting project to find out how the spray head is suppose to work and find a way to fix it if it is not foaming the gel?

Dear Robert,
According To Edge’s website, the gel is supposed to remain a gel when it exits the can. Therefore, if it came out foaming on occasion for you, I can only guess that it’s due to an abnormality or defect in the can itself.

For curiosity’s sake, I went ahead and bought a few cans of Edge gel and put them through their paces in the hope that I could replicate the foaming action you speak of.

All three of my seven ounce cans came out as a gel straightaway. But I had the suspicion that perhaps it would start to foam towards the end of the can, so decided to empty one out completely.

Though it produced a lot of gel, after exactly 41 seconds the can simply stopped producing anything. Next I decided to get crafty and try a different spray tip.

I opened the outer casing of the can with a screwdriver and found the tube was not the proper size for a standard aspirator tip (like one you’d use on a spray paint can). So, I gently melted the tube with a lighter and forced the tip in once the tube was malleable enough.

To my surprise, the aspirator tip still produced gel, not foam. My next recourse was to melt and deform the Edge gel nozzle itself.

Unfortunately, the deformation of the nozzle did little to nothing to change the output from a gel to a foam.

In the end, the results are inconclusive as to your question, but I tried my darndest to obtain the results you’re looking for. My suggestion to you is to spray some gel into your hand, then agitate it with the fingers on your other hand until it foams up. I hope this helps.

Michael Colombo

In addition to being an online editor for MAKE Magazine, Michael Colombo works in fabrication, electronics, sound design, music production and performance (Yes. All that.) In the past he has also been a childrens’ educator and entertainer, and holds a Masters degree from NYU’s Interactive Telecommunications Program.


Related

Comments

  1. trkemp says:

    From having used the stuff for many years, I know that toward the end of the can I’d usually get foam for a few days before it gave up and stopped squirting anything. I expect it has to do with air or propellant getting mixed with the gel in the can.

    I always found that it sort of frothed up a bit while I was rubbing it on my face, but I don’t know that the foamy stuff worked any better than the straight gel as far as shaving was concerned.

  2. Bennett says:

    In college we got tons of free trial size samples of Edge. When they were “empty” We removed a plastic stopper from the bottom and watched foamy gel ooze out until there was a punch bowl sized mound of foam. We also discovered that the mound of foam was quite flammable.

  3. The guy says:

    Wow! You’re a brave man, bringing a flame so close to the exposed outlet of a pressurized aerosol container! Seems like, at best, a hospital trip waiting to happen.

    1. The guy says:

      In fact, your 4th picture down almost shows the part on the can where it says “Keep away from open flame”

    2. I should have mentioned in the post that I rapidly waved the lighter back and forth to heat the tip gradually, and didn’t get it close to the can itself. We used to do campfire “fire in the holes” at summer camp with aerosol cans, and it take quite a bit of heat to make one explode.

  4. I actually don’t believe that Edge is an Aerosol can. I have always theorized that it uses a spring/piston type system to expel the gel from the can. I was hoping this article was going to dissect the empty can but no dice :-)

    1. trkemp says:

      My guess is that the gel is in a bag and the propellant is under around the bag. But like you I’ve never chopped one open.

  5. Justin Blair says:

    Can says “gel” if you want foam buy foam…or do as Michael Colombo says “My suggestion to you is to spray some gel into your hand, then agitate it with the fingers on your other hand until it foams up.”

  6. Weyrleader says:

    It seems no-one has thought to try an obvious experiment. Why not try shaking the can to see if agitating the gel inside the can will cause it to foam up. This may need to be done when the can has been used a few times so that there is space inside the can for the gel to move around.

    I don’t use Edge so I can’t try the experiment myself. I would love to know the results.

  7. Neil says:

    I always thought it was to do with water/moisture. If the can had got wet or if the bathroom was particularly humid, the gel would come out a little bit foamy.

  8. smithbob says:

    try the long lasting, cheaper and healthy soap and brush

  9. cde says:

    They have little nubs on the bottom. If you punch it in, all the gel/foam comes out of the bottom. No bags, no pistons, it’s simply compressed air or air-like gas.

  10. really? says:

    The foaming is created by effervescence of the propellant (typically a light hydrocarbon such as propane or butane, also why it is flammable) which is mixed into the gel. with a system such as this it is likely that the liquid propellant has separated from the gel, and as such provides the force required to push the gel from the can, but does not provide the in gel expansion required in order to form the foam. As this is not an aerosol can (it does not form aerosols, (tiny liquid droplets) but rather a foam, similar to whipped cream) the nozzle is of little importance.
    A couple of simple experiments to determine if these are true.
    1. check the listed propellant on the label.
    2. test can before and after heavy shaking (does foaming happen after agitation)
    3. test if the gel is miscible with liquid hydrocarbons, it is likely that the gel has been specifically designed to be at least partially miscible with non-polar (hydrocarbon) solvents, so the foaming action works, and miscible with water such that the gel will wash off with water. Miscibility is the ability of 2 liquids to mix (ethanol and water are miscible, oil and water are not)

  11. rick says:

    Maybe it is an altitude thing? It ends up more foamy if you are in the mountains rather than at sea level.

  12. Paul says:

    My father worked for the company that made the first Edge cans, as a tool and die maker at the Contental Can Corp research plant in Chicago. (early ’60′s?). There is a piston that separates the gel from the propellant. He could get a can filled with any liquid and presurized. Once he had a can filled with vodka, that he took into a hospital to he could mix screwdrivers with his orange juice!

  13. namssorg says:

    I got sick of going through so many of those cans and switched to this stuff years ago. Comes in a tiny 3oz bottle (so you can carry it on a plane!) and it lasts a lot longer since you only use a few drops at a time, mixed with water. Plus, you can see what you’re doing while you’re shaving. http://www.shavesecret.com

  14. michael says:

    I got two cans of the stuff and did not get to use half of either can because they both got a hole in the can and made a great big mess in the bottom of my sink so i will not buy the stuff anymore thats a lot of crap to have to clean up and besides if you cant use it that fast you can only use so much at one time they need to rust proof the can to make it last oh then that would cut down on sales

  15. R M Kaimal says:

    The shave gel is a bag in can product. The gel itself is in a bag which is attached to the valve. It contains Pentane which boils off at around 20 deg C. Most of the time the gel is dispensed at a temperature ( Ambient ) which is around 20 deg C. Hence it comes out as a clear gel. When you rub the gel we are increasing the temperature and hence the Pentane starts to evaporate which foams the gel. The bottom portion of the can contains Nitrogen ( Or compressed air ) which presses against the bag expelling the gel when the button is pressed. If by any reason the Nitrogen has escaped and pressure has dropped in the can then even if the button is pressed the gel will not come out. And if the ambient temperature is more than 25 deg C then the gel comes out as a foam.

    1. well! I’m going to have to verify this, but that sounds pretty legit. Thanks!

In the Maker Shed