Treating molds with "Strike Anywhere" matches.....

[Dschuttig]

Maybe this is known to some of you already, but I recently had a flood in my basement which put my dehumdifier out of service for a month. All of iron molds were already coated in oil, so moisture wasn't a problem. I never coat aluminum molds in anything, since one of the "perks" of aluminum molds is that they don't have to be oiled and can be used right out of the box without being scrubed down. Well after the dehumdifier failure, the moisture content of the basement went way up, but I wasn't worried about the molds. So now that everything is fixed, I broke out a NOE 6 5 Cavity 6.5mm mold and found significant aluminum corrosion on the first 2 cavities! More on the first, but bleeding over to the second. I was stumped. Checked a few others, found the same isuue with the first one or two cavities, but not all the molds. The older ones had no signs of corrosion whatsoever. After some scrubbing, I don't believe the molds were damaged a lot, maybe enough to ruin the super smooth finish on a bullet, but nothing that would effect function. I believe that left unnoticed, it would have caused actual damage. My wife, who is a materials engineer, who works on corrosion problems day in and day out, was surprised that aluminum could corrode that fast, and said there must be catalyst. So after some careful studying, I finally figured out that it was the the strike anywhere match tips. I ran out of "strike on box" type last year and grabbed a box out of the camping supply (strike anywhere). It seems that all of the molds treated after that showed corrosion. It would also make sense, since after the first cavity, most of the tip was burned off, leaving residue in only the first cavity, where the rest was coated in carbon from the stick of the match.

Anyway, this is my best guess, and seems the most logical. I believe the tips of strike anywhere matches are a very similiar compound to chlorate primers, so I would steer clear of them when treating any mold.

[montana_charlie]

You have discovered a new reason to keep mould cavities free of all foreign substances.

CM

[Dschuttig]

I would kinda disagree... I have lee molds that I smoked years ago, that now have a brown/black "hue" to the inside of the cavities from being smoked many moons ago, that have never corroded and cast beautiful bullets every time, with perfect angles (No rounded edges) even with nearly pure lead.

[montana_charlie]

Do you have any moulds that you don't smoke the cavities in?

[Dschuttig]

Iron, brass stuff. As far as aluminum goes, I can hardley ever get a untreated lee mold to work with alloys that are soft. I have switched to using half range scrap with wheel weights to make my supply last longer, but it makes fill out a bit harder, even when the mold is hot.

[longbow]

Well, I am a mould oiler! I oil all my moulds ~ iron, aluminum and brass. Iron because iron rusts, aluminum because not only can aluminum corrode in the right (wrong?) conditions, as you have found out, but they also have steel sprue plates and same with brass and the steel will rust.

For me, cleaning a little oil off a mould before use is no big deal. Many find that bit of work too much trouble. That's fine, whatever floats your boat.

Now having said that, I note you did not say there was any rusting of sprue plates. You should check carefully because a film of rust on the underside of the sprue plate could damage the top of an aluminum or brass mould first time you open the sprue plate.

Not sure about needing a catalyst. Aluminum has to form an oxide layer so as not to corrode further and untreated aluminum can get localized corrosion (white fuzzy stuff) and pitting. Where I have seen that mostly though is around the coast due to salt water. Not saying you are wrong about the matches though. Strike anywhere matches have sulphur and phosphorous in them so it is entirely possible that some deposit was left and reacted in the high humidity.

The older moulds may have enough oxide and/or "smoke" build up to prevent corrosion.

I used to smoke moulds but found that if the mould is good there is no need. So, now if I get a mould that doesn't cooperate with releasing boolits it gets a good going over to check for burrs and usually gets a light lapping (Lee-menting for aluminum moulds). I have had no problems with my Mihec, Accurate or NOE moulds but have lightly lapped several Lyman and Lee moulds. After lapping, no problems.

My thoughts and what works for me.

On the upside, corrosion products usually run much larger volume than the parent material so a bit of corrosion looks worse than it is. You have cleaned them up and probably found that out by now. I'll bet they cast just fine.

Longbow

[mold maker]

I've never used a mold that still had the residue of smoke in it. If previously used, the first thing i do is clean, followed by cleaning again. I have a dampness problem that causes rust on any untreated iron surface. The aluminum molds have never shown oxidation, except on the handles, and bolts.
My community just had 9-13 inches of rain in less than 10 hrs. (not a misprint) My basement and loading area had 7" more than the drains could handle.
My moulds were safe in ammo boxes even though a couple floated.
Don't depend on such things as dehumidifiers. They always fail at a crucial time

[rsrocket1]

I smoked my first 3 Lee molds (45/40/357), but my latest was a 356-120-TC and I simply boiled it in water, washed it a couple of times with Dawn detergent, cleaned it off, lubed it and started casting. The bullets fall out just as easily as if I smoked the cavities. It seemed as if a clean aluminum mold works as well as a smoked one.
1062 bullets in a 3 hour session yesterday (set up to clean up).

77491

[MtGun44]

Smoking has never done anything beneficial for me. Stopped doing it years ago,
bare naked molds work fine.

Bill

[Walter Laich]

I've had good luck smoking both iron and aluminum molds. After cleaning use a wooden kitchen match to smoke molds. Seems to help get good bullets, no wrinkles, dropping sooner.
YMMV

[Dschuttig]

Done it for years with kitchen matches, but I'm pretty sure the switch to strike anywhere type left a hydroscopic compound on the mold. My point of the post was to be cautious of these type of matchs.

[RobS]

I use a plastic air tight, rubber seal in the lid ammo box for all my molds. No oiling or anything after I use them just get the molds back into the ammo box as soon as they cool. I should also get some of those small moisture absorbing packs to throw in the box but just haven't. Saves my molds from moisture and the "what if" of other types of storage.