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Thread: Choosing proper activators/reducers for temperature?

  1. #1
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    Default Choosing proper activators/reducers for temperature?

    I am looking at the activators and reducers listed for R-M UNO-HD single stage urethane...and the break point between the fast and medium additives is either 68 or 70 F depending on which copy of their TDS I read.

    So, if they list fast activator and reducer for 60-68 or 60-70F, and then show medium for 68-80 or 70-80F, which is the best choice for 70F? I will be painting in a homemade booth either in my garage or my carport if that matters.

    What happens if you use the wrong one?

    Thanks

    Michael

  2. #2
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    I'd probably recommend using a fast hardener so that you don't need to keep it warm for several days to cure.

    As far as reducer I would ask... What spray gun are you using? If you're applying a very finely atomized coating available from a compliant or conventional gun then I'd probably say go with the medium reducer but if you have a low cost gun or an HVLP I'd probably go with fast to help the so that you don't get too much flow. Of course this all could change depending on your skill level, gun, air movement, temperature etc. The reducer will evaporate fast or slow depending on the application and environment and you want to get the coating to flow as much as possible before the reducer evaporates but not so much that it runs the paint.

  3. #3
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    Thanks Len

    I don't have a gun yet, still learning about them. Since my experience is low (zero) with anything but rattle cans, sounds like fast reducer would be helpful to prevent runs. I will likely buy a lower end HVLP (maybe an Astro?).

  4. #4
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    Default mrennie...

    Quote Originally Posted by mrennie
    I am looking at the activators and reducers listed for R-M UNO-HD single stage urethane...and the break point between the fast and medium additives is either 68 or 70 F depending on which copy of their TDS I read.

    So, if they list fast activator and reducer for 60-68 or 60-70F, and then show medium for 68-80 or 70-80F, which is the best choice for 70F? I will be painting in a homemade booth either in my garage or my carport if that matters.

    What happens if you use the wrong one?

    Thanks

    Michael
    Michael, let me ask you when you plan on painting? I see you live in Canada and am sitting here wondering where and when you expect temps in the 70's on your carport? The main idea is NOT ONLY do you want to spray at a certain temperature, you also want the paint to CURE at that temperature. Say you sprayed at 70 and overnight it dropped to the 30's or 40's, you should expect your job not to look the same as when you painted it. Probably end up looking very dry and the chemicals not fully cured. Be careful what you open yourself up to.
    Since you are just starting out, below is a Christmas gift for yourself to help you through a lot of questions, concerns and show stuff you have not asked or thought about. Check it out below, order it and enjoy. Money well spent for 2 hours of information that would take you years to just get into. Henry

    http://autobodystore.com/videos.shtml

  5. #5

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    There's also good books out there. A lot of people say books don't do a thing for you in this trade but in painting in particular it does wonders.

  6. #6
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    Default

    Quote Originally Posted by mrennie
    I am looking at the activators and reducers listed for R-M UNO-HD single stage urethane...and the break point between the fast and medium additives is either 68 or 70 F depending on which copy of their TDS I read.

    So, if they list fast activator and reducer for 60-68 or 60-70F, and then show medium for 68-80 or 70-80F, which is the best choice for 70F? I will be painting in a homemade booth either in my garage or my carport if that matters.

    What happens if you use the wrong one?

    Thanks

    Michael
    Below is a reply from Dennis to someone else that is really impressive that you need to understand. I copied and pasted it below for you with thanks to Dennis!! Henry

    """It's too cold. 55F is the absolute lower limit with 70F being where most paints are rated. Big trouble if you try to work at 30-40F. The reason is the Arrhenius Function which governs chemical reactions. Most chemical reactions double in speed for each 3 degrees Kelvin in temperature. Get too cold and the reaction is so slow that for all intents and purposes it doesn't happen. If the solvents leave the system prior to the catallazation reaction starting it's all over. Subsequent heating does not help then as the molecules can't flow to combine since they have become a solid mass. Trust me, don't do it. by Dennis N. Schmidt"""

    --------------------------------------------------------------------------------
    Last edited by Dennis N. Schmidt : Today at 12:20 AM.

  7. #7
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    Default Showcar...

    Quote Originally Posted by SHOWCAR FINISH
    There's also good books out there. A lot of people say books don't do a thing for you in this trade but in painting in particular it does wonders.
    I seriously am not busting your balls and know you do a lot with books being in school. But when is the last time you could "SEE" strokes made with a spraygun in a book either in picture or in words? I hope you guys in school get to do or see "hands on" for the stuff you are being taught.
    I won't argue the point about books because I don't know what's out there but you gotta admit, there is nothing better than seeing what you are learning IN ACTION. Do you agree?
    Share with us what books are out there that are current as per the standards of today and where one could find them? Thanks. Henry

  8. #8
    88GT Guest

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    An experienced painter would lean towards the slower activator while a new guy should lean towards the faster stuff

  9. #9
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    88GT, I buy fast reducer and fast hardeners regardless of the time of year. The slower the drying time the more likely to get problems with metallic orientation, runs etc. But then I use guns that allow me to spray a decent amount of paint as opposed to some really slow HVLP guns. If the paint is being applied with a really slow HVLP gun while doing an overall paint job then slower reducers and slower hardeners are necessary (when the ambient temperature is hot -- 80 deg.F + ).

  10. #10
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    Henry:

    You make it sound like it is always cold here!! It is not like my carport is an igloo!

    I plan to do all my paining in the summer, and we get enough days that are 80F that my carport should be warm enough. I do understand the need to keep it at a constant temp long enough for the paint to cure, so if it looks like I will run into trouble I might use the garage instead since it has a heater I could turn on before and after painting.

    One of bodywork books I have that I like the best is "Motor Auto Body Repair". Covers alot of stuff but not very cheap ($100+)

    Sounds like I am on the right track with the quick hardener/reducer, 70F temps, and being a newbie

    I'll look into some videos, I agree "seeing" is an important way to learn.

    Thanks

  11. #11
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    Default mrennie...

    Quote Originally Posted by mrennie
    Henry:

    You make it sound like it is always cold here!! It is not like my carport is an igloo!

    I plan to do all my paining in the summer, and we get enough days that are 80F that my carport should be warm enough. I do understand the need to keep it at a constant temp long enough for the paint to cure, so if it looks like I will run into trouble I might use the garage instead since it has a heater I could turn on before and after painting.

    One of bodywork books I have that I like the best is "Motor Auto Body Repair". Covers alot of stuff but not very cheap ($100+)

    Sounds like I am on the right track with the quick hardener/reducer, 70F temps, and being a newbie

    I'll look into some videos, I agree "seeing" is an important way to learn.

    Thanks
    Let me just say, it's too cold here in Connecticut and we get it from you. You also have to understand that you are a member on this board. To us, that means you are important and I had fears you were attempting to paint a car outside NOW.........people have stated things like that before. We're just a bunch of car and autobody nuts who come here to share and help each other. Take care. Henry

  12. #12
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    I knew you were just teasing....my snowmobile is currently in the carport anyways, so no worries about trying to paint right now.

    Winter is the best time for me to do research and learn, as well as save up to buy tools and supplies. I don't know what I would do with myself if I lived in TX or AZ and had no reason to stop working in the garage for 5 months.

    Thanks

  13. #13
    88GT Guest

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    Quote Originally Posted by Phil V
    88GT, I buy fast reducer and fast hardeners regardless of the time of year. The slower the drying time the more likely to get problems with metallic orientation, runs etc. But then I use guns that allow me to spray a decent amount of paint as opposed to some really slow HVLP guns. If the paint is being applied with a really slow HVLP gun while doing an overall paint job then slower reducers and slower hardeners are necessary (when the ambient temperature is hot -- 80 deg.F + ).
    Hes going to be getting an HVLP, but, IMO the gun speed has little to do with activator/reducer speed. I use a somewhat fast gun (Plus) for metalics and clear and never take that into consideration. I'll be painting a Mustang next week in 55-60 weather (with suplimental heat as needed) and I will be using mid temp activators and reducers.
    Maybe it depends on the paint. hes using SS

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