My new false bottom. Will it work?

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de5m0mike

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I just built this false bottom for BIAB. Basically the only purpose it needs to serve is to keep the grain bag off the bottom of the pot so it doesn't melt during mash out or if I should need to bring up the temp of the mash for any other reason. My only real concern with it is that the grid is aluminum and the bolts and washers are stainless steel. (I tried to get aluminum ones but couldn't find them anywhere.) Anyway, I've heard there can be some corrosion issues with the two metals being in contact with each other. Do you think that will be an issue with my beer?

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That thing looks great. Galvanic action is what I think its called. I would think that it would work out great. Given that it is only used for a short period of time at pretty much low heat, and the fact you are going to clean it up after you brew, I would guess that you don't need to worry too much. Over time it may have a problem if it stays wet. Use the H--- out of it!
Sanke10
 
Well I decided to boil it in some water for about a half hour before it's inaugural use this weekend and it turned pretty black. Hope that's normal.
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On a side note. I thought it was pretty crazy how when I pulled it out of the water after a half hour boil it was cold to the touch within 5 second. Seriously, it was ice cold when I expected it to be hot. That was crazy.
 
Aluminum turning black when left in boiling water is called conditioning and it's both normal and a GOOD THING... It's, basically, an aluminum oxide coating that is a barrier between the aluminum and what's in the pot...

Don't scrub it off and you'll be a lot happier... :D
 
On a side note. I thought it was pretty crazy how when I pulled it out of the water after a half hour boil it was cold to the touch within 5 second. Seriously, it was ice cold when I expected it to be hot. That was crazy.

Welcome to the thermal conductivity of aluminum... :D
 
Glad Goldiggie knows a little about metals. I was scared for a minute on that one. On another note your screen holes look pretty big. Guess I'm trying to say you might get a lot of grain through it until it establishes a good filter bed. It could clog your drain pipe or dip tube. Good luck with it.
 
You will get some galvanic corrosion between the two metals. SS and aluminum are not close on the galvanic chart. While it may be okay for a couple of brews, it would be worth it to get a SS grate to go with the SS bolts.
 
You will get some galvanic corrosion between the two metals. SS and aluminum are not close on the galvanic chart. While it may be okay for a couple of brews, it would be worth it to get a SS grate to go with the SS bolts.

That is a nice thought but I'd rather keep this cheep and simple for the time being. On the other hand I wouldn't mind purchasing different bolts if there is another type of metal that would be better suited to be in contact with the aluminum grate. For instance I almost purchased galvanized aluminum bolts but I wasn't sure what galvanized meant. It sounded like some sort of chemical coating that I might not want in my beer.
 
de5m0mike said:
That is a nice thought but I'd rather keep this cheep and simple for the time being. On the other hand I wouldn't mind purchasing different bolts if there is another type of metal that would be better suited to be in contact with the aluminum grate. For instance I almost purchased galvanized aluminum bolts but I wasn't sure what galvanized meant. It sounded like some sort of chemical coating that I might not want in my beer.

Galvanizing is just adding a thin layer of metal (usually zinc) to the base metal (usually iron) to prevent corrosion of the base metal.

I seem to recall there were some concerns with zinc in wort, but I may be mistaken.
 
What is your brew pot made from? Is it aluminum or stainless steel?? If the pot is stainless steel then you could put some holes into something like this and use it instead of the aluminum screen/sheet you have.
 
Yeah, my pot is aluminum, which is why I went with the aluminum screen route. It's technically a pizza screen too, but it only cost me $4... plus a couple bucks for the screws.

I'm a little nervous about buying something online because there is no guarantee it will actually fit in my pot which has about a 12.25 inch diameter. I found that even though the tray may be advertised as 12 inches, that it probably does not account for the lip around the edge. It's actually over 12 inches and won't fit in the pot and I thought the 10 inch versions are too small. Of all the stores I looked at, including bed bath and beyond, this was the only thing I could find that had a good fit inside my pot.
 
You could try getting some long aluminum pop rivets, and use washers to get it built up. Or see what the hardware store has for aluminum machine bolts. Brass would probably be a better second choice than stainless steel...
 
I checked and called around to the local hardware stores and haven't been able to find aluminum Machine Bolts. I may have to explore the brass route.
 
The standoff could work, but he'll still need a way to secure it to the screen...

Maybe check with a machine shop and see if they can weld some short pieces of round aluminum stock to the screen edges. They might have something to use in the center too, for extra support. Just make sure it's an alloy that won't be an issue in making wort (tell them what it's for so they can use the correct allow)... Hell, you might even be able to get them to fabricate something for you for being able to try some of the first batch you make with the new hardware... :D :rockin:
 
You just reminded me that my cousin works at a machine shop. And he use to home brew. Don't know why I didn't think about that before. I called him and he is going to make me some little legs out of aluminum bar. I'll post new pics once I get it sorted.
 
You just reminded me that my cousin works at a machine shop. And he use to home brew. Don't know why I didn't think about that before. I called him and he is going to make me some little legs out of aluminum bar. I'll post new pics once I get it sorted.

Much better solution!
 
See what happens when enough home brewers get together on helping another with an 'issue'?? :D :rockin:

Hope that he's going to drill and tap them for you. Or somehow get them to secure to the screen... Or maybe he'll be able to weld them to the screen for you... :D
 
You're overthinking it. Keep it dry when you're not using it and it shouldn't be a problem. If it really does bother, you just use some silicone to keep them apart. Washers or o-rings would both be effective.

Corrosion doesn't happen instantly and it needs an electrolyte (often water) to work through. The short time you are using it during brewing should be fine.
 
You're overthinking it. Keep it dry when you're not using it and it shouldn't be a problem. If it really does bother, you just use some silicone to keep them apart. Washers or o-rings would both be effective.

Corrosion doesn't happen instantly and it needs an electrolyte (often water) to work through. The short time you are using it during brewing should be fine.

True, but its kind of fun to have custom made parts too.:)
 
You could use nylon washers instead of (or in addition to) the SS washers. If you are worried about nylon, you can get some sort of silicon cookware and cut insulators out of it. I'm thinking that it will be a long time before galvanic corrosion would be a problem, though.

Edit: Note to self - Always read the whole thread before replying.
 
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