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Will drywall mud spots mess with epoxy adhesion?

V-10 Killer

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Midland, MI
I acid washed AND diamond ground my floor last year prepping for epoxy, but it got cold too fast and I couldn't do it. I'll be able to do it any time after now, but I've already got spots of dropped mud from drywalling on the floor. Can I just scrape that up and mop the floor one more time, or will I need to do more. I don't really want to take the chance of messing up the drywall by washing down the whole floor again.

Thanks :)
 
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SC-Eric

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Most drywall mud is acrylic based... In general, acrylics have very low adhesion compared to epoxy. So, the good news is that it should be easy to get up... the bad news is that the cheaper acrylics used in drywall mud won't take the moisture that you will trap with the (I'm assuming) good quality epoxy.

I'd try to get it up with a wire brush... ie... mechanically as opposed to wet...
 

Dave88LX

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Ugh, drywall mud. I don't envy you. I have the same thing to do here shortly, once I get the floor epoxied.
 
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rjy86

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Drywall Mud On Your Floor Is No Big Deal Just Scrape It Up ,and If Your Using A Dark Color Epoxy It Will Cover No Problem But If You Are Worried About It Drywall Mud Is Water Soluble So You Can Just Mop The Floor And It Will Come Up ,if There Was Hot Mud (quick Setting Joint Compound) Used You May Have To Mix A Small Amount Of Muratic Acid With The Water. It Doesnt Take Alot ,That Stuff Will Eat Through Metal, So Be Carefull With It .I Have Been Drywalling For 16 Years And We Drop Mud Everywhere Especially The New Guys We Just Scrape The Floors When We Are Done And Ive Seen Them Concrete Stain The Floors After We Are Done And All They Do For Prep Is Sweep And A Light Mopping. If Your Worried About What Will Happen Just Test A Spot ,throw Some Of The Epoxy Or Whatever Floor Covering Your Going To Use Down Over A Scraped Spot Of Drywall And See How It Looks. Hope That Helps.....roger
 
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SC-Eric

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Drywall Mud On Your Floor Is No Big Deal Just Scrape It Up ,and If Your Using A Dark Color Epoxy It Will Cover No Problem But If You Are Worried About It Drywall Mud Is Water Soluble So You Can Just Mop The Floor And It Will Come Up ,if There Was Hot Mud (quick Setting Joint Compound) Used You May Have To Mix A Small Amount Of Muratic Acid With The Water. It Doesnt Take Alot ,That Stuff Will Eat Through Metal, So Be Carefull With It .I Have Been Drywalling For 16 Years And We Drop Mud Everywhere Especially The New Guys We Just Scrape The Floors When We Are Done And Ive Seen Them Concrete Stain The Floors After We Are Done And All They Do For Prep Is Sweep And A Light Mopping. If Your Worried About What Will Happen Just Test A Spot ,throw Some Of The Epoxy Or Whatever Floor Covering Your Going To Use Down Over A Scraped Spot Of Drywall And See How It Looks. Hope That Helps.....roger

I was kind of hoping someone would post this. It gives me a chance to change the way people think about their projects. You've got to ask the right questions... This is not about coverage. This is about adhesion. It will make no difference to you whether the dark epoxy covered up the drywall mud if the epoxy delaminates in that area. Right? This is not about how it looks... but... if it sticks! Next, concrete stain is either acrylic based or acid stain that contains muriatic acid. I'll get to the relevance of that at the end of the post... For now... read on...

I love to use Scotch Tape. When you think about it, it's pretty cool isn't it? We can wrap Christmas presents with it... AND... when I screw up I can peel it back off carefully and put a new piece of tape on.

On the other hand, when I really want to hold something down... it's Duct tape all the way... I mean, how many of you don't have a roll or two laying around. It's awesome stuff... and... if you use it to wrap presents you can forget about peeling it back off if you make a mistake because it sticks so well to the paper.

Now, of course... I'm making a point.

Acrylics are like Scotch tape. They have some adhesion but are WAY weaker than epoxies (in general). And, epoxies are more like Duct tape... a little harder to apply and ALOT more adhesion.

So, how can I reposition duct tape on a Christmas present if I were to mess up... Seems impossible.. right? Actually... no... not if you first put scotch tape on the present and put Duct tape OVER the scotch tape. When you try to peel the duct tape off, the scotch tape underneath will lose it's bond first and peel off of the paper.

If you are simply going to put an acrylic on the floor that has a similar bond strength to that of dry wall mud then there is not point to spending much time on it... you're just going to put scotch tape on top of scotch tape.

However, if you are going to spend money on duct tape, don't bother putting it on top of the scotch tape!
 
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