# Skim coat artifacts



## Chris N (10 mo ago)

Hello. I'm a DIY guy. Right now I'm learning to skim coat, and I'm getting some strange artifacts on the second coat.
I'm using the roller and squeegee trowel method. (Feel free to roll your eyes  )
Mud is USG Green bucket, thinned with roughly 10 oz. water per gallon.
The first coat troweled smooth, and dried smooth.
The second coat troweled smooth, but developed some strange artifacts when it dried.
A new roller cover didn't make any difference.

Any advice or suggestions are appreciated.

Thanks,
Chris


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## hendrix417 (Aug 9, 2018)

another coat, at least...


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## picks drywall (Apr 13, 2021)

did you scrape a spot to test whats going on? is it blistered or powdery? you mite need a sealer over it if its a reaction. any chance there is old enamel paint under there?


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## Chris N (10 mo ago)

Thank you for your assistance, _*hendrix417 *_and _*picks drywall*_.
The walls are old horsehair plaster. I coated them with Larsen Plaster Weld, and let it dry.
It's difficult to see in my photos, so I zoomed in on one. The artifacts are not raised, but similar to small gullies. I scraped a spot now, and the material seems fine.
Also, I was mistaken. Watching closely, I noticed that the artifacts are formed as I trowel/squeegee.
Could this be related to the consistency of my mud? Or the thickness that I roll on?


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## Shelwyn (Apr 10, 2015)

Why dont you buy a smoothing blade / finishing knife? They cost like $60 and you can save yourself a lot of time and effort learning how to smooth by hand.

The squeegee isn't the right tool for the job there are specialized tools you can use instead and they'll leave a better result.

I can't tell what the problem is you're picture look like they were taken using your feet (joke). They're too zoomed in and we can't see the environment or the rest of the wall. I feel like it's a problem with inconsistent pressure /smoothing using a squeegee. Also the mud might have been too hard. 

Since joint compound is always inconsistent telling us you added x amount of water is actually really useless haha.


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## Plaster 101 (Sep 11, 2021)

Chris N said:


> Thank you for your assistance, _*hendrix417 *_and _*picks drywall*_.
> The walls are old horsehair plaster. I coated them with Larsen Plaster Weld, and let it dry.
> It's difficult to see in my photos, so I zoomed in on one. The artifacts are not raised, but similar to small gullies. I scraped a spot now, and the material seems fine.
> Also, I was mistaken. Watching closely, I noticed that the artifacts are formed as I trowel/squeegee.
> Could this be related to the consistency of my mud? Or the thickness that I roll on?


I think your problem is the use of a roller to apply the finish over Plaster - Weld.
The Product is a flexible Film & the dry film is re-actived by moisture & the roller is pulling the film causing your problem.


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## Yunggranmassa (Oct 9, 2021)

Your squeegee sucks bro. Get you a 12" & pan, & go from there. Those rubbery things are for doing knockdown textures, they're not skim blades. I don't care what a soul on this earth has to say otherwise; whether it be any homebuilding show, website or forum, article,  or dahgun'd sticker --- Ain't no skim tool. Ain't no arguing to it neither. Any argument anybody could try to have about it can prove only one thing-- Ain't no Finisher neither

Now goes to say: there's nothing wrong using a roller to apply the mud, it's all about how you roll it, use what's known as a "loop" roller when you do. It carries mud the best, and it washes out. Home Depit sells them in the paint department. On ceilings -- start out far away & just calmy roll the mud towards you, else you'll end up hunkin phat globs of mud off your roller skin into the floor; and pushing the roller away from you flings it in yer eyezzz..... and will make your state of mood, not a very good one. No sir.
Walls-- just start in the middle and push the mud up before coming top down with the roller. Best way to properly load an area with mud so that the coverage is enough to skim. I have done great work skimming by rolling the mud and wiping with a 42" & scraping back into the bucket with a 6", or even just a 14" knife & pan.... but using a spray rig & wiping with a big blade on a box handle is the ways of Jedi.


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## Yunggranmassa (Oct 9, 2021)

Oh yeah, & also some of these "artifacts" look like dead spaces to me. Spots where enough mud wasn't applied on the surface to be able & pull clean sheets


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## endo.alley (8 mo ago)

Might be dry mud sticking to the blade. You need to clean the blade off with a sponge after each pass. You need to fix the bad spots with another coat. When that dries, sand and coat everthing again.


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## hendrix417 (Aug 9, 2018)

2 more skim coats. skim, sand.. skim, sand.. prime with best primer you can find. young is right .. mud pan, 12" knife..


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