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Thread: simple Hi-Tek coating

  1. #14321
    Boolit Master
    Ausglock's Avatar
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    I mix 5 or 6 200ml batches and store in the fridge.
    Colour is fine and never had an issue.
    some will be in there for a few months or so.
    Hooroo.
    Regards, Trevor.
    Australia

  2. #14322
    Boolit Master Avenger442's Avatar
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    Mixed and coated with my oldest powder version Gun Metal last night. Mixed as expected, coated well and looks like it will be as it was the first time I used it. This powder is about six years old. Will report back on the bake, subsequent coats, and how it performs.
    While I work at it, it is by God's grace that it happens. So it is best I ask him what, how and when before I start..

  3. #14323
    Boolit Master


    Burnt Fingers's Avatar
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    I keep the mix in the refrigerator. I used up some two and a half year old mix the other day. It worked just fine. If I leave it out it won't make it through the summer in in North Texas. Clumps up and turns nasty.
    NRA Benefactor.

  4. #14324
    Boolit Master Avenger442's Avatar
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    I had some mixed coating that went solid a couple of years ago. Bottle was not sealed and all the acetone evaporated. It is nearly impossible to get it back into a liquid state. Probably could have ground it up but it was kind of soft for that and probably would have just gummed up what ever I used to grind it. I tried just putting it in acetone. The small pieces dissolved after about a month. But the large lumps were still there six months later.. Eventually just threw it away. Don't have a refrigerator in the basement so cannot refrig the mixed coating.

    My questions were not directed toward the mixed but wanted to know how long the powder itself would keep. I mixed the six year old powder and coated the 9mm and some 45-70s with it. Had to cook a little longer for some reason. The color is off, not due to longer bake, but they pass wipe and smash test. Don't expect any problems but, going to see if the insulating from leading is still there. Loading some time this week or next. Just wondering is the powder unmixed good for 10 years or so. Not really concerned about the color being a little off.

    It will be some time before we can use the range. It has been raining here off and on for a couple of weeks. Range gets flooded. 25 yard range dries up after about a week of dry weather. Water pools on this range due to shooters digging up the ground with their bullets instead of letting them hit the berm. 200 yard range will be muddy until we have about a week and a half of dry weather. It has a wet weather spring running in it. So may be some time to testing of these loads.
    While I work at it, it is by God's grace that it happens. So it is best I ask him what, how and when before I start..

  5. #14325
    Boolit Grand Master popper's Avatar
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    Jatz would be interesting to find the absorption/transmission cure bands of the HiTek. H2O basically has none so drying would be from normal conductive heating from the HiTek coating/alloy temp. Elec. elements work fine but the 'window' needs to be quartz as window glass doesn't transmit long IR very well. Evidently IR cooking is THE way for PC/HiTek commercial cooking. The high specific heat/conductivity of lead is what takes the time in oven.
    Basically appears that IR heats the lead which then melts and cures the coating. So the cure is from the inside to outside as you thought. Like the UV cured stuff, IR cured would be neat as it takes MUCH less energy. HiTek says the chems for UV curing are too expensive for bullet coating.
    Whatever!

  6. #14326
    Boolit Master




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    Quote Originally Posted by popper View Post
    Jatz would be interesting to find the absorption/transmission cure bands of the HiTek. H2O basically has none so drying would be from normal conductive heating from the HiTek coating/alloy temp. Elec. elements work fine but the 'window' needs to be quartz as window glass doesn't transmit long IR very well. Evidently IR cooking is THE way for PC/HiTek commercial cooking. The high specific heat/conductivity of lead is what takes the time in oven.
    Basically appears that IR heats the lead which then melts and cures the coating. So the cure is from the inside to outside as you thought. Like the UV cured stuff, IR cured would be neat as it takes MUCH less energy. HiTek says the chems for UV curing are too expensive for bullet coating.
    Popper,

    As we have initially thought and later confirmed, IR seems to work with heating the alloy, so the alloy actually heats up coating outwards, forcing outwards moisture and vapors.
    With conventional baking, the introduction of coated alloys into an oven, the sudden heat initially seems to make a thin, dense, highly cross linked and cured coating Skin/film on the surface, and, if coating has not been dried adequately, this sealed "skin" can cause the loss of adhesion due to super heated steam formation between alloy and coating, that simply lifts off the coating from the alloy..

    With IR heating does not have the requirement to heat large amounts of air, which has to be constantly circulated to transfer contained heat into the coated alloy. The IR is absorbed by the metal, which is seemingly passing through the coating. It is the heat in the alloy generated by Infra Red that cures the coatings.
    What has also been indicated, that there seems less requirement to dry the coatings well when using IR baking. This is very good for mass production, as it certainly speeds up output, by not having the delay time caused by drying requirements. Jatz can elaborate more on what he has done and discovered. He is coating and baking at very low ambient temperature conditions.
    From what I have heard, this set up with UV curing, seems to take away the need for a separate drying process. It is a major benefit, especially for commercial casters as reduces energy requirements, and may speed up production rates by some 30% or more.

    Due to the strong insulating property of H-Tek, conventional ovens need higher temperatures for longer periods to drive the heat into the alloys.
    You are right, with IR curing, the heat actually travels from alloy outwards, so the insulating property of the coatings is not a barrier but in fact prevents heat loss from alloy, that results with faster curing rates, energy saving and much more even colors, even with overbaking.

    With UV curing, the reins used for UV cured coatings, contain specific chemicals that are activated by UV energy, that starts crosslinking process. I don't know how much heat may be also involved in the UV curing process. I really don't know if UV would work with Hi-Tek as it does not contain any reactive chemicals that would initiate cross linking with UV radiation.
    It is not clear, if UV light to heat alloy, would penetrate coating, without burning the coating.

    I know that sunlight will damage the uncured, as is coating. It is not known, which energy wavelengths do the damage and which ones are beneficial.
    May be that can be another research project, especially if the costs are warranted.

  7. #14327
    Boolit Master
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    "I know that sunlight will damage the uncured, as is coating."

    Can you explain more about sunlight damage the uncured, as it is coating?

    I use a lot of Candy Apple Red and dry the coated in sunlight at up to 140 deg F (60 deg C) for a few hours.

    Should I remove them from the sun light after 30 min?

  8. #14328
    Boolit Master




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    Quote Originally Posted by ioon44 View Post
    "I know that sunlight will damage the uncured, as is coating."

    Can you explain more about sunlight damage the uncured, as it is coating?

    I use a lot of Candy Apple Red and dry the coated in sunlight at up to 140 deg F (60 deg C) for a few hours.

    Should I remove them from the sun light after 30 min?
    Ioon44
    I was referring to product being stored in clear plastic containers which are transparent, and, after many weeks and probably months, it was noticed, that the product film touching plastic container internally had discolored.
    In terms of drying, in full sunlight, many have been doing this for years, without apparent ill effects.
    Excessive time in direct sun, may change final colour finish. How much is not known.
    Drying time, is only required long enough to allow baking that will result in good product and passes tests. If your coated cast gets to about 40-50C, it should be adequate for baking.
    The coating advice is, to test bake a few at intervals, to determine if coating is dry enough. If test baking a few, and they pass baking and other tests, the rest should also be ready to bake.
    I dont really think that having product sitting in sun at 60C for hours is a good idea.

  9. #14329
    Boolit Master
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    I got mixed up on what you were referring to, my fault.

    In hot weather I put the coated bullets out in the full sun and go and do something else for a few hours. I know hey are ready to bake in 30 min or less so I will bring them back in the shop after 30 min and not hours.

    Thanks for the reply.

  10. #14330
    Quote Originally Posted by popper View Post
    Jatz would be interesting to find the absorption/transmission cure bands of the HiTek. H2O basically has none so drying would be from normal conductive heating from the HiTek coating/alloy temp. Elec. elements work fine but the 'window' needs to be quartz as window glass doesn't transmit long IR very well. Evidently IR cooking is THE way for PC/HiTek commercial cooking. The high specific heat/conductivity of lead is what takes the time in oven.
    Basically appears that IR heats the lead which then melts and cures the coating. So the cure is from the inside to outside as you thought. Like the UV cured stuff, IR cured would be neat as it takes MUCH less energy. HiTek says the chems for UV curing are too expensive for bullet coating.
    Popper,

    There is still much to do in the way of testing Hi-Tek with infrared curing.

    I don't use nor recommend halogen infrared as it may be too intense on the surface and will possibly burn the coating before it heats the lead to cure temp. (halogen, good for pizza ovens or T-shirt dryers) and cause trapped moisture to turn into superheated steam and cause loss of coating bond to the lead surface.

    The key seems to be the time it takes for the substrate (lead) gets to cure temperature.

    With well dried Hi-Tek I have been able to cure small batches of projectiles in around 3 minutes 20 seconds and less. These tests were without any temperature control and the temp far exceeded what is required to cure Hi-Tek. The coating still bonded to the lead and the only issue was the colour went a little darker.

    I have not completed any high temp fast cure tests with coating that has only being drying for a short time.

    Several tests have now been completed where a batch of projectiles have been coated when the ambient temperature has been low 10 to 12 degrees. Once coated the projectiles chilled by 4 or 5 degrees.

    They were left to dry for about 90 minutes and then placed on the infrared oven conveyor without any pre-heating, projectile temp before entering the oven was around 10 degrees. They ran through the oven as per my normal temperature and time settings.

    Projectiles past the smash and wipe tests.

    2nd coat was applied and allowed only 20 minutes dying time with no force dry or pre-heating. 2nd bake smash and wipe tests passed.

    Another test has been completed where drying time was about 60 minutes and the projectiles were left outside to dry in the late afternoon as the temperature was dropping fast in the shade. These were then baked as per normal settings and passed smash and wipe tests.

    Next test to be completed will be with very limited dry time 10 - 15 minutes in cold conditions and then bake and see what happens.

    I suspect that such a short dry time may be pushing the limits however, results in my opinion, will depend on relative humidity, dew point and temperature of the projectiles before they enter the oven.

    Should short dry time, high humidity and high dew point cause bonding failure (failed smash test) the next step would be to reduce the oven stage one temperature and increase the baking time. In short, slow the time taken for the substrate (lead) to reach cure temp. This will allow more time for any moisture to evaporate before the coating starts to cure.

    Currently I'm curing Hi-Tek at a rate less the 5 minutes 30 seconds. Even increasing the time by another minute will still outweigh longer pre-dry times and especially pre-heating the projectiles.

    Don't forget, Hi-Tek is actually simple to use. It's people like Auglock, myself and many others that have conducted numerous tests and experiments to help us understand how to achieve the best results with conventional and infrared.

    UV curing is another league. I have no experience with UV curing other than I understand it's a very quick cure process. Any oven or curing device would need to allow UV to penetrate the complete surface of the projectile and, that creates a whole new problem.

    More details about my infrared will be available once a commercial design has been released.

  11. #14331
    Boolit Mold
    Join Date
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    Jatz sent you a pm


    Quote Originally Posted by Jatz357 View Post
    Popper,

    There is still much to do in the way of testing Hi-Tek with infrared curing.

    I don't use nor recommend halogen infrared as it may be too intense on the surface and will possibly burn the coating before it heats the lead to cure temp. (halogen, good for pizza ovens or T-shirt dryers) and cause trapped moisture to turn into superheated steam and cause loss of coating bond to the lead surface.

    The key seems to be the time it takes for the substrate (lead) gets to cure temperature.

    With well dried Hi-Tek I have been able to cure small batches of projectiles in around 3 minutes 20 seconds and less. These tests were without any temperature control and the temp far exceeded what is required to cure Hi-Tek. The coating still bonded to the lead and the only issue was the colour went a little darker.

    I have not completed any high temp fast cure tests with coating that has only being drying for a short time.

    Several tests have now been completed where a batch of projectiles have been coated when the ambient temperature has been low 10 to 12 degrees. Once coated the projectiles chilled by 4 or 5 degrees.

    They were left to dry for about 90 minutes and then placed on the infrared oven conveyor without any pre-heating, projectile temp before entering the oven was around 10 degrees. They ran through the oven as per my normal temperature and time settings.

    Projectiles past the smash and wipe tests.

    2nd coat was applied and allowed only 20 minutes dying time with no force dry or pre-heating. 2nd bake smash and wipe tests passed.

    Another test has been completed where drying time was about 60 minutes and the projectiles were left outside to dry in the late afternoon as the temperature was dropping fast in the shade. These were then baked as per normal settings and passed smash and wipe tests.

    Next test to be completed will be with very limited dry time 10 - 15 minutes in cold conditions and then bake and see what happens.

    I suspect that such a short dry time may be pushing the limits however, results in my opinion, will depend on relative humidity, dew point and temperature of the projectiles before they enter the oven.

    Should short dry time, high humidity and high dew point cause bonding failure (failed smash test) the next step would be to reduce the oven stage one temperature and increase the baking time. In short, slow the time taken for the substrate (lead) to reach cure temp. This will allow more time for any moisture to evaporate before the coating starts to cure.

    Currently I'm curing Hi-Tek at a rate less the 5 minutes 30 seconds. Even increasing the time by another minute will still outweigh longer pre-dry times and especially pre-heating the projectiles.

    Don't forget, Hi-Tek is actually simple to use. It's people like Auglock, myself and many others that have conducted numerous tests and experiments to help us understand how to achieve the best results with conventional and infrared.

    UV curing is another league. I have no experience with UV curing other than I understand it's a very quick cure process. Any oven or curing device would need to allow UV to penetrate the complete surface of the projectile and, that creates a whole new problem.

    More details about my infrared will be available once a commercial design has been released.

  12. #14332
    Quote Originally Posted by m37 View Post
    Jatz sent you a pm
    M37, have now replied.

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