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Coleman extreme 70qt mash tun questions

I’m in the process of taking this cooler and making a mash tun. I went and got all the parts and have a few questions.

I got the 3/4 inch washers, stainless and zinc, but they sure look the same. How can I tell if the one is really stainless?

Also, the stainless washer does not fit over the nipple like the zinc one, do I have to use stainless washers or can I just use some hard plastic ones on the inside instead? I have no way to increase the size of the hole on the stainless.\

I’m on my way to all grain… :slight_smile:

Hey GarretD,
Magnet –
Typically ss washers you buy from a hardware store would be made from a 300 series of ss which would typically be very, very weak magneticly but due to some manufacturing processes can make them more magnetic. So a magnet test can be misleading. The zinc one will be magnetic for sure, so a weak magnet would stick easier to zinc plated washer than a ss washer. Maybe try a vinyl refrigerator magnet, they tend to be weak.

Visual –
Zinc plating can have a bluish hint to it or even yellow, maybe a very, very slight mottled iridescent in the right light and reflection. SS will be more dull grey.

Corrosion –
Use a file and file down a edge to get past the zinc plating. Place the washer in a salt solution for half a day, as long as you filed past a coating, the inner steel will start to have rust on it. SS should not look to be corroded as long as you didn’t transfer and embed steel particles from the file into the ss.

I would go to the effort to be sure to use ss on the inside. As far as hard plastic goes, it depends on the plastic. What seems like a stiff, resilient plastic at room temp can become soft and yielding at mash temps.

Why not make sure and use ss washers in and out? IIRC I had to tweak the inside diameter of the washer very slightly with a file or maybe it was the thread on the nipple. ???

I hope this was helpful. Good Luck!!
VK

[quote=“Brew On”]Hey GarretD,
Magnet –
Typically ss washers you buy from a hardware store would be made from a 300 series of ss which would typically be very, very weak magneticly but due to some manufacturing processes can make them more magnetic. So a magnet test can be misleading. The zinc one will be magnetic for sure, so a weak magnet would stick easier to zinc plated washer than a ss washer. Maybe try a vinyl refrigerator magnet, they tend to be weak.

Visual –
Zinc plating can have a bluish hint to it or even yellow, maybe a very, very slight mottled iridescent in the right light and reflection. SS will be more dull grey.

Corrosion –
Use a file and file down a edge to get past the zinc plating. Place the washer in a salt solution for half a day, as long as you filed past a coating, the inner steel will start to have rust on it. SS should not look to be corroded as long as you didn’t transfer and embed steel particles from the file into the ss.

I would go to the effort to be sure to use ss on the inside. As far as hard plastic goes, it depends on the plastic. What seems like a stiff, resilient plastic at room temp can become soft and yielding at mash temps.

Why not make sure and use ss washers in and out? IIRC I had to tweak the inside diameter of the washer very slightly with a file or maybe it was the thread on the nipple. ???

I hope this was helpful. Good Luck!!
VK[/quote]

Thanks! The magnet trick is spot on as the zinc one stuck to it like glue and the SS on did not at all. I guess I’ll have to find a way to increase the hole size.

I am a bit confused though…I guess I assumed the SS washer is just a coated washer…so if I increase the hole it will expose what the real washer is. Are SS washers solid SS?

Yes, the ss washer will be solid thru and thru. So filing the inside diameter will be okay but not easy without a fine or medium curved file, not a flat one.

Is the amount of interference between the nipple threads and the washer just slight? You could remove some of the crest (top edge) of the thread on the nipple as an option but you wouldn’t want to remove too much.

You could also do the following to enlarge the hole in the washer but will need vice, drill and an abrasive bit (see below). Clamp the washer in the vice so the hole is accessible and remove even amounts all around the inside until it just fits .

And yet another suggestion. The physical size tolerence on standard binned washers can be pretty big. If you go to a good hrdwr store that sells individual washers maybe you can cherry pick one that has the inner diameter on the big size and fits over the nipple threads. Take the nipple with you and try them out.

Good Luck!

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