I don't know that I'd attempt to skim coat with a setting compound, thinned down premixed joint compound makes the job a lot easier. I'd scrape if needed and apply more mud to hide those 'streaks'.
Why are the gaps forming?
Background: I pried hardboard off the walls, scraped the construction adhesive to take down the high spots but didn't scrape all of it off, and sealed the damaged paper with 2 coats of Gardz.
I had some deeper damaged spots to fill (not shown) and some mismatched pieces that I wanted to level up with a thick layer of joint compound, so I bought 90 minute setting compound for that and pre-mixed topping compound that I'll finish skimming with for easier sanding.
Much of the corner tape peeled off when I was scraping the adhesive (which tended to be thickest in the corners) so I'm retaping the corners and using the hot mud for that, in part to use it up and also because I kinda like doing things the hard way.
I also thought I might use it for a first thin skim coat to start leveling out the squiggles of damaged paper and adhesive. My hope was that the hot mud might stick to the adhesive better (warn me know if this is never going to work and I have to start over by scraping off ALL the adhesive!)
After finishing a couple of corners, I didn't think I had enough mud left to finish the next corner reliably, so I grabbed the 12" knife and spread the remainder on a few square feet of the wall. I didn't time how long since I'd mixed it, so let's guess somewhere between 40 and 60 minutes. I couldn't see actual dried chunks in the mud, but got a lot of these long voids when smoothing it. My first guess was that they are from bubbles mixed into the stuff as I scraped the excess off the tape joints and slapped it back into the pan (I could see some bubbles in the mud, I think), but now that I go back and look at the wall, there are some little pieces in most of the voids, so maybe there were dry little boogers that were forming around the thinner edges in my pan. Is that right, and is there a trick for dealing with this?
I had some deeper damaged spots to fill (not shown) and some mismatched pieces that I wanted to level up with a thick layer of joint compound, so I bought 90 minute setting compound for that and pre-mixed topping compound that I'll finish skimming with for easier sanding.
Much of the corner tape peeled off when I was scraping the adhesive (which tended to be thickest in the corners) so I'm retaping the corners and using the hot mud for that, in part to use it up and also because I kinda like doing things the hard way.
I also thought I might use it for a first thin skim coat to start leveling out the squiggles of damaged paper and adhesive. My hope was that the hot mud might stick to the adhesive better (warn me know if this is never going to work and I have to start over by scraping off ALL the adhesive!)
After finishing a couple of corners, I didn't think I had enough mud left to finish the next corner reliably, so I grabbed the 12" knife and spread the remainder on a few square feet of the wall. I didn't time how long since I'd mixed it, so let's guess somewhere between 40 and 60 minutes. I couldn't see actual dried chunks in the mud, but got a lot of these long voids when smoothing it. My first guess was that they are from bubbles mixed into the stuff as I scraped the excess off the tape joints and slapped it back into the pan (I could see some bubbles in the mud, I think), but now that I go back and look at the wall, there are some little pieces in most of the voids, so maybe there were dry little boogers that were forming around the thinner edges in my pan. Is that right, and is there a trick for dealing with this?
