First HT Boolits - Results and Questions

[HI-TEK]

[QUOTE=Taterhead;4667871]Ok guys.

But here is the deal: HOLY SMOKES! These loads smoked BADLY. I don't remember commercial cast HT bullets smoking. Just a little of that distinctive smell. That tells me I need to tweak something. Just not sure where to start diagnosing. Hoping for ideas.

Taterhead
from what you described, it may be as simple as not baking coatings long enough or they had not reached 180C and kept there for another 3 minutes afterwards..
Under cured coatings may cause the "smell" and possibly smoky gasses . Simply check baking conditions and possibly bake a little longer. The load taken from oven is or should be generally at 190-200C after baking is finished.

[Petander]

The load taken from oven is or should be generally at 190-200C after baking is finished.

An IR thermometer comes in handy here. Helped me a bunch.

I use a digital "stick in" steak meter with a probe, a mechanical round metal "clock style" one and the IR shooting thing. All read differently,steak-o says 185 when mechanical says 200 and IR 205 at the end of bake.

Oven dial is at 200.

[Taterhead]

[QUOTE=HI-TEK;4669635]

Ok guys.

But here is the deal: HOLY SMOKES! These loads smoked BADLY. I don't remember commercial cast HT bullets smoking. Just a little of that distinctive smell. That tells me I need to tweak something. Just not sure where to start diagnosing. Hoping for ideas.

Taterhead
from what you described, it may be as simple as not baking coatings long enough or they had not reached 180C and kept there for another 3 minutes afterwards..
Under cured coatings may cause the "smell" and possibly smoky gasses . Simply check baking conditions and possibly bake a little longer. The load taken from oven is or should be generally at 190-200C after baking is finished.

Interesting. I might need to get an IR thermometer. The bullets turned from red to more brown, so it seemed like plenty of heat. Maybe not.

I'll keep at it with your suggestions in mind.

[HI-TEK]

[QUOTE=Taterhead;4670031]

Interesting. I might need to get an IR thermometer. The bullets turned from red to more brown, so it seemed like plenty of heat. Maybe not.

I'll keep at it with your suggestions in mind.

Taterhead,
discolouration's can result from coated projectiles being too close to heating elements, causing radiation burn where your load directly faces heating element. The coating externally is burnt, but alloy may not be at adequate temperature.
An infra red thermometer at least should tell you quickly the actual temperature of the alloy. Best alternative is to place load away from heating elements, and have very good air circulation, fan forced air inside the oven.
Other problem with reading temperatures with a thermometer, without having a fan, is that it simply measures air temperature at a certain point. That does not directly relate to actual temperature of your load in the oven. Further complications can occur, with large swings of temperatures due to poor quality thermostat inside oven. I have heard of swings of plus or minus 50C from set temperatures as indicated on knob control on the oven.

[Taterhead]

Well, after additional testing, my first batch was a total bust after all. I got pretty significant leading in my barrels. I did not look closely enough initially to notice. Identical loads with PC don't lead. Either do commercial HT bullets in the same ammo config. Period.

I'll go back through the process again very carefully. But first I need to cast more bullets. The batch of 300 or so that were HT coated will get melted. I won't load those again.

My oven is pretty good. It drops about 20F when the door is opened to load a rack, and takes about 5 minutes to recover. Temps also don't swing much as it cycles. It is a higher quality convection oven than most cheap toaster ovens. I've also moved the thermometer around to gauge hot/cool spots. Nothing to note. I think the convection setting distributes heat pretty evenly.

So I'm going to look to the "jerk behind the trigger" and re-assess my steps. Mixing, application, will definitely dry much longer.

Also an IR thermometer is sounding more and more like a good idea so that I can see what the bullet temps are.

Thank you all very much for the help.

[Petander]

The batch of 300 or so that were HT coated will get melted. I won't load those again.

.

Why not bake some of those boolits another 10 min and test? They will turn dark but doing that might tell something.

EDIT: I don't mean to shoot them. But test especially wipe. Most probably your coating didn't bond right because of inadequate baking. Too hot doesn't compensate for not enough time. I have baked dark bullets that fail wipe.

[HI-TEK]

.

Why not bake some of those boolits another 10 min and test? They will turn dark but doing that might tell something.

EDIT: I don't mean to shoot them. But test especially wipe. Most probably your coating didn't bond right because of inadequate baking. Too hot doesn't compensate for not enough time. I have baked dark bullets that fail wipe.

I just want to add a few things.

After baking, what was temperature of load when it was taken out of the oven?
I have asked this, but at this stage this is not known, so we don't really know if load in oven reached correct temperature and held there long enough for correct cure.

1. Extra re-heating will not improve bonding, but extra heating will damage colour.
Correctly coated product was baked at 200C for 5 days, it went Black, but passed all tests and shot most accurately. (this was dried adequately before baking.)

2. Wipe test matters; Wiping adequately baked coating, if not dried well before cooking, can cause colour remaining on the wipe material/cloth/paper. The colour removal may not be inadequate baking, but mainly can be caused from wiping fine surface fragile "bubbles" that form on the surface, that are formed and set, when moisture expands during baking. (Orange Skin)
The small coloured particles that are wiped from baked surface, are same colour as the rest of the coating, but it is not dissolved colour but dust type particles that are really not solubilised at all. All that is being done with solvent wipe test
is busting these small bubbles/blister tops, which then show up on wiping material as a colour..

3. Again, I refer back to applying and drying first coat. It is not rocket science. Coat, dry well, and when you think it is dry, test bake only a few first.
After baking test samples, cool, and test with solvent wipe, (to check if coating has cured) and then, smash test, and if you are suspicious, size a couple. If first coat is done well, it should pass all three tests.
I must repeat, DO NOT TRY TO COAT A SECOND TIME, UNLESS FIRST COAT PASSES ALL TESTS.
Re baking will not reactivate poorly bonded first coat, and applying a second coat will not fix bad first coat.
If first coat fails tests after baking, it is a re-melt, so being a little more thorough with getting first coat right in the first place, is best solution.

[Taterhead]

I just want to add a few things.

After baking, what was temperature of load when it was taken out of the oven?
I have asked this, but at this stage this is not known, so we don't really know if load in oven reached correct temperature and held there long enough for correct cure.
...

That is a great question, and I wish I knew the answer. I did not have a way to measure the temp of the bullets.

I'll look for an IR thermometer.

[HI-TEK]

That is a great question, and I wish I knew the answer. I did not have a way to measure the temp of the bullets.

I'll look for an IR thermometer.

Ebay has these IR thermometers, and they are reasonably cheap, if you need to rely on any repeatable results.

Essentially, the oven is simply an enclosure (insulated hopefully) that is needed to concentrate heat into product.

Most even and fastest way to get the heat into product, is a mini cyclone air mix in the oven (fan forced).

Cure requirements, are that alloy & coating get to 180C and then stay there or above for another 3 minutes.
(that is, assuming the product is totally dry before baking, all should be OK)

[Taterhead]

Ebay has these IR thermometers, and they are reasonably cheap, if you need to rely on any repeatable results.

Thanks for the tip. I will look into that.

Most even and fastest way to get the heat into product, is a mini cyclone air mix in the oven (fan forced).

My oven is a convection type, so it circulates air by fan. It has been terrific for the thousands of PC boolits I've coated. Good to go here.

[ioon44]

Taterhead, Try putting your trays of coated bullets out side in full sunshine and on a dark surface for 1 hour, the temp should reach around 140 deg F which is almost to hot to touch.
I don't think you can get much dryer than that, it works for me every time.

[RobS]

With Hi-Tek, once I put the boolits in the convection oven I look for the temps to get back to 390 degrees and then I start a 10 minute timer. I have the oven set for 400 degrees with a PID unit. This seems to work and has consistency to it.

Process:

1. coat
2. set tray in front of small fan heater to dry
3. put tray(s) in oven
4. pull trays and put in front of fan to cool
5. repeat

[HI-TEK]

Thanks for the tip. I will look into that.



My oven is a convection type, so it circulates air by fan. It has been terrific for the thousands of PC boolits I've coated. Good to go here.

Taterhead,
If you have fan forced air circulation that is ideal.
However, you simply cannot compare powder coatings with Hi-Tek.
Powder coating does not absorb moisture, and no solvents are used, and has totally different chemistry.
What ever moisture is produced during heat cure, is gassed out during baking and baking time is generally much longer.

The baked powder coatings do have a more porous internal structure, and additives let majority of moisture to escape.

With Hi-Tek the solvent and coating will absorb moisture. When drying Hi-Tek, it forms a tough impervious dry film, which can trap absorbed moisture. If this trapped moisture is not removed by adequate drying before baking, it will cause problems.

[Petander]

I did 8 lbs of 425 grainers in a single bake the other day. Candy Apple Red. Three coats.

At 6 min I shot them with IR,reading 187-195°C. At ten min they were 195-200°C and I took them out. I'm still getting them a bit dark so they don't need to get that hot (hard to say what REAL temp is). Time may be right.