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new needle seal (o-ring) testing

Discussion in 'Airbrushes' started by Vladimir, Nov 19, 2018.


  1. Vladimir

    Vladimir Detail Decepticon!

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    Many long term users of the airbrush tool know that old airbrushes came with rubber seals for the needles. Now most ABs have Teflon (PFTE) needle packing. These two types of the needle seal have their pros and contras. Great advantage of the rubber seal is its smoothness that gives great feel of the needle movement while painting. We mentioned for many times here on the forum how old type of the O-rings (rubber one) smoothly work. But there’s big disadvantage here also. Rubber can’t bear the solvents. This feature does not allow to use urethane paint for airbrushing, while watarbased paint is no problem. On the other hand we have teflon packing that is completely solvent proof and so extremely durable, that will serve for decades at least, if not for entire life of the airbrush. Disadvantage of this type of the seal is material properties. Teflon is very slick material, but it is much harder than rubber.
    O-ring for sealing the needle has different shape as you can see from the photo. As a result, we have bigger contact area of the seal and the needle, than in the case with the rubber O-ring. This affects the needle movement.

    P1010004.JPG

    Another thing about two types of the seals is tightening the seal inside the AB body. For the rubber O-ring you need just screw in the packing nut almost without tightening and the needle is perfectly sealed, while with the teflon you need to find sweet spot between good seal and good movement of the needle. Low tightening and you will have paint leak, if you have slightly more tightened packing, the result is stiff movement of the needle.

    Funny thing happened when I bought my first old micron, old microns all came with rubber O-rings from the factory. I figured that out while cleaning the Ab after some test spraying. I used urethane paint for that and cleaned the brush after with the urethane basecoat thinner. I felt that something liquid started to run over my fingers. I thought to myself then: I have cracked body!:) I didn’t remembered then that old ABs had rubber O-rings as the needle packing. And the thinner on my fingers was very good reminding.

    I have some old ABs and all of them have rubber O-rings as the needle packing. The fact that I use only urethane paints for airbrushing does not allow me to use rubber packing, so I ordered custom made teflon packings. You can see them on the photos. Some are treated after the lathe work and ready to use, and some are rough and untreated. Definitely, in old ABs I have custom teflon packings installed and they work as other good teflon solvent proof packings do.

    P1010007.JPG

    Besides that I ordered some custom made packing nuts to play with, but never did the test. What do you think would be the best, shorter or longer variant? Original one is the first on the left, any other is custom made.

    P1010005.JPG

    BTW, small tip on the toothpick. You can use them as the O-ring and seal packing nut install tool (and removal also).
    Without the sharpening the toothpick tip you can clean 0.5mm nozzles (Eclipse).
    It’s just a tool I use in ABing since the first day of my ABing:)

    One thing I couldn’t forget is the softness of needle packed with the rubber O-ring. This feature isn’t that important in background painting or for not detail work, it doesn’t really matters how you feel the needle movement or starting the spraying at these kind of work.
    But when we talk about detail illustration freehand work, where you need precision, the teflon seal is far away from soft and predictable spray start (the trigger response) compared to the rubber seal.
    We have also talked here on the forum that it would be great to have soft and solvent proof seal for the needle, as many of us require that precise spraying from the detail airbrushes and not everybody uses waterbased paint.

    Recently something with these desired features has appeared on the market and available at Rockett Airbrush. I got some new type O-rings not so long ago from there and started to test them.

    How new O-ring looks you can see on the photo. It's on the right alone and the other are old type O-rings on the left (many).

    P1010006.JPG

    I have to say, it’s not complete test with the conclusions made, but testing in process. I think, it would be interesting for everyone to watch how the things go not knowing the end result. I do know it either.

    What I expected from newly released product is soft feel and solvent proof seal.
    I can say just now that it is as soft as rubber seal is, it’s just the same smooth at work.

    As the urethane paint for couple of days is in the airbrush and nothing like paint is seen through the micron airbrush window in the AB body around the seal, I could presume that it’s also solvent proof.

    I didn’t now what airbrush to choose either HP-SB+ or CM-SB, but when it came to changing the seal CM-SB stood aside as it has built in teflon seal in the packing nut itself. I have no idea how to normally remove it and remembered that I have another microns with different packing nuts, so my test gun is MP-200A.

    P1010008.JPG

    Here's the suggestion for Rockett Airbrush: to think over manufacturing the needle packing nut for new type of microns to use with new O-rings.

    On the smoothness for detail work and the trigger response I can say that’s it, just as I wanted! Just great! Now I don’t guess when the paint would start going through the nozzle, but I just look at the place where the paint will lay down. No expectation for the paint flow start and anything, just normal work. The needle movement becomes the continuation of your finger movement, what would you need more! It’s like your fingertip is on the needle tip and there’s no trigger or the seal resistance in the AB. It’s like sniper’s rifle that throws bullets exactly where you see through the optics, so does your airbrush.

    Next moment is the solvent proof features. I can’t say from the start how well it is solvent proof.
    As for making the conclusion on this property we need time.
    One thing that will help to estimate this feature is the dimensional stability of the material exposed to the basecoat thinner in the paint. I’ve made the measurement of new O-ring as it arrived from the seller. I will remain the paint in the airbrush for more than a week, what I’d do with ABs while making custom paint job, and will make the measurements of the O-ring again after the AB cleaning. I think the results will be representative.

    The measurements as you can see them.

    P1010003.JPG P1010002.JPG

    Another thing that we should expect from the product is its durability, as we have constant friction of the needle and the O-ring and I wonder for how long the material would bear this friction. I mean it’s all about the product lifetime, or at least for how long this seal will be giving good and expected work of the seal.

    BTW, the test was done with some other custom parts installed in the AB and I like the results not less than I like the results with testing of new O-rings. Will post a thread later, I think.

    That’s it for now. To be continued.
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  2. Robbyrockett2

    Robbyrockett2 Air-Valve Autobot! Very Likeable!

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    You can use the old style packing nut, (which you can get packaged with the new seal) or follow the link on the product page to @DaveG 's instructions on modifying the new style packing nut.
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  3. Vladimir

    Vladimir Detail Decepticon!

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    I used it this time. The question was about new microns, I meant Iwata CM series. No problem with old airbrushes where you can just remove old O-ring and install new one there.

    One thing I forgot to mention. After having smooth action I realized that I would need harder spring of needle mechanism than the stock one. It would be better for more precise freehand detail work.
    In the air valve I have soft springs installed.

    I'm not registered on fb and I see a banner on 1/3 of the screen so reading smth on fb, even if the page is open to read, is not comfortable to say the least. From the fb page that linked to the product page (O-ring+packing nut) I see only one photo with the nut that has smth like teflon inside, just as random teflon packing of not CM airbrushes.
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  4. Robbyrockett2

    Robbyrockett2 Air-Valve Autobot! Very Likeable!

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    You can buy a seal and nut together as a package that can used w the new micron (which is simply the old style nut I-565-1) or modify the existing Teflon type.

    On the Facebook instructions you just have to scroll to the next pictures.

    I think we can put together a PDF once the wording is all put together though.

    Essentially it's just cutting the Teflon off flush and making the original hole larger so it doesn't touch anymore.

    As seen here

    45627591_1794500513988862_7404152494474919936_o.jpg
    Last edited: Nov 19, 2018
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  5. SiRoxx

    SiRoxx Party Boy UK Style Very Likeable!

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    Definitely interesting to see the product being tested.


    Sent from my iPhone using Tapatalk
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  6. Robbyrockett2

    Robbyrockett2 Air-Valve Autobot! Very Likeable!

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    If there's any success with these I'll probably have some made with side slots like the newer version though.
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  7. DaveG

    DaveG Detail Decepticon! Very Likeable!

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    You can simply trim the teflon protrusion off of the Micron style retaining screw, ream a little with a toothpick to make sure your teflon is not needle bound, and then reinstall with one of the Dura-Glide O-rings in place. The O-ring will keep the teflon from being distorted and binding against the needle.

    I do not know if Robby also included some of our new lube, but when used in conjunction with these seals, the feeling at the trigger is sublime. If not, I will make sure we get you some...
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  8. DaveG

    DaveG Detail Decepticon! Very Likeable!

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    I should also mention, having had to design high pressure seals (up to 5000psi working pressure) and testing a gazillion different o-rings and seal materials, the way an o-ring is designed to work optimally is really quite simple. You can fool around with different retaining screw shapes and contours, but doubt you will find one that yields any appreciable results that are better than the original screw. It simply is not needed.
  9. Robbyrockett2

    Robbyrockett2 Air-Valve Autobot! Very Likeable!

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    I was just clarifying all this w Dave, I'll change the site around to be more clear and add the micron specific combo.

    I-565-1 nuts/screws will come w iwata micron/770 seal combos.

    For any other combo including olympos microns or any hp series style the combo will come with iwata I-125-1

    Thank you for bringing the issue to light.

    There is still always the possibility of modifying your original Teflon seal....even if it's wore out in order to save yourself a little cash.

    We don't markup the nuts/screws at all and the combos are offered for your convenience.
    Last edited: Nov 19, 2018
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  10. Robbyrockett2

    Robbyrockett2 Air-Valve Autobot! Very Likeable!

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    You must now select your option in the seal and screw combo on the store site in order to get the proper packing screw with your set.
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  11. SiRoxx

    SiRoxx Party Boy UK Style Very Likeable!

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    Having a PDF or some sort of guide available would be a great idea. I haven’t seen the inside of mine to that degree, so I’m having trouble following the issue with the Micron type, I’m sure pics would make it obvious though.


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  12. Robbyrockett2

    Robbyrockett2 Air-Valve Autobot! Very Likeable!

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    Now that I looked at it a little more I think those were intended to reduce the amount of contact his custom teflons had to make with the needle.
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  13. Vladimir

    Vladimir Detail Decepticon!

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    You're right!;) The size is to reduce the amount of the contact. All you see were first experiments. I should order even smaller size, but taking into account that I don't have my lathe running yet, the experiments will happen not very soon. Moreover, these new O-rings are smth that maybe stop me thinking about the experiment with the teflon.

    So, for today urethane paint is in the cup for 15 days.
    From time to time I came to my studio to check up the things and shoot some paint. I can only say that the feel of the needle movement is the same as it was in the beginning and no paint was seen somewhere outside the O-ring.

    I also installed new O-ring into another airbrush, chinese one with 0.3mm setup. Results are the same as with the micron. I mean the needle work, but not the line pattern:) Though, the AB itself is very good at work.

    For today I planned to finish the testing, to clean the AB and the O-ring and to make measurements of the diameter. But this morning's surprise does not allow me even to get to the studio.

    P1010005.JPG

    Now I have to clean up everything up. It's made weekend, not only my day:D As the yard should be also cleaned:(
    So within some days the path will be clean enough to get inside the studio and to finish what I intend.
    Updates are coming soon!
  14. DaveG

    DaveG Detail Decepticon! Very Likeable!

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    I have had samples of these o-rings soaking in containers off Lacquer Thinner, Acetone, and various Alcohol solutions since October 20th - and have not yet observed any appreciable difference in form or function. I suspect you will find no issue when you do make it back into the shop.
  15. Vladimir

    Vladimir Detail Decepticon!

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    Dave, the more people testing the thing, the more objective feedback we have:)

    From what I'm experiencing now, I expect at least not much change to the material the O-ring is made with. If there's any change to it, that's also possible. Micrometer will tell exactly, it's not biased;) My finger can't feel the difference between the first minutes of use and after two weeks, needle movement is all the same with soft and predictable spray start. That's really cool to have such a work of the tool.

    BTW! Does anyone made an experiment with measuring teflon seal "dry" and after soaking it in the urethane basecoat thinner? There can be surprise, who knows how it behaves. I didn't do that, that's rather strange.
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  16. Robbyrockett2

    Robbyrockett2 Air-Valve Autobot! Very Likeable!

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    Not specifically.

    Though I honestly had no need.
    Idependent lab results are well documented and more thorough than i could hope to achieve.
    PTFE is actually more suceptible to thinks like;
    Alcohol
    Olive oil
    Butyl ether (4012)

    Showing between 10 and 20 percent swell at 40c with this chemicals.

    Urethane reducer shows less than 10 percent swell.

    The material these orings are made from has nearly identical results to ptfe. With some variance, so that with a given chemical these orings could be slightly more or slightly less compatible compared to PTFE .
    For our intents and purposes the behaviors of the two could be considered identical.


    Though I welcome outside testing...I love it in fact!
    Any testing that could be seen as non biased or less biased than our own claims or demonstrations I am confident will only strengthen the claims.
    Last edited: Dec 1, 2018
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  17. Vladimir

    Vladimir Detail Decepticon!

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    Behavior concerning the chemicals you mean. For their "mechanical" part is totally different.

    One thing is the lab and the manufacturer, another thing is those who intend to use the product being tested:)
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  18. Robbyrockett2

    Robbyrockett2 Air-Valve Autobot! Very Likeable!

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    Exactly.

    Just meaning I haven't bothered measuring PTFE swell with certain chemicals.....it's too easy to just look at lab results for that.
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  19. Vladimir

    Vladimir Detail Decepticon!

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    I just need to guess that:) Often I make thing complicated.
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  20. Vladimir

    Vladimir Detail Decepticon!

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    So, today I'm done with the testing!:)
    The urethane paint was inside the cup for 17 days reduced with slow basecoat thinner.

    After some final shots of the paint I cleaned the AB and removed an O-ring. It was a surprise to have that feel when removing the needle, so soft compared to teflon packing, that I need to get used to it.
    Movement of the needle was the same smooth as it was in the beginning of the experiment. Read the first post in this thread how works and feels. I have nothing to add.

    The measurements.
    Were done with the same tool, same needle, same O-ring before the test and right after, when the AB was cleaned and the O-ring removed.
    What I saw surprised me. You can see it on the photo.
    Diameter of 3,031 in the beginning and 3,037 in the end. I have not expected to see that, honestly I expected another result. The difference is about nothing. One can not feel this difference in the needle movement.
    The O-ring looks like it was new. You can also see it on the photo.

    P1010001.JPG P1010003.JPG

    What I think now about this product? I will buy to install these O-rings in my detail airbrushes. High recommendations for everyone to try. Just buy one O-ring and then decide;) For I want have these O-rings in my ABs.

    And some things translated into Airbrush language:)

    1a.jpg

    1.jpg

    2.jpg

    3.jpg

    5.jpg

    6.jpg

    It was just for fun, no intentions to get crazy about precise pictures, just like fast drawing with a pencil. The things are small as it's 0.18mm Olympos nozzle, that in reality has smaller diameter than Iwata's 0.18. I also didn't go crazy about the right paint reduction, I had another goal.

    As I've already said above due to the soft O-ring installed airbrush starts spraying just where you need it to. That's really great feature. You will understand me if you will change your teflon packing for this type of solvent proof O-ring. Your experience is the best answer.

    One thing remained is to know how the thing is durable. I can't say it in two weeks of usage. Only time will show. Any other characteristics are just great.

    The end of the experiment.

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