White powder scale on stack

[mspina14]

I have a Mason 2X4 with raised flues that I used for the first time last season.

Since the end of the season, I've noticed white scale-like deposit forming on outside of the stack, which is galvanized:

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Can anyone tell me what this is (and should I do something about it)? :confused:

Thanks

Mark

[markcasper]

It is the precurser of corrosion, soon it will turn into rust. You can paint with linseed oil, but that will just prolong the obvious but it will help delay the rust. Eventually it will rust through, the only real solution is a stainless steel stack. The heat burns the galvanized off and then it starts rusting. You can expect a galvanized stack to last at the most....10 years.

[whity]

It's the Zinc coating flaking off. When galvanized metal gets to hot, this is the result. IMO I would sand it off so it doesn't fall in your sap. You can either leave it untreated metal or like Markcasper said coat it with Linseed oil. Or paint with high temp paint. You can get 1800* paint

[maple flats]

My galvanized stack lasted 12 years, then it had to be replaced. I went SS. I suggest you wire brush it off, then paint it with very high temp rated paint or just leave it. Plan to get SS in 8-10, maybe 12 years. SS should then last a very long time.
The life span for a stack on an arch depends largely on the gauge of the metal. I don't know what gauge comes with a Mason arch, but Bill could answer that. My Grimm arch 2001 vintage was likely 20 Ga (my guess). Keeping the stack dry (and clean) between seasons helps it last longer.

[mspina14]

Thanks guys.

Anyone have a high temp paint that they have used on their galvanized stack that they can recommend?

Is it best to use a spray paint from a can or paint that is applied by a brush? Does it need any kind of primer?

Mark

[Zucker Lager]

Thanks guys.

Anyone have a high temp paint that they have used on their galvanized stack that they can recommend?

Is it best to use a spray paint from a can or paint that is applied by a brush? Does it need any kind of primer?

Mark
Hey Mark:
I used the Rustoleum ultra high heat black on my stack and its holding up well. I also used the heavy duty seamless pipe for my little arch and so far that has held up really well compared to the thin galvanized seamed stuff. $$$$$ but works Jay
https://www.northlineexpress.com/6-x-48-heatfab-single-wall-black-stovepipe-2608b-5184.html?utm_source=googlepepla&utm_medium=adwords&id=353788010092&gclid=EAIaIQobChMItOqas86s1gIVEKppCh0Ozw0nEAQYAiAB EgIpp_D_BwE

This is just a link so you can see what I"m talking about but check your big box stores for this amerivent product its much cheaper Jay

[mspina14]

Thanks Jay.

As you can see in the photo below, I used a stainless steel, double walled stove pipe where the pipe exits the shack through the roof.

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Clearly, stainless steel is the permanent solution. But I've only used the evaporator and stack for one year. So I don't want to chuck the stack and have to buy a new stainless steel one which I'm sure is not cheap to have fabricated.

I will sand the stack down and paint it black with high temp paint. Hopefully that will keep the stack functional for 5-10 years. After that, I'll have Bill Mason make me a stainless steel one.

Mark