Yes,IR was reading 188-194°C at the end of bake. Bullets were above 180 for the last four minutes. Or 3.45...Originally Posted by HI-TEK
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Yes,IR was reading 188-194°C at the end of bake. Bullets were above 180 for the last four minutes. Or 3.45...
Petander,
That is very interesting and encouraging indeed.
Can I request, if you you please do more tests, by increasing cook time, at an extra 1 minute intervals, until the coating starts to go Green or change colour.
If possible please record final temperatures, and photograph each result, after each 1 minute extra cooks, and this will also determine just how long the coating can be baked at a set temperature and remain colour stable.
Later progressive photos can be then directly compared.
With these tests, being carried out in same oven, we can be certain what this coating will withstand, before any noticeable changes take place.
Thanking you much in advance,
Will do.
I have no more uncoated bullets to bake TruBlu again today but I'm about to finish cooking Zombie Green and TMG Gold right now. I'm using the same 180°C oven temp setting. Observing with IR again.
It's possible to manually fight radiant heat a little. When I open the door for a couple of seconds every minute after six minutes of the bake,it slows down excessive heat build-up. I bet the bullets would go above 200°C after 10 min if I don't open the door to take measurements. Air inside stays around 180°C.
If I ever get a PID I'll put the thermocouple in a dummy bullet.
All these are the same 180°C bake. Yes that's my oven temp.
I'm following bullet temps with an IR meter. Bullets hit 180°C @ 5.30 min,then they get hotter with radiant heat , finally being 190-195°C @ 9 min when they come out. I know it sounds confusing but my oven AIR TEMP is 180°C. For example,the bullets are 190°C @ 7 min. The 2 kW element radiation warms the bullets hotter than the oven is.
Could it be that I'm eventually getting Zombie Green look right?
All these are the same 180°C bake. Yes that's my oven temp.
I'm following bullet temps with an IR meter. Bullets hit 180°C @ 5.30 min,then they get hotter with radiant heat , finally being 190-195°C @ 9 min when they come out. I know it sounds confusing but my oven AIR TEMP is 180°C. For example,the bullets are 190°C @ 7 min. The 2 kW element radiation warms the bullets hotter than the oven is.
Could it be that I'm eventually getting Zombie Green look right?
Petander,
You are correct with radiant heat.
If you think about a simple situation, if you have an air temperature of say 30C outside in your garden, if you place a piece of steel outside, that steel becomes much hotter than the 30C air temperature.
I have had a steel gate at 58C when air temperature outside was only 30C.
The reason for this can be mainly explained as below;
1. Radiation is absorbed from heat source (Sun), in an oven, from heating element.
2. The steel does not get enough air flow around it to get rid of the excess heat build up.
3. Air is a very poor conductor of heat. Without fast air movement and circulation around an object, the static air will not remove built up heat adequately, to the same outside air temperature of 30C, so the metal builds up more heat, and way above ambient air temperatures.
This is the reason why I keep repeating my suggestion, to have a mini cyclone inside an oven, to move air around, to even out such heat build up with products being baked.
Also, measuring air temperature inside an oven, will not be representative of the temperature of items being baked.
People get over baked loads, and state that the oven temperature was at 180C. When looking at the final colour of the coating, it quickly exposes true conditions, which does not agree with the 180C as being assumed as being the product temperature.
Spot on,Joe.
Baking cakes or steaks is different because they are full of water that evaporates and prevents burning.
Here you can see 8 min and 9 min colour difference,I exaggerated "colour saturation" a little to see better. In another words, 3 min @ 180-190°C vs 4 min @180-190°C.
I have fired many of those 8/3 min bullets in 38 Special. They are fully cured and do not lead.
Petander,Will do.
If I ever get a PID I'll put the thermocouple in a dummy bullet.
PID Controller are reasonably cheap.
The benefit of a PID controller is, that the temperature sensing probe that is inside a Cast alloy sitting on top of your load, when this is sensing probe is telling the PID that temperature is higher than the PID settings, the PID simply turns off heating element.
That way you take care of your load getting too hot from Radiant/overheat.
You also save on power, and get very even reproducible baking results.
It is important, that PID controller is only wired to heating element.
You can also benefit with a separate micro switch on the oven door, that will turn off oven fan when you open oven door. That way you lose less heat when opening the oven door and you don't get a hot blast into your face when opening the oven door.
Yep I know how PID:s work. I'm a "half-electrician",dropped off from an electrician school for rock'n roll back in the day. I was building radio transmitters and guitar amps when I was 15.
This particular oven has multiple elements and fans controlled by multiple thermocouples already. There is a continuous fan and another blower that goes on/off,adjusting the temp. It is working individually from the elements.
If I go PID I'll use another over with continuous fans and a simple circuit to begin with. This one holds the air temp extremely well as it is now. I can adjust my bullet surface temps pretty accurately,now that I have been following them with an IR meter every minute. Left,center,right. I know the graphs.
Even with a PID and a thermocouplebullet,this oven will have the same cold/hot spots unless it gets more circulation. More circulation will mess up the currently working design... Temperature variation is not big enough to show in a batch of bullets,I get an even bake with no darker ones.
Opening the door a little for two seconds to take a reading is not a problem. Air temp drops by 2°C,that is actually a good thing when fighting radiant heat. I don't keep opening the door randomly when I bake.
I remember when I got the first oven,reading this board I got the idea that it has to be "a cheap toaster oven". So I got the crappiest one there was,an underpowered piece of crap. I did't have coatings yet so I did lots of " dummy load bakes", having probes inside bullets,in the oven,also IR meters... I figured out the bake before actually baking.
All those different temp readings were interesting to say the least. Then when I got the coatings I didn't measure much at all anymore, "knowing" the bake and temps. Well,it was fine except the oven had already lost half of its power without me noticing of course. So I started with underbaking. Haha.
Oh and the biggest reason for my "no PID yet"... when I see a soldering iron I get completely flegmatic and depressed. Can't function.
Somewhere around 1990 I said " life is a never ending cable making". I've been moving,building and maintaining recording studios,small and large,since the 70's... always with that stupid iron in my hand. And pliers. Someone should make an album cover with a soldering iron.
Smashing Pumpk... Bullets,maybe?
Last edited by Petander; 01-07-2020 at 07:51 AM. Reason: Add pic
Petander, just an idle thought, can you put a metal plate (or something) in front of the heating element to reduce the radiant heat?
PetanderSpot on,Joe.
Baking cakes or steaks is different because they are full of water that evaporates and prevents burning.
Here you can see 8 min and 9 min colour difference,I exaggerated "colour saturation" a little to see better. In another words, 3 min @ 180-190°C vs 4 min @180-190°C.
I have fired many of those 8/3 min bullets in 38 Special. They are fully cured and do not lead.
Just wondering what was final temperatures of baked load, at 3 minute time and at 4 minute time.
I suspect, that at the 4 minute time the projectiles were much higher than 180C
and probably more than 195+C.
We have had locally tested product, the final temperature was at 195C after bake. They were all Blue.
I’m going to jump in with a totally tangential question. Has anyone used Hi-Tek as a coating for lead fishing weight or lures? I normally paint my home cast lures with nail polish or enamel paint, but the idea of coating them in bulk is appealing. I assume the coating holds up to water when cured, given that it can survive the trip down a gun barrel.
NRA Endowment Member
Armed people don't march into gas chambers.
I have coated a few sinkers so I could teach the little gran kids to set up their own lines, Young kids being what they are run a higher risk of lead poison in my view. Be mindful you can't coat inside the hole. Regards Stephen. Ps I recently coated a steel lure that was one I got from my grandad and the gold looks good.
Elkins45
Great question.
Many years ago, I used to fish using Snapper sinkers, made from scrap Lead of unknown composition, from 1/4 pound to 1 1/2 pound size.
I did paint by brush, various colours/patterns on the Lead, dried and baked them.
The intent was to cause an attraction to fish with various colours. I always caught a lot of fish with or without painted sinkers, but people on the charter boat we used, were convinced, that I was cheating by using "lures" (painted sinkers) that they had no access to.
I simply said, I use what ever I can to catch fish, that is why I paid moneys to charter boats to go fishing. I don't want to pay and get no fish. I want value for my moneys paid, and, if I don't use every opportunity to catch more fish, I may as well go down to the fish Co-Op to buy fish.
I fished in salt water, and after a while the coating did start peeling off the Lead. It never occurred to me at that time that contaminations in the Lead reacted with the salt water causing spalling and lifting the coating.
Yes,the four minute one was 195°C at the end ,but for less than a minute.
It is blue,the one to the right,9 min, is the same bullet that you can see here,on this page in my previous posts. It's just in a different light so we can better see the slight difference to the 8 min colour.
The same bullet,same bake and batch here all the way. Just a different light.
.
In your bulk, you show Green and Gold. Are these Zombie and TMG?Yes,the four minute one was 195°C at the end ,but for less than a minute.
It is blue,the one to the right,9 min, is the same bullet that you can see here,on this page in my previous posts. It's just in a different light so we can better see the slight difference to the 8 min colour.
The same bullet,same bake and batch here all the way. Just a different light.
Your oven seems to continue heating past the 180C as set. You should not be getting or need to be getting a finished temperatures at 195C.
Coated Cast needs to get to 180C and held there for about 2-3 minutes.
Temperatures should not continue to rise, because this adds to changes of final colours.
At 195C, those colour changes become more rapid and more noticeable.
Coating works OK at 195C, but some like reproducible colour each batch.
Yes I'm just testing here to see how the colours change. I'm not complainining,I don't know why everyone takes my post as me having problems with coatings nowadays...?
Did I get that wrong?
Because of radiant heat,the bullets are 180@5.30, 185@7.00 , 190@8.00 and 195@9.00. That's in the middle of the tray,left side bullets are 5C lower, right side 5C higher. That's how the oven behaves when air is 180.
Baking cooler is not a problem but it took me 12 bakes to confirm the temps above, I don't want to go lower five degrees and spend another day observing right now.
Especially because these postings of mine seem to to cause more confusion than good.
I go shooting now.
Petander,
Please do not think that I have a problem with what you have done. It is great work.
I am not confused at all with your postings.
The questions I asked, simply is educating me with how different conditions affect final coatings, and, effects of radiant heat, versus set oven air temperatures.
You have clearly shown why colours may change. That is great.
There are many who would have not be aware of what was going on, when they had products that were over cooked, when they had a set temperature for oven.
From measuring oven air temperatures, they assumed from oven settings, they should have had produced correct results.
We now know, why this happened with your testing and posting.
Thanks much
Hey Joe,
Got a question. This is off subject. Does hi-tek coating once it is baked have a BHN? I have seen the photos of the sawed bullets and realize the coating is thin. Just curious.
Boolits !!!!! Does that mean what I think it do? It do!
Slide,
that is a great question. The BHN is not something that has been tested.
Once coating is applied, and baked, doing a test may or may not give an adequate result.
The coatings are generally thin, and in majority of cases, final coating thickness is about 1.5 to 2 thou.
I really cannot advise how an accurate measurement can be made for a BHN.
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