simple Hi-Tek coating

[Ausglock]

Mate....Not trying to be rude, But go read the HITEK do's and don'ts thread.
Everything you need to know is in there. It has been done to death.

[Avenger442]

Thank you Trevor. I had forgot about that. It's only 8 pages rather than 454. Every time we have a new user we need to send them there.

[benellinut]

HI-TEK do's and don'ts---> http://castboolits.gunloads.com/show...o-s-and-don-ts

[kevin c]

Update on my post #8980

Short version: HiTek working great with the new oven.

Longer version: I was getting a bit of wipe off with the Black Cherry mixed 20 grams measured to 120 ml acetone measured, well mixed, 6 ml coat to 5# casts, dried overnight and then baked with a cheap convection oven at a K probe measured 200 to 205 C even at 18 to 20 minutes.

The new Breville moves air better: less than 5 C variation in temp between 1" over and 1" under the tray, versus up to 20 C variation in the old oven. Temp recovery on opening the door was faster too (no heat holding thermal masses used). Dial temp only low by 5 C, and little fluctuation.

At first I still got wipe off at 16 to 18 minutes, but then realized my test technique of putting several coated bullets in with a full load of uncoated bullets (to save me the hassle of melting a whole batch of incorrect bakes) and pulling them out a pair at a time at two minute intervals to test for adequate polymerization was flawed - the oven temp would drop below threshold and would stiil be recovering the next time I opened the door, so all the bullets ended up with bake times that really did not vary much from start at 8 minutes to the end at 20 minutes.

Fiddling eventually got me to a K probe temp of 210 C over 14 minutes. The bullets come out with just the right Black Cherry color as posted here, now zero wipe off and no flaking on the smash test, and nothing in Glock factory bores except what brushes out easily with a dry phosphor bronze brusH (I'd gotten the latter results the very first time I coated, but only with the extra long bakes, which are consigned to the trash, as was the old oven).

Color me highly satisfied.

[Avenger442]

Works for me.

[dansedgli]

I'm having a shambles of a week for coating. My own fault for not being patient.

3000 bullets need to be melted down as I'm having the coating scrape off when sizing. I have been using 100ml of acetone with 20g of powder. Mixing 1ml to 1 lb of bullets.

Can acetone go off? I am using a bottle I bought last year. Stored in the same bottle but I did use some of it last year.

With the suggestions above of my coating not being completely dry I coated and left them overnight in my garage before baking. Could the cold night air affect the coats? I was doing some loading one night this week and my gun had moisture on it from sitting on the bench for a few hours. It's maybe gotten down to 4 or 5 degrees celsius down here in melbourne.

[Ausglock]

Dan. pinch the old girls hair dryer and warm them to just above room temp.
Or. place the tray ontop of the oven while it is heating up.
This will dry the coating and you will be good to go.
Sure you don't want me to send you a care package????

[dansedgli]

Thanks Trev but I'm hoping to have my own bullets sorted before I finish off these short fat tigersharks that don't feed in my gun.

I'll cast some more tomorrow and try warming them up first. It has to that or the acetone. I'm fairly sure I'm doing everything else the same as last year when it was working for me. It might have been warmer this time last year.

[Lakehouse2012]

Might also try taking a 100 of the bad ones just like they are and put in the oven again at a higher temp. Its not a problem to double bake.

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[HI-TEK]

Might also try taking a 100 of the bad ones just like they are and put in the oven again at a higher temp. Its not a problem to double bake.

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Trying to re cook is not going to fix problems of adhesion.
Once Hi-Tek coating is subjected to heat in an oven, with a second cook, it cannot be made to bond to the alloy if it did not bond the first time.
The coating has set with first cook. I am afraid that it is a re-melt job.
Drying well before cooking is only cure.
I have always tried to advise, to first, simply cook a few to test dryness.
If they fail, then dry the rest longer or continue to warm dry. Then re-test with only a few until they pass.
Just thinking that they are dry, especially in cool conditions and not testing first, will result in such problems.
Sorry.

[popper]

Joe, seems like toluene is the least hydroscopic of the solvents. Does it work well with HiTek? From my testing it is the water in the solvent that is the problem as well as the 'skinning' of the HiTek as it dries (holds moisture in). This begs the question of running @ 100C to cook the h2o out, then increasing to 200C for the bake. thoughts?
It appears that silica gel with cobalt added is good for drying solvents. The kind that changes from blue to pink when 'wet'. Used to dry lab chemicals. It appears that h2o has H bonds with the acetone so it's not just a mixture. Heat can break the bonds.

[Grmps]

A good fan really helps with the drying

[dansedgli]

Thanks guys.

I did more reading last night and found that dry to the touch doesnt always mean they are dry enough. This must be where ive gone wrong with the weather we've been having.

[Ausglock]

Dan. You got a fan/heater? $15 at Bunnings. sit the tray in front of it for 5 minutes to warm them up.
You need to move up here to the warmer climate, mate.
Get out of Mexico.

[dansedgli]

Ill go pick one up tomorrow.

[HI-TEK]

Joe, seems like toluene is the least hydroscopic of the solvents. Does it work well with HiTek? From my testing it is the water in the solvent that is the problem as well as the 'skinning' of the HiTek as it dries (holds moisture in). This begs the question of running @ 100C to cook the h2o out, then increasing to 200C for the bake. thoughts?
It appears that silica gel with cobalt added is good for drying solvents. The kind that changes from blue to pink when 'wet'. Used to dry lab chemicals. It appears that h2o has H bonds with the acetone so it's not just a mixture. Heat can break the bonds.

Thanks much Popper.
Unfortunately, solvent like Toluol are not suitable, as solvents are required to be "Polar" in nature.
Acetone was chosen, mainly for quick drying time, high solubilising characteristics, and reasonably lower toxicity as compared with Aromatic type solvents.
Acetone will pick up moisture quickly and if coating is applied too thickly, that absorbed moisture is trapped inside the coating during drying.
After coating, the evaporation of Acetone "chills" the alloy by up to 5C. This makes things worse as cold surfaces attract moisture.
Also, main issues, that seem to be causing the problem, is the idea that coating is required to go on thickly.
This causes the skinning and water entrapment, and coupled with cold damp weather, drying issues.
Pre-warming alloy prior to quick coating, or as Ausglock said, warm air drying normally fixes problems.
Other failure causes are, people thinking that a more concentrated coating mix, and using more than required to coat is what is required.
This idea is totally wrong.
Whatever the reason, and despite many write up advice against such procedures, people try to adopt other methods and then wonder what has gone wrong, (and of course, it is the coating that has failed)
One thin, well dried and baked coating will work in majority of cases, but it looks awful.
I hope this helps.
HI-TEK

[dikman]

Yep, swap the cold and damp for the heat and damp (as in high humidity).

Here in the Adelaide Hills it can also get cold and damp, but if the weather's a bit on the unco-operative side I warm the oven a bit and stick the trays in there for a while to make sure they've dried. I also only do a couple hundred or so at a time, might not be the most efficient way of doing them but if something goes wrong it's less to re-do. Mind you, I haven't had to re-do any since my first batch.

Having to melt down 3,000 - .

[Lakehouse2012]

Thanks much Popper.
Unfortunately, solvent like Toluol are not suitable, as solvents are required to be "Polar" in nature.
Acetone was chosen, mainly for quick drying time, high solubilising characteristics, and reasonably lower toxicity as compared with Aromatic type solvents.
Acetone will pick up moisture quickly and if coating is applied too thickly, that absorbed moisture is trapped inside the coating during drying.
After coating, the evaporation of Acetone "chills" the alloy by up to 5C. This makes things worse as cold surfaces attract moisture.
Also, main issues, that seem to be causing the problem, is the idea that coating is required to go on thickly.
This causes the skinning and water entrapment, and coupled with cold damp weather, drying issues.
Pre-warming alloy prior to quick coating, or as Ausglock said, warm air drying normally fixes problems.
Other failure causes are, people thinking that a more concentrated coating mix, and using more than required to coat is what is required.
This idea is totally wrong.
Whatever the reason, and despite many write up advice against such procedures, people try to adopt other methods and then wonder what has gone wrong, (and of course, it is the coating that has failed)
One thin, well dried and baked coating will work in majority of cases, but it looks awful.
I hope this helps.
HI-TEK

That is a fascinating response Joe! I have been following directions with good results but have on occasion thinned the mix with more acetone then directed and now i understand why my results have been acceptable.

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[Avenger442]

We have had this discussion before on this thread. But it is important to repeat things. Different climate conditions will affect the drying and there may be a need to adjust. We compensate with fans, heaters, or both. One guy on here mentioned putting them over the condensing unit fan on his air conditioning unit.

A thin coat, a stain as some have called it, for the first coat dried in my basement overnight always works for me. After that first coat is stuck well the next two are a breeze. My basement has a dehumidifier going in the spring, summer and early fall when the humidity is up. Not unusual here to see 80-90%+ humidity. It has a heat source in the fall and winter. Here the saying is "if you don't like the weather today don't worry it will change tomorrow". Right now we are having heavy rain. And tornados are going by the county I live in on both sides. Remains of the hurricane that hit Texas are in Alabama. Hope Donnie made it through OK. It hit Louisiana a little harder.

Went to Arizona once. It is so dry there that it must be the perfect place to dry your bullets. Any of you guys live in Arizona?

Still having excellent results at the range with Hi Tek my rifles and handguns. I have about 150 rounds down the barrel of my .308 since real cleaning and most of the accuracy is still there as far as I can tell. Just one dry patch before each range trip. The .357 has over 200 since cleaning. I think the Hi Tek lets you shoot longer between cleaning. Another plus.

[dansedgli]

Casted up 500 bullets on my lunch break. Keen to try again tonight. Plus im running out of ammo.