simple Hi-Tek coating

[dansedgli]

That website says nothing about the coating being absolutely 100% dry enough which was the cause of my problems when I was getting flaking.

The hitek can be dry to touch but still not dry on the bullet side of the coating which means it doesnt bond.

[HI-TEK]

[QUOTE=Petander;4353007]How I wish I had some good and bad HT boolits on hand.

It's hard to chase The Perfect HT Boolit if you've never held and smashed one. I tend to get flaking on the second coat now, here I did three identical bakes on and the golden ones flake very little,the other two colors are worse.

How much flaking is too much? The first bake is perfect, an identical second bake starts flaking when smashed. I once baked the first coat alone for a second time and yes,it started flaking.

Attachment 218991

About overcooking...

Attached is over cooked coatings.
The coatings should not flake with over baking.
As per pictures, baking at 200C for extended time, all passed test and shot well and accurately.
No Leading.
The coating and alloy must reach at least 180C, then be held there or above for another 3 minutes for a more complete cure.
Larger sized flakes with a second coat are generally caused by not enough drying, and also not being baked at correct conditions long enough possibly a combination of both..
The Plain colours allow slightly faster heat transfer into the alloy, and the "Metallics" reflect heat more, and it can be possible that alloy/coating did not heat up and cure adequately.
After applying second coat to a good first coat, (making sure that coating is dry) simply cook only a few for say 3-4 minutes longer, and compare results. Colours may darken, but coating should be OK.

Over Cooked

Refer to below link to see over cooked coating results.
Over Cooked coating.pdf

[Ausglock]

Fired around 400 rounds through the STI yesterday.
A real mixture of weights, shapes and colours.
The gun is still in the "run in" stage.
There were, KG. red copper, bronze 500, Red 122k, Red 254, Brick red, Gold 1035, CandyApple, Gunmetal and Black K15.

Got home and again, 1 patch wet with hoppes down the bore and it is shiny clean. Mirror bright.
These were a mix of different propellant powders as well. Win 231, AP-50, AP-70, AP-90, Power pistol, WST, Unique, Win 540 and green dot.

All worked fine.

This STI eats everything I throw at it from SWC to RNFP.
Most impressed with it.

[Ausglock]

Are you using any sort of mold release when casting?

No contaminants on your bullet storage containers.
Thanks, But I'll keep this STI...

[HI-TEK]

[QUOTE=Petander;4353224]Attachment 219017

Gold was the best of the bunch. I have read the thread and tried longer cure times up to color change. Smash fail at 15 minutes,wipe fail at 10 minutes. I also have left some boolits in the oven bottom for days.


If you have solvent test failure after 10 minutes, the coating and alloy has not baked at correct conditions for long enough or you may have a contamination which prevents cross linking.

The solvent test is to specifically determine, if polymer is cross linked/baked adequately. If baking is inadequate, next coat application will simply strip off previous coat.
The important thing is that first coat passes both smash test and solvent test before you again coat.
If either fails, or both, with first coat, and after baking, you really have to examine why.
If you baked first coat, you cannot repair poorly bonded first coat by applying a second coat.
You have to find out why first coat failed any test. Change one parameter each time and test changed result.

Silly questions
1. How much alloy are you baking each time?
2. Are you measuring alloy load temperature or oven temperature?
3. What solvent are you using to make up coating mixture?

I am concerned, that after 10 minutes you get solvent wipe test failures and you are obtaining smash failures after 15 minutes.
That is not normal results.
The coating as posted recently, will not fail smash test after extended cooking. The colour should darken but no flaking. Flaking off is mainly due to inadequate drying or contamination, which results in coating being prevented from bonding.

[HI-TEK]

[QUOTE=Petander;4353236]

Silly answers: I have tried everything from six to 20 minutes bake. Many different temps. I measure everything everywhere. I have so many notes it's overwhelming now.
Please simply do a single coat, and dry. When you think they are dry, cook only a few. Do not worry about colour. Cool and do tests. Both tests have to pass. If it fails tests, continue drying for longer, and repeat test baking only with a few, with all setting and time being same as first test. If second small batch test again fails, continue drying. After a period, take a few again, and repeat. If after this you get failure of first coat. it is not drying that is the problem, as long as the coated alloy reaches adequate temperature and for long enough.

What is solvent you are using?
Before using a mix, how long is it mixed before applying to alloy?
How much coating mix are you making up for coating?

I do get a perfect first coat now in 12 minutes. Oven 200. +/- 5°C. Boolits hit 205 C max, IR meter. My Reply If your oven is set at 200C plus or minus 5C, I am wondering how alloy had reached 205C? My understanding on ovens, is that to get to 205C the oven may go higher to force load to that temperature

I repeat that and smash fail. Please explain this in detail, I don't understand what you are doing here


Attachment 219018

Attachment 219020.


I have old bullets, new bullets,WW, linotype, pure lead,water quench,not water quench etc...

This is only complicating your life. Simply use one alloy that was cast, and do your tests with that. Do not quench after baking, and simply fan cool baked alloy.
I am also considering, that Water may be forcing its way under baked coatings and lifting them with sudden cooling.[/I][/I]

[Ausglock]

The Acetone is UN1090???
Just for ****sNgiggles, do a first coat of 3mls per 2KG of bullets.
Bake for 12 mins.
Let cool under a fan etc etc.
apply 2nd coat of 5mls. air dry under a warm fan.
Bake for 12 mins.
do the smash after each coat.
Use the KG for this. OK?

You are pre-heating the oven to 200 deg C BEFORE inserting the tray of bullets.....?
Please do not water quench.
Can you get 2,6,92 alloy? It would be good tto use as a control test.
All these cheapskate alloys give me the horrors...

When you mix the coating. Do you leave it for 30 minutes to react before you use it to coat??

[Ausglock]

Tiny flaking will still shoot fine. Try them.
Have you slugged your bore?
size 1.5 thou over bore size. Eg bore .355 size .357

[ioon44]

I think what is too much flaking depends on the gun they are being shot out of.
I have shot coated bullets out of a .45 ACP that had some flaking and did not lead the barrel. There are a lot of factors to consider, does the bullet fit the barrel, does the reloading process damage the coating.

One mistake I made was trying to use too much coating on the second coat or third coat, this caused flaking even when the first coat passed the test.
I get the coated bullets up to 50 to 60 deg C for 30 minutes, this insures the first coat is dry and ready to bake and my convection oven runs 200 to 210 deg C.

[slide]

I am not an expert like Joe and Ausglock. Those smashed bullets don't look that bad to me. From my experience it is not unusual to get a small amount of flaking on a bullet with lube grooves. The tumble lube bullets are even worse. I don't pay attention to it anymore unless it is a lot of flaking. Like Ausglock said,it doesn't hurt to size your bullets a little bigger.

[slide]

Did you say you were using an IR meter? Is that a handheld temperature gun?

[slide]

That may be part of your problem. Those are made for solid objects,there are gaps between those bullets. Have you got an oven thermometer or something you could put in the oven with the bullets? Here is what I do. this is Ausglock's idea. Here we call them multi-meters. They measure volts,ohms,temp and they will go up to 1200 degrees F. I drilled a hole halfway into a bullet. these meters come with a thermocouple lead. It is just a thin wire. the end of the lead is taped into the bullet with high heat aluminum tape. It goes in with the bullets when they go into the oven. The lead is thin enough the door will still seal. I don't pay any attention to the temp until it hits 360 F. then I start a countdown timer set for six minutes. Remember Joe's 357 F. Works great! As far as the coating I mix as you do. I put 1/2 tablespoon which is 6 mils onto six pounds of bullets.I wish I could post photos. I need to get situated where I can.

[slide]

You'll get there. There is a learning curve to this stuff. Just don't overthink things.

[lazs]

petlander.. your smash test looks good to me. I have never had a bullet fail the acetone rub test. I have had some flaking with some colors but no big deal to me. Any bullet you buy from the commercial people who HT coat will pass any test I have seen.. Not sure passing the smash test is the end all to be all thing.

To be fair.. . I always perform the smash test after the second coat.

lazs

[HI-TEK]

Petander,
Is your oven fan forced?
I am thinking, that if you have fail with solvent test, you are not getting all the loaded coated alloy to correct temperatures.
The reason for my thinking this way, is that oven temperatures do not correlate well with a specific load if air is not well circulated.
Ideal conditions inside an oven is to have a Cyclone fan forced air mixing.
This evens out hot and cold spots, and also gets the total load up to correct baking conditions very fast and very evenly.
If your oven is simply a convection oven and no fan inside, I am thinking that this may be your cause of variations with results you are getting.
The amounts of coating you use seem OK, but the areas that are important,
1, Dry well, and test bake a few first, before baking the bulk, and
2, make sure they bake correctly/adequately with the load you place into the oven and don't overload, especially if there is no fan.
No magic involved. As per previous advice from others, don't over think this process.
If you are considering consistent and or larger volume production, I suggest that you invest in a good fan forced oven, even a second hand will do.

[wlkjr]

How soon after the first coat is cool do you apply the second coat and cook?

[Tazza]

My understanding was you don't need to wait. As long as it's cooled off enough, you can go for another coat.

I thought Ausglock mentioned that he would coat and cook an entire batch in one hit. Take a tray out and let it cool while another goes in, coat, let it dry while the others are cooking and then cook the newly coated/dried ones.

As Hi-Tek has mentioned, you must unsure the coats have fully dried between coating, heat helps it dry faster and fully. Ideally higher than ambient then you know no moisture is left in there.

[razorfish]

“The Toast Test”. I bought my convection oven years ago. It as dual squirrel cage fans and moves a lot of air. It was sold as a “parts only” oven, but when I got it working, the first thing I did was a “Toast Test”. My oven now makes absolutely perfectly even toast and very nice Hi-Tek boolits (No, I didn’t eat the toast).

I’ve seen others test with Pizza but I was able to do the same with bread and test every corner of my oven.

[wlkjr]

You can apply second coat as soon as bullets are cool enough to handle. ( 75-80F) 2nd coat should be adequately dried same as first coat before cooking.

That's exactly as I have been doing but I wasn't clear in my question. It was directed to Petander. I haven't had any problems in my process.

[HI-TEK]

[QUOTE=razorfish;4353825]“The Toast Test”. I bought my convection oven years ago. It as dual squirrel cage fans and moves a lot of air. It was sold as a “parts only” oven, but when I got it working, the first thing I did was a “Toast Test”. My oven now makes absolutely perfectly even toast and very nice Hi-Tek boolits (No, I didn’t eat the toast).



razorfish,
That is a great oven. I bet many would like one, 3 shelves and fan forced even heating.
I like the "toast test". It really shows even heat being circulated inside the oven.
Glad you did not eat the toast.