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Thread: Fixes for blocked paint spray can sprayheads

  1. #1

    Default Fixes for blocked paint spray can sprayheads

    Seems every time I go to use a paint spray can, after 1-2 minutes of agitation, the sprayhead or something blocks the spray after an inital release of paint. I scrap paint and debris from around the orifice in the sprayhead and try soaking it in paint thinner but this is often not successful. I am fearful of turning the can upside down and spraying the propellent out prior to storage and then throwing out the can because of a lack of propellent. What methods have you found to be successful? Thanks Paul

  2. #2
    Join Date
    Mar 2010
    Posts
    151

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    Better to lose a little propellant clearing the nozzle after use than losing the whole rest of the can from a blockage. Most nozzles are interchangable, so pull any unblocked ones off of empty cans before you toss them,so you have a few spares.

  3. #3
    Join Date
    Oct 2007
    Location
    Pleasanton, CA
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    441

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    When you are done with a small job, take off the spray nozzle and blow it out WELL with 100 psi air. Blow off the top of the can too, making sure any paint does not blow back in your face. Saves propellant and cleans much better.

    DJ

  4. #4
    Join Date
    Aug 2008
    Location
    Missouri, USA
    Posts
    1,258

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    Keep spares.

    REPLACEMENT_NOZZLES

  5. #5
    Join Date
    Oct 2009
    Location
    South Florida
    Posts
    194

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    I take the head off, and stick it on an old can of carb cleaner I keep for the purpose. A little spritz cleans out the head, and I put it back on the paint. I also never throw away a usable spray head, they often can save a bad clog.

  6. #6
    Join Date
    Aug 2001
    Posts
    527

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    Ditto the advice to flip the can over and clean the nozzle.

    That said, I keep two pin vises with small drill bits. One fits inside the stem of the nozzle. The other, much smaller, fits the spray opening. This is the only way I've found to get paint out after it has hardened.

  7. #7
    Join Date
    Jan 2003
    Location
    Chilliwack, B.C.
    Posts
    9,207

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    On occasion, I back-fed some brake clean through the existing nozzle and tube. That worked to make the can usable again.

    It's going to be a battle of the pressures- whichever can has higher pressure will feed into the other. The problem as I see it is that paint will remain in the tube inside the can and not get mixed as you shake the can. When you begin spraying, that part of the paint will quickly migrate into the nozzle and clog it. If you are able to blow that backwards and thus clear the entire pathway, the mixture can then be entirely mixed and should spray out fine. I suppose you really should know what the particular propellant is, so you can use the same stuff for the back-feed.

    Very often the propellant is a mixture of propane and some lighter gasses. For sheer availability, propane would be my blow-back gas of choice. You would want to be able to pump a known, fairly small quantity of it back into the can. I've thought of making an injector device which might hook up to a standard propane cylinder, either the tall or the stubby 1 lb size. To use it you'd connect to the cylinder, let it charge, then disconnect from the cylinder. After securing it to the spray head via a short section of tube, you'd press the spray head to open the valve, then do one full pump of the injector handle. Whatever gas is in the injector is forced into the can, you release the spray head and disconnect the injector- and you're done.

    If there was a liquid solvent that would make more sense to use, it might be easier. The injector wouldn't be much more than an oil can pump- a fixed amount of 'juice' is expelled per stroke. Because it's a small quantity, the pump could easily overcome the existing pressure in the spray can. If some of that solvent remained within the internal tube in the spray can, it would't take but a few seconds to expel it next time the can is used. That's pretty normal - you'd usually test the output of the can before you pointed it at your project anyway.

    The hookup and procedure is easy. Knowing what solvent to use for the particular can might be the more troublesome part. Then there's the issue of when to do this- just after you're finished using the can for the time being, or just before you use the can again- or at both times.

    This is just an idea- like I said I've tried it once with good results using brake clean. I had nothing to lose since the can was clogged anyway, but I guess the possibility was there for a dangerous interaction between chemicals to occur as well. You'd definitely want a heads up on that beforehand.

  8. #8
    Join Date
    Oct 2002
    Location
    Kirkland, Washington
    Posts
    797

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    There used to be a guy around on r.c.m. named Don Foreman. Don took an old Bernzomatic torch head and unscrewed the flame nozzle at the tip and measured the threads. Then he turned a little cap on his lathe that screwed onto the torch. The outside of the cap exactly fit the stem of a spray paint can. To use it, he'd screw the Bernzomatic onto a bottle of propane, put the paint can in a deep cardboard box, press down and turn on the torch and give it a shot of propane. He said it cleared some clogs but not all.

    I have another buddy who posts on this forum who stores all his spray cans upside down. He figures the solids settle to the bottom and harden there. I've been doing that lately, can't really tell if it helps or not.

    One thing I know for sure is spray paint in cans has a shelf life. Old spray cans, even if never used, nearly always clog on me. When I realized that the light went on and I understood why hardware stores had closeouts on spray paint sometimes.

    To summarize:

    don't store spray cans long term
    shake them really well (I do 2 full minutes timed by my shop clock)
    blow them out after use - never ran out of propellant yet
    if the nozzle clogs soak it in solvent and blow it out with compressed air
    if the stem clogs deep inside blow it out with propane

    metalmagpie

  9. #9
    Join Date
    Dec 2009
    Location
    Stevens Point, WI
    Posts
    4,387

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    I always grab for another paint cans nozzle as well.
    Andy

  10. #10
    Join Date
    Jan 2005
    Location
    Colton, Washington, USA
    Posts
    650

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    I'm guilty of keeping spray paint for too long. No matter how clean the nozzle, solids will settle out and come painting time, will clog things almost instantly, even when the can is shaken for the recommended time.

    I got tired of this game, so I rigged up a crude paint shaker. I hung a cardboard box (Something sturdier would be better, but this was just an experiment.) on bungee cords fastened to the ceiling.

    I put the paint cans in the box, then fastened a portable drill to the outside. Chucked in the drill was a crude eccentric made out of a bolt and a piece of scrap iron weighing about a pound.

    A wrap of baling wired around the handle and trigger was used to adjust the speed. The proper speed will be different for every set-up. It needs to be adjusted for maximum movement, usually a surprisingly low RPM.

    After I let things shake for about a day I got a perfect paint job with no clogs.

    Orrin
    So many projects. So little time.

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