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Why is my hot mud setting so fast?

9.8K views 13 replies 4 participants last post by  Lemkie  
#1 · (Edited)
So let me just start by saying that I've been using this same product (Sheetrock 90, I'm in Canada) for over 5 years at least a few times a year. I'm not a professional mudder by any means but I've used this stuff often enough to know how to use it and to know that it sets in approximately 60 minutes.

Today I started plastering my basement which I recently drywalled. I mixed a batch of this stuff which I just bought yesterday. I mixed it to the same consistency I usually do (peanut butter ish) and started mudding away. Suddenly I realized that this stuff was setting on my hawk. I figured the hour had just flown by and went to clean my tools and bucket. The stuff left in the bucket had also already began to set. I had to scrape it out as it came out in hardened chunks. Now again I realize this stuff sets quickly, but I've mudded with it before as I say and went at least to 80 minutes without that batch becoming as set as this batch.

Anyway I mixed another new batch after cleaning everything and set a timer. About 30 minutes in, the batch started setting just as bad as the first one. I'm at a complete loss here. I even checked the bag thinking maybe I somehow had grabbed some sheetrock 45 by accident, but no it is in fact sheetrock 90.

Short of the company putting the wrong powder in the bag I really don't know what's going on here. I'm wondering if I'm doing something wrong and not realizing it? What would cause 90 minute hot mud to set within 30 minutes? My basement is on the humid side (80 percent at the moment) but I've mudded down there before in another room with Sheetrock 90 without any issues.

Any thoughts?

Thanks!
 
#2 ·
Anything different with your water source.

I don't know the chemistry of hot mud, but salt (potassium or calcium chloride) acts as an accelerant in cement/concrete, ... guessing it might accelerate hot mud mixture also.

Is a water softner involved...?
 
#5 ·
Don't know... never happened to me... don't think additives can settle out or u or down in a bag.... don't think so...

but possibly production lines do screw once in awhile.
Yes it seems very odd. I'll pick up another bag from a different store tomorrow and see how that goes. I do remember this bag I have currently was one of the last few bags at the bottom of a skid but I got it at Home Depot and I would think they sell this stuff fairly frequently. Definitely often enough that the bag wouldn't have been sitting there's for years and years or anything like that
 
#8 ·
How are you mixing your mud?

Over mixing or taking to long to mix can cause it to set prematurely.

Do you let the mud rest for at least one minute (longer in colder conditions) before remixing and getting the hot mud to the desired consistency?

Where are you located?
 

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#9 ·
I use a squirrel cage mixer to mix my mud, using my drill on low speed. I mix until the mud is uniform then I stop.

I'll usually add extra water or mix while I'm mixing if it's too thick or thin. I've always done it like this but is that not the way to go?

I am in Northern Ontario
 
#12 ·
I bought a new bag of Sheetrock 90 today, mixed it up and used it at usual without any issues. I mudded for a little over an hour and even then it still hadn't set as bad as the batches from yesterday. I used the same water and did everything the same. I don't know what to say other than a bad batch of product but I hate blaming the company just like that. In either case it's nice to know I'm not going crazy haha.