simple Hi-Tek coating

[HI-TEK]

Ok, now here's a connundrum....

I'm a commercial ammunition manufacturer. (I'm also a serial lurker in this thread) Typically we load either J-word of electroplated CMJ bullets that we source from a manufacturer locally. We have bought in a reasonable quantity of Joe's Hi Tek powder some time ago to coat some of our own castings in more obscure calibers that dont require high volumes, and went through the whole learning curve. We coat using foundry lead (92-8), commercial acetone, and a commercial convection oven.
(Please bear with the long post, I'm trying to give enough detail to limit questions later)
Our initial attempts worked OK- for personal use- but the resultant product, although passing all the tests perfectly, smoked a bit more than CMJs and left a chemical smell in the air after firing. I stopped fiddling with it and carried on shipping in the plated bullets. Late last year, I followed the adventures of Petander here and his acid wash and decided to revisit Hi Tek.

Cast bullets were soaked overnight in undiluted swimming pool HC acid, and boy did they react- foul smoke coming out of a boiling bucket! The resulting bullets were a dark powdery grey that needed scrubbing to remove the powdery residue on them. I then got one of my staff members, who had previously been doing the shaking and baking to coat and bake them for me and we loaded up a batch (testing smash and wipe 100%) that were coated 2x (124gr 9mmP) and took them to test. these bullets were perfect, they shot accurately, the recoil felt softer than normal, but velocities were about 50fps faster than the plated bullets with the same loads, and there was no undue smoking. Best of all, the chemical smell had dissipated. There was no leading at all either. The reason for using 124 gr 9mmP was to test a higher pressure bullet than a 38 or a 45.
Ok, so whats the problem you may ask?
We have been casting and loading coated bullets for the last two months with no issues. The local market has been slow to adopt them over the more traditional CMJs as range ammo, but we have now developed a nice following. Last week I checked on the process my staff are following, and found that the idiot here has been baking the two coats at 110 degrees centigrade for 10 minutes instead of at 200 C. He has done two months of production like that. Everything I have read here says that there is no way that the coating would have worked like that, but- and I took 1000 rounds of 124gr 9mmP to the range this weekend and shot them through 3 different 9mmP firearms, including a MP5 with a new, tight and longer barrel- I had the same good results as earlier. All these 'poorly' coated bullets more than exceed the two tests, and its near impossible to get the coating to come off, even when hammered thin multiple times. There was no leading in any of the firearms, accuracy was superb, the smell and smoke issues are still solved... colour me stupid, but everything written here by smarter people than me tells me that this should not be the case?
I'm not a chemist by any means, but the acid wash step has really worked for us- the foundry lead we get here is all recycled lead, and still has traces of other unwanted elements in it- the acid sorts that out and leaves a pockmarked surface that implies a great coating surface.( Thanks Petander, for the clue to solving the problem!) It may be that traces of the acid have helped the adhesion (??) and made up for the mistakes of my staff member- I dont know. Its a mystery to me. Future bakes will be done as per the instructions, but- and I dont know why- what should have been a horrible failure has tested to work as if it had been done in accordance to the instructions. the only additional step we have put in the process is the acid wash (Which, unlike Petander's wash, uses undiluted acid for 18 hours) In addition, about a hundred thousand of these 'mistakes' have been shot by satisfied customers this year already, with no complaints and nothing but compliments.
Amazing stuff, this Hi Tek!

Hello SAndy37

WOW...…. You have got me stumped. All I can say is that at 110C this coating should not work/cure or cross link.
The design of the coating, is to cross link, and cure with internal materials that react, starting slowly at temperatures beginning at about 150C, and is most efficient and complete results with cross linking occurring around 180C and onwards.
The 200C oven heat simply supplies heat, to quickly get load up to best cure temperatures producing fast production rates for commercial casters..
If your acid wash reacts so violently, I assume that your alloy has a lot of contamination, and I am 90% plus sure that this also interfered with coating cross linking properly, and completely, at 200C and therefore caused the odours you experienced, as polymer could not cross link adequately with the interference caused by contaminants present in the alloy..
I think, that you may have also discovered that acid residue on alloy, may assist with the cross linking, but I am at a loss why that would occur and at such low temperatures. This simply should not happen, but it seems that it did.
Another thought is, that metal salts produced with acid pickling may also contributed to accelerated cross linking. This is only a guess as I don't really know.

I really appreciate your detailed report, and am glad that all is working, but as I said, according to all heat cured done over years, where low heat was applied, (on 92:6:2 alloy) the coating simply did not work as designed at lower temperatures.
You have just thrown out all that history and achieved something that I had never expected nor designed into the polymer..
All I can say well done, but with caution..
Just curious, can you send or post pictures of 110C baked ones and the 200C ones when available.
Thanks much
Joe

[SAndy37]

Thanks Joe

I also am stumped as I have followed numerous failures here due to incorrect heating, even by much smaller margins of error. I intend however to continue at the correct 200C temp in future. My post is not intended to imply that users should disregard the instructions in any way- this seems to be an outlier case and may have something to do with the acid we used- its swimming pool acid from the local hardware store and I suspect that it may not be as pure as advertised- perhaps there is a chemical hiding in there that caused this? The contamination issues with our supposed foundry lead are extreme it seems, but the acid did resolve them- for the record, we cant get 92:6:2 alloy here and use 92 lead:8 Antimony as a substitute. I have little success with posting pictures here. I will however email them to you.

[HI-TEK]

Thanks Joe

I also am stumped as I have followed numerous failures here due to incorrect heating, even by much smaller margins of error. I intend however to continue at the correct 200C temp in future. My post is not intended to imply that users should disregard the instructions in any way- this seems to be an outlier case and may have something to do with the acid we used- its swimming pool acid from the local hardware store and I suspect that it may not be as pure as advertised- perhaps there is a chemical hiding in there that caused this? The contamination issues with our supposed foundry lead are extreme it seems, but the acid did resolve them- for the record, we cant get 92:6:2 alloy here and use 92 lead:8 Antimony as a substitute. I have little success with posting pictures here. I will however email them to you.

SAndy37
As I tried to explain, before acid treatment, at correct baking temperatures (200C), the coating was damaged directly attributable to contaminants in the alloy.
After Acid treatment, which removed contaminants, coating worked OK.
The peculiarity is, that coating cured at wrong (Low) temperature conditions after acid treatment.
The curing at low temperatures, could be due to residual acid or acidic salts from pickling or both.
I really don't know, but what you found has me thinking that way.

[Petander]

I'm glad to hear that my HCL adventures have helped.

That low temp cure sounds really odd though.

But HCL soaked bullets are very easy to coat and bake. I haven't used a thermometer for months and I bake a few 5-10 pound batches every week. My outside shed (where the baking oven is,I dry bullets inside) temp varies -20°C to +10C°, it's going good without adjusting anything except time,depending on bullet size/shape. My oven dial says 200 C°,that's it. I can tell by my nose when they are ripe,I don't overbake anymore.

[Avenger442]

Joe
Can you use muriatic/hydrochloric acid to dip the bullets? Will it interfere with the coating? I have some that we dilute to clean masonry and concrete.

SAndy37
I'm with Joe. That curing at 110C is a mystery. I tried curing at lower temps and times as an experiment early on while working on some colors. Anything under 180C for 10 min. in my oven gave me a wipe failure.

Imagine you sell a lot more handgun bullets than rifle, if you sell any rifle bullets. But if you have the time try the Hi Tek in a rifle. Higher pressure and longer time in the barrel than the 9mm. I've used it in .223, .308, 45-70. It seems to give the same speed with a slight reduction in powder load over jacketed. My 41.5 grains of H4895 with a 168 grain lead .308 bullet with gas check coated three times is giving me very good accuracy with no leading in my gun. Speeds are around 2600 fps. Lead is between 12-14 BHN. In handgun I have used Hi Tek in .357 magnum, .380, .38 special, .44 magnum, and .45 auto. The last tested .380 gave same size groups as Hornady Critical Defense loads with less recoil. All with good accuracy and no leading. BHN on some of those leads were around 10. The magnum loads were middle of the road and shot without gas checks. Still learning how to do this handloading casting stuff but I think you can get any accuracy you want with Hi Tek.

I did, accidentally, shoot some 44 mag Hi Tek coated with a load that made my hand sore. Disassembled all but three of the rounds. Somehow the Hornady progressive dropped a little too much Titegroup? I hand weigh Titegroup now. But still no lead in the barrel of the Ruger.

I too have trouble uploading photos. Have photos of targets and some other stuff that I can't put up. Going to have to work on this photo posting thing again. I may have posted too many and need to remove some in my past post since I post from my computer to this forum.

[Petander]

HCL=Hydrochloric Acid=Muriatic Acid=Concrete Wash. All the same.

Concrete wash is usually about 30%. There are different products being marketed as "Concrete wash", too.

[Avenger442]

Thanks Petander

I don't have any contaminated lead right now. But it is good to know that if I were to have that problem I can use the muriatic acid on the cast bullets. Also have been conversing with a guy using Hi Tek that may be having a problem with contamination in his lead. So this might be a solution for him.

I have used copper sulfate in stump remover to remove zinc that was intentionally added to the lead. Did this to add copper to the lead. Those bullets coated and shot well. Benefit of the copper was to make bullets tougher/harder without being brittle. The process was not something I would want to do again. But it is another thing added into the library of things that can be done to fix a problem like the muriatic acid.

[HI-TEK]

Joe
Can you use muriatic/hydrochloric acid to dip the bullets? Will it interfere with the coating? I have some that we dilute to clean masonry and concrete.

SAndy37
I'm with Joe. That curing at 110C is a mystery. I tried curing at lower temps and times as an experiment early on while working on some colors. Anything under 180C for 10 min. in my oven gave me a wipe failure.

Imagine you sell a lot more handgun bullets than rifle, if you sell any rifle bullets. But if you have the time try the Hi Tek in a rifle. Higher pressure and longer time in the barrel than the 9mm. I've used it in .223, .308, 45-70. It seems to give the same speed with a slight reduction in powder load over jacketed. My 41.5 grains of H4895 with a 168 grain lead .308 bullet with gas check coated three times is giving me very good accuracy with no leading in my gun. Speeds are around 2600 fps. Lead is between 12-14 BHN. In handgun I have used Hi Tek in .357 magnum, .380, .38 special, .44 magnum, and .45 auto. The last tested .380 gave same size groups as Hornady Critical Defense loads with less recoil. All with good accuracy and no leading. BHN on some of those leads were around 10. The magnum loads were middle of the road and shot without gas checks. Still learning how to do this handloading casting stuff but I think you can get any accuracy you want with Hi Tek.

I did, accidentally, shoot some 44 mag Hi Tek coated with a load that made my hand sore. Disassembled all but three of the rounds. Somehow the Hornady progressive dropped a little too much Titegroup? I hand weigh Titegroup now. But still no lead in the barrel of the Ruger.

I too have trouble uploading photos. Have photos of targets and some other stuff that I can't put up. Going to have to work on this photo posting thing again. I may have posted too many and need to remove some in my past post since I post from my computer to this forum.

Avenger
Aside from SAndy37's report I have no idea what affects any Acid will cause to the coating.
It seems, that SAndy37 found that he can cure coating at about 110C.
That is unheard of previously and theoretically should not be possible..
As I said, the only rationale explanation is, that there was residual acid on the metal, possibly combined with acidic metal salts, and somehow this may have resulted in better bonding, but allowed fast cure at lower temperatures.
I would not recommend such activity, and I have no explanation why this happened, only a guess at this stage.
The bonding improvement may have simply been caused by a huge increase in surface area after acid pickling was done.

[Tazza]

A guy at my range said he cures at stupidly low temperatures too, like 100c, he said it was Hi-Tek, but i'm not so sure it actually is or not. Hi-Tek needs the higher temperatures to do it's linking, as did my old coating, if it's not hot enough for long enough, they fail wipe tests, a re-bake fixes it though.

The etched surface would give a great bond too, like anodizing aluminium, giving all these little pores for the coating to get into and grip onto.

[HI-TEK]

A guy at my range said he cures at stupidly low temperatures too, like 100c, he said it was Hi-Tek, but i'm not so sure it actually is or not. Hi-Tek needs the higher temperatures to do it's linking, as did my old coating, if it's not hot enough for long enough, they fail wipe tests, a re-bake fixes it though.

The etched surface would give a great bond too, like anodizing aluminium, giving all these little pores for the coating to get into and grip onto.

Tazza, You are correct. As Petander found, removing impurities from surface of cast contaminated Lead, leaves a porous surface which is ideal for Hi-Tek coatings.
Aluminium Anodizing is similar but different. Aluminium has an Oxide layer which quickly forms on clean metal. The Anodizing removes Oxide layer, and leaves a porous surface but also leaves a Phosphate coating which also provides large surface area. Aluminium is a very reactive metal, and with Hi-Tek coatings, there is a reaction with the metal itself which interferes with bonding and curing. It is possible that after Anodizing, the Hi-Tek coatings may bond to Aluminium, but I have not done work in this area, as that was not the purpose or design of the coatings initially.

I am amazed that people will try shooting inadequately cured coatings. Not adequately cured Hi-Tek will react with heat from powder burn and bond inside gun bore. Then user will have a great time, trying to remove bonded coating from the bore, as it will no longer dissolve in most solvents or cleaners.

[Avenger442]

That is one of the first things I thought of with the 110 C cure. I wonder if any of the coating came off inside the barrel. That has happened and been discussed on this thread. I might use some bullets that slightly don't pass a smash test. Would put up photos but.... But I'm not going to use a bullet that really fails a wipe test.

[Conditor22]

Curing is also important in PC, many don't understand that. if the polyester isn't completely cured it can be affected by several types of smokeless powder.
The coating becomes tacky and the powder sticks to it. Is this true with HiTek also?

Playing around with PC, does this look like Kryptonite?
top is PC


HiTek Kryptonite Bottom is HiTek Kryptonite

[Avenger442]

On the loads that I have disassembled I have never found the coating to be tacky with Hi Tek. But mine are usually wipe tested to make sure they are cured. The only time I don't do this is when I over bake on purpose.

It was my understanding from a couple of PC buddies that certain powders will make the base of the bullet tacky even if cured. Don't remember the type powder. And I might be wrong. I'm going from my memory of those conversations. The only PC rounds I have shot were coated by someone else. I don't use it to coat myself. Those PC would have been shot right after loading since I was doing some testing. I have never disassembled a PC that has been stored for a while which is what I remember the problem being with the tacky base.

[HI-TEK]

Curing is also important in PC, many don't understand that. if the polyester isn't completely cured it can be affected by several types of smokeless powder.
The coating becomes tacky and the powder sticks to it. Is this true with HiTek also?

Playing around with PC, does this look like Kryptonite?


HiTek Kryptonite

Conditor22
The colour is more like Zombie Green. Is that Powder coating or Hi-Tek powder?

[SAndy37]

Avenger, the bores of all 3 weapons were clean, a single wipe through with a solvent mop to remove powder residue and they were spotless.
The 'mistake' bullets passed both smash and wipe tests.
As I mentioned in my earlier post, I'm not encouraging anyone to try this, and we have already gone back to 200 C baking for 10 minutes- 2 coats. the entire thing is a mystery to me and I mention it here only for completeness. I have however the utmost faith in the acid wash process if using contaminated or suspected contaminated lead- its an additional messy and probably pretty hazardous step but leaves a surface that can only improve bonding. To the point that if I was offered uncontaminated lead now, I'd probably stick with the contaminated stuff and live with the toxic fumes and acid splash risk.

[HI-TEK]

Avenger, the bores of all 3 weapons were clean, a single wipe through with a solvent mop to remove powder residue and they were spotless.
The 'mistake' bullets passed both smash and wipe tests.
As I mentioned in my earlier post, I'm not encouraging anyone to try this, and we have already gone back to 200 C baking for 10 minutes- 2 coats. the entire thing is a mystery to me and I mention it here only for completeness. I have however the utmost faith in the acid wash process if using contaminated or suspected contaminated lead- its an additional messy and probably pretty hazardous step but leaves a surface that can only improve bonding. To the point that if I was offered uncontaminated lead now, I'd probably stick with the contaminated stuff and live with the toxic fumes and acid splash risk.

My suggestion is to dilute acid before using, and add 1 litre of Acid to 2 litres of water.
Using strong acid is not beneficial at all. Because you soak over night there is no problem.
Just a note, do this outside. Metals dissolving in acid produce flammable gas and must be avoided to getting accumulating in closed areas.
Always use suitable gloves, goggles, and impervious apron, and have running water near you to rinse/wash off accidental contact.
Spills can be easily dealt with by using Bicarb Soda mixed into water kept near by where you are working. This is a very safe and easy to use neutraliser, which instantly neutralises the acid. Have plenty of bicarb water handy, and it does not go off. Mix about 2-3 pounds bicarb in 5 gallons of water.

[Burnt Fingers]

Tite-Boom aka Tite-Group will stick to PC even if it's properly cured.

I've never had a problem with H-Tek sticking.

[Avenger442]

I've had problems with Titegroup and the Hornady dispenser on my progressive press with other calibers. But none of them were as dramatic as the .44 mag. The third round actually jammed the cylinder on the Ruger. I think it has something to do with the small number of grains between min. and max. loads. Loads need to be precise. With most powders I use, a couple of tenths off and it doesn't make a lot of difference. So, like I said, I hand weigh all Titegroup loads now. This powder works great for short barreled carry guns. It is indeed a "Tite Boom".

I've got a new mold HTC310-247-FN-BO3 RG4 cavity PB. Because of the weight (hollow point cast 230 grains) I had to go back to a 1989 loading manual to find loads for it and a .308. It may eventually go into the .30-06. I was concerned about the COL but over half this bullet length, diameter .299, extends past the beginning of the lands. It's a tail rider. Odd casting. Interested to see what it will do. May not stabilize in my barrels. Going to coat with Hi Tek of course. Already have some cast and some 1035 Gold made up. Will start with min to mid loads.

[Petander]

My suggestion is to dilute acid before using, and add 1 litre of Acid to 2 litres of water.
Using strong acid is not beneficial at all. Because you soak over night there is no problem.
Just a note, do this outside. Metals dissolving in acid produce flammable gas and must be avoided to getting accumulating in closed areas.
Always use suitable gloves, goggles, and impervious apron, and have running water near you to rinse/wash off accidental contact.
Spills can be easily dealt with by using Bicarb Soda mixed into water kept near by where you are working. This is a very safe and easy to use neutraliser, which instantly neutralises the acid. Have plenty of bicarb water handy, and it does not go off. Mix about 2-3 pounds bicarb in 5 gallons of water.

I use 30%. It can be used 2-3 times,just takes longer each time to make the bullets dark.

I tried soda in final wash after soak but I don't use it anymore. I also wash less carefully than before, some dark stains don't seem to matter with coating at all. The dark stuff that comes off and stays on the bullets actually mixes with coating,making it darker. But the coating quality is excellent.

I dry my bullets in the oven before coating,they hit 150°C at least.

My contaminant is Niobium,it must have come from monotype that I mixed with WW many years ago when I made a ton of 20 pound ingots one summer. Hi Tek really got me back into casting!

[Tazza]

I have tinkered with attempting to recover gold and silver from old computer scrap, the research i have done on the internet has pointed out that to dissolve base metals, you actually want dilute acid.

When the metal is being dissolved, it needs somewhere to go, it doesn't just evaporate, if the acid is really concentrated, there is less water for it to go into solution than a dilute mix. I'm sure Joe will set me straight on this if i'm wrong.