This weeks guest on the Podcastiron claims you can degass aluminum with mothballs. Almost immediately after saying aluminum extrusions don’t cast well because they get gassy… but really one of you edjumakated guys tell us why mothballs would degass aluminum Thanks in advance V/r HT1 https://open.spotify.com/episode/6n...A&context=spotify:show:6LGTQ0RtuKd3CeCWp5L4JA
I've never heard of that before but mothballs go from a solid to a gas at relatively low temperatures so maybe it's a same effect as bubbling an inert gas into your melt to dislodge the entrained hydrogen gas,
I suppose it would potentially work at a guess, but the fumes/gases given off would be highly toxic and carcinogenic... We have enough issues with health concerns in the foundry. Don't go adding any more..
There was a urinal cake that contained some kind of chlorine compound (also used for smoke grenades) that was also used to degas aluminium while creating dry hydrogen chloride gas (forms acid in the lungs) with any hydrogen in the aluminium. Mothballs or naphthalene were also used in urinal cakes but is now considered a inhalable carcinogen. Mothballs might be more suitable to deoxidize copper metal similar to using propane to degas copper instead of the old fashioned "poling" with resinous wood logs. I need some sort of aluminium degas method like HT1's sawdust on the melt, maybe a solid hardwood block on top of the melt similar to bronze casting. Edit: the urinal cake/mothball replacement is dichlorobenzene, still trying to find out where I linked it with aluminium degassing. Edit 2: it's hexachloroethane that's used for aluminium degassing tablets: https://en.wikipedia.org/wiki/Hexachloroethane Hexachloroethane is not particularly toxic when taken orally,[12] but is considered to be quite toxic by skin adsorption. The primary effect is depression of the central nervous system.[3] The concentration that is immediately dangerous to life or health is 300 ppm and the permissible exposure limit according to the Occupational Safety and Health Administration is 1 ppm (skin).[12] It is reasonably anticipated to be a carcinogen.[13]
The last time I used Professional Aluminum degasser tablets 1992 they where all Chlorine based, and looked just like urinal biscuits. and if it floated, and you inhaled... well chlorine gas, so if you inhaled it you where in serious trouble. been there done that. I can see the possibility of mothballs working , because they are very Flammable, so if you plunge them to the bottom of the melt, there are two possibilities, one the "burning" would create lots of small bubble, that would scrub out the Hydrogen, and/or the Hydrogen would just be burnt which would form H2O or H2O2 which would boil out, MY High school Science, says that is a NoGo , where is the O2 coming from? If someone decides to try this , two things use New Mothballs , if you preheat keep in mind their flash point is 151F so they will be on fire before they hit the surface of the metal if you dont listen to the podcast, remember there is a warning not to use too much or the crucible will boil over i found some very old aluminum degasser literature that called for .05% (someone help my math), 4 ounces for 100Lbs of metal? I remember using 1/4 of a urinal block sized biscuit for 70 Lbs of aluminum, so a single mothball for a 15-20Lbs melt would be ALOT!! V/r HT1 P.S. I'm not endorsing this method, I just shared it please review the source and make your own decision, P.P.S the podcastiron as a whole is a good listen, there are some very different thoughts, because the people involved are all Formally trained artist ALOT of Masters in Fine arts, so their thought patterns are very different, they often do things that might be pretty, but have no practical use, there is also alot of talk of performance art (alot of us will think of KOR) and of course there is a lot of ego in doing cast Fe. you hear some of them try to divert and get all "mystically" about iron" It's in the earth and stars even our blood" ... so is copper and zinc go cast some brass ;-) I binge listened to the entire podcast this is the first time I have heard any potentially useful info, but if you have to fill 8 hours a day listening to something, its pretty good
