Annealing question

[mitch308]

I annealed around 200 cases last night and around 30 of them have come out with a brownish finish to the annealed area, they were all done at the same setting, has anyone else had this and is it something I should be concerned about

The cases are 223GGG, they were all cleaned and prepared and I used tempilaq 750 to set up the time/ temperature

[VarmLR]

Looks very much like they've overheated and you've burnt a little too much zinc from the brass leaving more copper. Did the torch flame ever turn even slightly orange from blue? If so, that's a tell-tale. I would go by the flame every time, and don't use Tempilaq as it only takes a second or two more from when it starts to melt until over temperature is reached. If you still have the timings you used, it is worth re-checking using another (sacrificial) case, set up and time until the flame at the far end of the neck just turns yellow/orange. As soon as this happens, back off time by half to one second and compare with the time you used. If your time was more than this, chances are, the cases have got too hot.

 

As to why not all the cases have come out the same, I wouldn't know except there may be slight variations in case thickness that make the difference on heating times, but your examples look like they've had different timings so it is odd.

[John MH]

The lower case looks the same as how mine look after they have been annealed. The discolouration is dependent on how much oxidation remains on the case after they have been cleaned and if done very soon after cleaning there will be very little.

 

Flame colour changes are also affected by the presence of an oxide layer on the brass so to judge whether you have reached the correct temperature, or over done it, by judging the flame colour as the oxide burns off is not ideal. Use temperature indicator paint on the inside of the case mouth.

[VarmLR]

The lower case looks the same as how mine look after they have been annealed. The discolouration is dependent on how much oxidation remains on the case after they have been cleaned and if done very soon after cleaning there will be very little.

 

Flame colour changes are also affected by the presence of an oxide layer on the brass so to judge whether you have reached the correct temperature, or over done it, by judging the flame colour as the oxide burns off is not ideal. Use temperature indicator paint on the inside of the case mouth.

 

Very good point, however, if the cases are tumbled first until shiny, this shouldn't really be an issue should it?.

[John MH]

You crack on, I'm sure your flame colour judgement is better than mine and everyone else who uses Tempilaq,

Does a change in flame colour indicate how far the heat has travelled down the case?

 

[DaveT]

I agree with John re use of Tempilaq INSIDE the case mouth so you can see it change due to temperature rather than simply being burnt by the direct flame.

[VarmLR]

It'll be interesting to compare the use of tempilaq and see whether flame colour is an accurate indicator or not. Can't hurt to try. I've never used it, but I'l try some as a double check.

[gbal]

Varm,belt and braces- say 750 degree Tempilaq on necks,450 half way down the case.A double check-neck is correct annealing temperature,lower case is not heated too much...(BS Vortex,double flame,not literally 'hands on" ...the human senses can detect quite well -eg taste of many acids,but litmus is more reliable,and de riguer for the aggressive ones! :-)

 

Also, the metallurgy varies a bit between brass makes(eg zinc content,though much less so within a batch) or treatment oxidation layer, as John says.

 

 

What is curious is that the OP cases are not uniform-same tratment,different outcome.....hmmm...suggests some inconsistency somewhere....temperature or timing or.....?? Tempilaq might help diagnose...

 

gbal

[mitch308]

I noticed last night while trying to set up to do some more cases that i had to turn the torch valve fully open to get a decent flame, so obviously the bottle is running low, perhaps this is something to do with my strange coloured cases, now thinking about it, it was towards the end of my session the previous evening that these cases came out, so could the strange colour indicate they did not get hot enough ?

[John MH]

Use a gas regulator if you are going to do it properly and consistently.

[gbal]

mitch, quite likely-another arguement for a Tempiaq tested case/cases within the batch,after set up...esp. if there is any indication of lowering gas pressure/heat-and/or inspect cases for visible differences..and stop if any are spotted....a bigger gas container/regulator will make this much less frequent....

g

[VarmLR]

Varm,belt and braces- say 750 degree Tempilaq on necks,450 half way down the case.A double check-neck is correct annealing temperature,lower case is not heated too much...(BS Vortex,double flame,not literally 'hands on" ...the human senses can detect quite well -eg taste of many acids,but litmus is more reliable,and de riguer for the aggressive ones! :-)

 

Also, the metallurgy varies a bit between brass makes(eg zinc content,though much less so within a batch) or treatment oxidation layer, as John says.

 

 

What is curious is that the OP cases are not uniform-same tratment,different outcome.....hmmm...suggests some inconsistency somewhere....temperature or timing or.....?? Tempilaq might help diagnose...

 

gbal

 

 

Exactly George.

 

I get the metallurgy things. I'm an engineer by profession. IR spot thermometers also have their uses ;-) However, as said, I'll be trying some tempilaq by way of comparison only if for peace of mind.

[VarmLR]

Use a gas regulator if you are going to do it properly and consistently.

 

 

http://welduk.com/product/regulator-disposable-map-pro-gas-cylinder?gclid=CjwKEAjwzKPGBRCS55Oe46q9hCkSJAAMvVuMIjhrM29sF-92d6535dIPLmnLU9WoLVhN1dQzSv6xjRoCP0_w_wcB

[John MH]

Exactly George.

 

I get the metallurgy things. I'm an engineer by profession. IR spot thermometers also have their uses ;-) However, as said, I'll be trying some tempilaq by way of comparison only if for peace of mine.

If, as the OP has hinted, a gas canister is being used as the fuel is used the pressure drops and that alters the characteristics of the flame and thus the heat. I use a large propane bottle with a gas regulator so the flame when set remains constant. That may be the cause of the variable discolouration.

[John MH]

http://welduk.com/product/regulator-disposable-map-pro-gas-cylinder?gclid=CjwKEAjwzKPGBRCS55Oe46q9hCkSJAAMvVuMIjhrM29sF-92d6535dIPLmnLU9WoLVhN1dQzSv6xjRoCP0_w_wcB

Not what I use.

[gbal]

George has seven 47k propane canisters,and regulator,and several smaller....but all too big,of course,so he might get a smaller one,for his Bench Source Vertex.He's very new to annealing,but reducing gas pressure was one issue,from the first small canister. He does have a fair degree of science knowledge,and does his research/homework.John's helpful post has confirmed this is indeed the way to bypass this issue.

 

V, I'm a psychologist so "mens sana et pace" are desiderata,allowing well informed alternatives.

"Peace of mind" of course-life is geting too short.

 

 

I just hope that Tempilaq has a decent shelf life,as it's not that cheap! :-)

 

g

[VarmLR]

If, as the OP has hinted, a gas canister is being used as the fuel is used the pressure drops and that alters the characteristics of the flame and thus the heat. I use a large propane bottle with a gas regulator so the flame when set remains constant. That may be the cause of the variable discolouration.

 

I agree. It's otherwise burning with gradually reducing pressure from the first time a new canister is used otherwise. I use the smaller canisters only because space is at a premium, and a regulator similar to the last one linked, intended for MAP pro canisters. Not ideal but does the job.

[gunner]

I agree with John re use of Tempilaq INSIDE the case mouth so you can see it change due to temperature rather than simply being burnt by the direct flame.

 

+ 2 i use tempilaq , although im sure its not essential but makes sense too .

[raptor calls]

If, as the OP has hinted, a gas canister is being used as the fuel is used the pressure drops and that alters the characteristics of the flame and thus the heat. I use a large propane bottle with a gas regulator so the flame when set remains constant. That may be the cause of the variable discolouration.

 

Absolutely right!!!

[MJR]

When you buy your tempilaque its a good idea to get a bottle of their thinners at the same time. You can thin the fluid a little and make it easier to brush the inside of the case neck.

[1066]

If, as the OP has hinted, a gas canister is being used as the fuel is used the pressure drops and that alters the characteristics of the flame and thus the heat. I use a large propane bottle with a gas regulator so the flame when set remains constant. That may be the cause of the variable discolouration.

 

I'm obviously out of step here but don't think it's quite so straight forward as that. The pressure in a LPG cylinder of any size doesn't drop as the fuel is used. The pressure drops due to the drop in temperature caused by decompression. All the time there's liquid gas, whether 10% or 70%, in the cylinder the pressure remains constant if you could keep the temperature constant.

 

A CO2 cartridge, as used in an air pistol for example, has a pressure of about 800 psi at room temperature - this stays constant all the time there's any liquid in the cylinder, right down to the last few shots when there is only vapor left. What you do need to do is to allow an element of rest time between shots to prevent temperature drop.

 

A short run with a small cylinder will perform the same if it's full or nearly empty. Keeping your small cylinder in a bucket of water while it's being used would act as a heat sink and keep the pressure constant (not suggesting this is the answer)

 

Using a large cylinder with a regulator tends to overcome the problem and is a practical solution.

[VarmLR]

OK

 

So Tempilaq arrived and I dabbed a line inside the neck of three once fired cases just down into the cases and left them to dry off for a little while, leaving a dull green indicating liquid inside the necks.

 

I set the annealer up, and first using Propane adjusted so the neck had the tip of the inner blue flame about 3 or 4mm from it about mid way down the neck and adjusted timings first using my usual method (ie the non-tempilaqued cases), which resulted in a time of a fraction over 4 seconds. The cases came out with a barely visible rainbow ring just below the necks and the neck remained shiny but a tad darker in shade, turning a slight golden hue. There was no indication of pink or copper discolouration. I repeated this three times using three once fired cases to be sure. I am entirely satisfied that these cases have been properly annealed and to reduce the risk of heat transfer down the cases, I always use hotter burning Propane to shorten the annealing times and the case exposure to the heat.

 

Next, I took the tempilaqued cases and started off at 3 seconds. I few things that surprised me happened. Firstly, the cases flamed off inside the necks and the necks clearly discoloured externally with a slight coppery pink shade appearing near the tops. The tempilaq remained green and un-melted. I upped the timings to 4 seconds, and this time the tempilaq just melted BUT the outside of the necks flamed up and turned pink. I tried this with three more cases with the same result, including one which had been left for 15 minutes after painting. There was no flaming but the outside turned pink, leaving me scratching my head.

 

I am more confident in my own methods after this (expensive) experiment but have a question...just why are the tempilaq cases discolouring on the outside and flaming up on the inside? Should they be left to dry off for more than 5 minutes? (no instructions contained with the bottle). I shook the bottle to mix the ingredients well to begin with. I could only think that the volatiles needed longer to evaporate off, and had flamed up, overheating the necks. Would this sound right?

 

I had to discard 5 cases which look to be ruined. Those with more experience using tempilaq may put me right as my guess is I ought to have left the painted cases for more like an hour than 5 minutes.

[Cienfuegos]

I use tempilap of 800F, is it much ?, I have to buy a tempilap of 750F?

Soy español, perdón por mi inglés...

 

I am Spanish, sorry for my English