# Unexplained Mystery



## Big Shoe (Jun 16, 2008)

Did a repair Saturday. 3'x5'. Typical mesh, 5 minute mud job. Slam it out...................Not. 

It was one of those weird mud just sits there around the edges and does not set up. :no: Break out the fan and it turned into half an hour or so between coats. I need to keep that heat gun in my truck. 

It happens about 1 out of 20 repairs. Something about the paint? Cold ceiling? Bad water? All of the above? Drives me nuts when that happens. 

Going back this morning to tight skim, fan and sand. Bringing that heat gun too.


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## KAP (Feb 19, 2011)

Too much water?...


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## Sir Mixalot (Jan 6, 2008)

It's the paint and the coolness of the surface. 

I always keep the Milwaukee heat gun in the van. What I like to do on ceiling and wall repairs is heat the surface first before applying the hot mud. Especially if the paint on the existing area has a sheen. :thumbsup:


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## blacktop (Oct 28, 2012)

Enamel paint is a pita!


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## illbuildit.dd (Jan 7, 2015)

I always figure the paint won't sponge the moisture and let it dissipated. I use hairdryers I pick up at yard sales and Irwin clamp the to a ladder on the patch while I do something else


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## Dave in Pa (Oct 10, 2009)

I have done/seen the same thing happen. If it is a "setting type" hot mud, water should not be a issue? 

What I do now is scuff the paint surface with a NEW course, sponge block, seems to help out, cut the surface of the paint to help dry??? BUT once again, it is a chemical type set mix, not a air dry compound???

A heat gun for a few moments will activate it to cure. Some things I just can not figure out!! LOL


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## blacktop (Oct 28, 2012)

I hear applying an oil base primer can help hot mud adhere to a painted surface before patching .. And It can cut the bubbles out to a minimum .


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## CarrPainting (Jun 29, 2010)

I have run into this myself, only with bags of 20... if after 40 minutes it hasnt set, i scrape it off, use hot water, add accellerator to it, and the stuff sets up in about 10 minutes... gauranteed! :thumbsup:


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## Lugnut1968 (Dec 11, 2014)

Glad I am not the only one who has this happen to them. Had been wondering what the heck was going on. Mix 20 minute and at times it was taking 4 hours to dry... Thanks OP for the post and thx to the rest of ya for fixes on it :thumbsup:


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## Sir Mixalot (Jan 6, 2008)

blacktop said:


> I hear applying an oil base primer can help hot mud adhere to a painted surface before patching .. And It can cut the bubbles out to a minimum .


Yep! :thumbup:


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## Lugnut1968 (Dec 11, 2014)

Sir Mixalot said:


> Yep! :thumbup:


That is exactly what I was thinking. Wish they would put some of the Zinsser Cover Stain in a dang spray can though...


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## Sir Mixalot (Jan 6, 2008)

Lugnut1968 said:


> That is exactly what I was thinking. Wish they would put some of the Zinsser Cover Stain in a dang spray can though...


Wishes do come true on ContractorTalk! :laughing:


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## sunkist (Apr 27, 2012)

i use work lights on the tri pod stand to heat up drywall


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## Sir Mixalot (Jan 6, 2008)

blacktop said:


> I hear applying an oil base primer can help hot mud adhere to a painted surface before patching .. And It can cut the bubbles out to a minimum .


The kilz spray can also seals in the dust which helps the mesh tape stick better on drywall repairs too. :whistling


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## Lugnut1968 (Dec 11, 2014)

Sir Mixalot said:


> Wishes do come true on ContractorTalk! :laughing:


Heck yeah!! Now I have to find it in a store around here. For some reason everyone seems to be pulling Zinsser off the shelves


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## Sir Mixalot (Jan 6, 2008)

Lugnut1968 said:


> Heck yeah!! Now I have to find it in a store around here. For some reason everyone seems to be pulling Zinsser off the shelves


I've seen it at Walmart for $14 a can. :thumbsup:


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## hdavis (Feb 14, 2012)

Nobody mentioned having the mix separate out some in the bag...


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## icerock drywall (Aug 16, 2012)

prep first never rush into the patch...or "sometimes" it bites you in the A##


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## Big Shoe (Jun 16, 2008)

KAP said:


> Too much water?...


Nope



Sir Mixalot said:


> It's the paint and the coolness of the surface. I always keep the Milwaukee heat gun in the van. What I like to do on ceiling and wall repairs is heat the surface first before applying the hot mud. Especially if the paint on the existing area has a sheen. :thumbsup:


The insulation was Icynene. cool attic. Funky paint.



Sir Mixalot said:


> I've seen it at Walmart for $14 a can. :thumbsup:


I bought some at PPG. Cover stain is my ''Go To''.



hdavis said:


> Nobody mentioned having the mix separate out some in the bag...


I hear ya.  Same bag day before. Floated out newly painted eggshell walls on a new build. No problems. Rapid fire three coats.......................:blink: Figure that one out. :no:

I think pole sanding with some 80# May have helped ???? Anyhow, I sanded it yesterday morning and got paid. :thumbsup:

Side note: Repaired same ceiling two yrs ago. Same leak. No problem with my 5 min. then. Go figure. :no:


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## mako1 (Sep 1, 2013)

Still have the Zinsser at Ace Hardware here.


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