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master53yoda

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I would assume (you know the assume statement) that using sufficient ventilation would be going on when firing a furnace due to the high possibility of CO in the flue gasses and in most cases more heat then a non ventilated environment can handle. The exception to this are those that are using electrical heated furnaces such as electrical kilns for melting. The need for high ventilation during drossing and degassing is still required.
 

tjwal

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I’ve used a commercial flux for some of my castings. As far as I could find out it was mainly potassium chloride. There is no noticeable reaction when it is stirred in, no bubbling or off gassing. What is noticeable is that the dross is more powdery and is way easier to skim off.
From what I have read is the pool tablets are used to remove hydrogen from the melt and there is a very noticeable reaction. Hydrogen causes small bubbles(porosity) in the casting.
For my purposes the potassium chloride is good enough and appears to be safe to use.
 

awake

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Out of curiosity, does anyone know if chlorine gas is actually release with any of these fluxes? I noted that the various ingredients that had been talked about all seemed to be compounds with chlorine ... but that doesn't mean the chlorine gets released as such. After all, I regularly consume sodium chloride without ill effect ... at least, unless I consume too much of it!
 

lee webster

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I seem to have missed a conversation about an interesting subject. De-gassing aluminium. Some do it, some don't. I have watched dozens of video's concerning the ( I had to pause for a mo, my 3D printer has just been delivered) casting process, and de-gassing. None of the video's of de-gassing taking place even hint of any dangers. I would like to learn more. I think I am favouring an electric furnace, I have no idea of running costs, I just prefer the 'cleaner and quieter' aspect of it. I have read a comment that maybe electric furnaces might produce a cleaner melt, less oxygen. Any thoughts?
I haven't had any email alerts sent to me about these recent postings. I just thought my original post had faded away.....
Right. Down to serious modeling in Solidworks, and FreeCAD. before I attempt to print out bits of my engine.
Lee ( the same Lee who has posted on other forums! )
 

Cogsy

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Out of curiosity, does anyone know if chlorine gas is actually release with any of these fluxes? I noted that the various ingredients that had been talked about all seemed to be compounds with chlorine ... but that doesn't mean the chlorine gets released as such. After all, I regularly consume sodium chloride without ill effect ... at least, unless I consume too much of it!
The melting of the salts shouldn't upset their stability much/at all so negligible chlorine gas (if any) should be released. From the papers I've just been reading, it seems the molten salts rising up through the molten metal use a mixture of absorption and mechanical floating to bring the impurities, including hydrogen, to the surface, as well as creating a barrier over the surface to limit re-absorption into the melt. So chucking a handful of salts on the top of the melt might help prevent more gas getting in but likely won't remove much gas that's already in there. Next melt I think I'll try making packages of salts in aluminum foil and mechanically sinking them to the bottom of the melt as I've seen others do.

Edit to add: Commercial processing processes do often include chlorine gas (and others) being injected directly into the melt but we don't want to do that at home obviously!
 

skyline1

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I don't know what gasses are actually released but the commercial degassing tablets I used to use (Foseco de gasser 190 IIRC) made an awful lot of smoke and fumes I had an extractor fan right by the furnace and we left the doors open when degassing. masks too you wouldn't want to get a lungfull of it.

They had to be plunged to the bottom of the melt with a sort of basket on a stick affair which made the melt bubble and fizz most alarmingly and there were small flames on top.

All in all a rather scary process but it worked really well giving really good metal with no porosity at all.

I expect the methods have changed nowadays with probably less unpleasant chemicals involved.
 

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