Annealing color change

[1raggedhole]

I bought an Annealeez machine and am very happy with it. Easy to setup and a huge time saver. I annealed about 1400 rounds Rem 204 Ruger and 450 rounds Rem 20 Vartarg.

I setup the machine to just turn the 750 deg F tempilaq clear (inside the neck). With no changes to time or flame, I noticed about 10 pcs of the 204 Ruger brass turned pink, usually less than half way through the flame time.

Today I did about 150 pcs of Lapua 6BR brass, and had the same pink color change on about 7 pcs, again with no change in flame or time. These turned pink almost immediately after going into the flame.

Anyone know for sure what causes this? Since the time was the same, I see no reason not to use them, but it sure looks funny.

 

[MagnumManiac]

The pink hue is generally caused by the gas in the brass just starting to escape.
Maybe the alloy is slightly different on those cases causing the anneal to be slightly more.

When I worked at ADI/Thales here in Australia, the brass cups that the cases are made from would be pink after the first anneal. And be pink on the final anneal before the shoulders were formed.
The final anneal for the neck final draw would look like the normal rainbow with a pink ring just below the shoulder.

Cheers.

 

[1raggedhole]

I like that answer. Cheers!

 

[rwj]

I’m wondering if it’s the result of something coating the case neck/shoulder area and/or contaminants in the annealing gas? Does the pink discoloration also appear on the ID surfaces?

 

[1raggedhole]

Double check that those 'odd' pieces are turning/rolling while in the flame... I see things like this when the brass stops while in the flame, re; over heating

I was watching them carefully, and they were most definitely turning.

 

[Texas10]

I would guess that your torches are surging and overheating the brass intermittently. Orange is the result of Zinc in the surface of the brass being oxidised (burned off) but will usually polish out back to normal, if it bothers you.

I would set those aside and use as sighters or warm up rounds. You might notice a different feel while seating a bullet, and the shoulders may collapse.

 

[rwj]

I would guess that your torches are surging and overheating the brass intermittently. Orange is the result of Zinc in the surface of the brass being oxidised (burned off) but will usually polish out back to normal, if it bothers you.

Do you think a pressure regulator installed in the supply line would mitigate this possibility?

 

[Texas10]

Yes, unless the Annealeeze already has one built in.

 

[JimSC]

color changes on the brass are due to a thin oxide layer that forms on the surface of the metal. The thin film will enhance some wavelengths while reducing others. The rainbow effect is caused by the varying thickness of the film enhancing some wavelengths of light reflecting off the surface of the metal while reducing other wavelengths. Try a quick experiment, clean some cases with alcohol immediately before annealing being careful not to touch the neck area when placing the case in the machine. Then anneal some from the same batch but before annealing rub the neck/shoulder area between your fingers before annealing. There should be a noticeable difference in the oxide layers

 

[Ccrider]

After annealing, some pieces change color some do not, and some not as much. This does not mean they are not annealed equally.

 

[Capt45]

Probably varying alloy. Were the headstamps the same?

 

[BLUESGUNNER]

Do you use a graphite powder on the neck to neck size. Maybe a little residue left over. ??? Just throwing it out there?

 

[Webster]

The pink hue is generally caused by the gas in the brass just starting to escape.
Maybe the alloy is slightly different on those cases causing the anneal to be slightly more.

When I worked at ADI/Thales here in Australia, the brass cups that the cases are made from would be pink after the first anneal. And be pink on the final anneal before the shoulders were formed.
The final anneal for the neck final draw would look like the normal rainbow with a pink ring just below the shoulder.

Cheers.

There is no gas escaping from the metal.

 

[spclark]

1raggedhole, are you using Propane to power your torch or maybe you're thinking MAPP gas will work better / faster?

Only time I've seen that kind of coloration on brass I've annealed (with Propane) is when I've been trying seriously to overcook it.

Those cases look pretty dark too... I'm wondering what in your pre-anneal process there might be that's maybe leaving something on your cases that's causing them take on that look....

 

[magic mike]

You might consider doing a "spring back" test and see what happens. If you slightly squeeze the discolored necks to an oval shape with a pair of locking pliers and they don't spring back to their original round condition they're toast.

 

[JimSC]

think about this, if you could "leech" the copper from brass by heating, it would be impossible to melt brass for castings. The pink is cuprous oxide, polish it off with some Nevr-Dull or other ammonia free polish. Cuprous oxide is mostly found when rescuing old range brass and then cleaning it. The black or cupric oxide will be removed by the citric acid but the red remains. Some contaminant on your brass reacted by forming cuprous oxide when heated. It is only a few microns thick

 

[Webster]

I bought an Annealeez machine and am very happy with it. Easy to setup and a huge time saver. I annealed about 1400 rounds Rem 204 Ruger and 450 rounds Rem 20 Vartarg.

I setup the machine to just turn the 750 deg F tempilaq clear (inside the neck). With no changes to time or flame, I noticed about 10 pcs of the 204 Ruger brass turned pink, usually less than half way through the flame time.

Today I did about 150 pcs of Lapua 6BR brass, and had the same pink color change on about 7 pcs, again with no change in flame or time. These turned pink almost immediately after going into the flame.

Anyone know for sure what causes this? Since the time was the same, I see no reason not to use them, but it sure looks funny.

View attachment 1147797

I wouldn't worry about it since it occurs way before you reach 750F. Could be some cleaner or chemical on the surface. Steel wool a bunch with 0000 SW wipe off with a cloth and see if it still happens.

 

[dcali]

I’m not an expert on this by any stretch, but zinc does vaporize at relatively low (but still very high) temperatures at standard atmospheric pressures. The melting point of zinc is under 800 F. All metals will do this to one degree or another, which is why NASA has very strict requirements on the materials that are permitted in satellites (which will be in vacuums, and potentially high temperatures, both of which increase the outgas rate).

They have a whole set of rules for how much such and such material will outgas and potentially find its way into a sensitive camera mirror or whatnot.

We used to test stuff in giant vacuum chambers and you’d be surprised by how much crud leaks out of stuff that you wouldn’t imagine could leak anything.

I would imagine that some of this is going on during annealing, although I have no idea how much or why it would turn pink.