Spackled deep holes about two years ago and overfilled the holes till the spackle made a bump on the wall. Holes were in a tough spot high up in a two story open room so the job didn't get finished. Now I am trying to paint those second story walls and the spackle bumps will not sand down. They just start to get shiny. Should I try wetting them? or do I need to dig the spackle out of the wall and start over?

Hi all, DIYer here. This is my first skim coat attempt and I've read all of the how-tos and watched all of the YouTube videos. I realize this is 70% skill and 30% knowledge. I'm doing a small bathroom. The paint job was peeling off so I was able to easily remove all of the paint from the room, but ended up with a lot of torn drywall paper. I sealed the walls with Roman Rx-35 PRO-999 and just put up the first skim coat layer. I used USG All Purpose "green top" bucket, thinned down to what I think is "yogurt like", though it seemed to take a lot of water. I mixed it with a drill and a ribbon paint mixer. Here's what I am struggling with: [list] [*]I tried the paint roller trick but it just didn't work out for me. For starters, a 9" roller was too big to do most of this bathroom. I tried a smaller roller with 3/4" nap but that didn't work either. [*]I seemed to have better results just knifing the mud on as I went. I used a 12" taping knife. [*]What I am not understanding is how much mud I should be leaving on the wall? I realize if I were filling a texture, the mud would fill the gaps. In this case, I'm just trying to hide the indentations where the drywall paper is missing among some other wall imperfections. Several videos state the layer is around 1/8" thick or so, but as I'm smoothing out the mud, I frequently end up feathering out the mud thin enough that I can see the bare drywall. In many of the videos I've watched, I can hear scraping on the leading [*]I know this will likely take 2-3 skim coats, but what I am looking for are "milestones" for those coats. [*]When I smooth out coats, I frequently get what look like tears in the mud, but it isn't something dragging... It often looks like peeled drywall paper but isn't. Should I worry about these? If I continue to smooth out and press harder, they go away but then I end up taking off more mud than intended.. or so I think. [*]I think one hurdle here is that as I am pulling my knife, my walls aren't exactly flat. [*]So right now, my first coat is up and drying, but I have a lot of lines to scrape off or sand out. I couldn't seem to find a pattern to keep pressure on one side of the knife and lift the other because I was constantly changing directions. Given its a bathroom, there's the door, a linen closet door, and a shower tub to work around. Once I cleaned up the mud in one direction, as soon as I switch directions I would mess up what previously looked good. I would have maybe 14-16" between the corner and a door frame, and taking the knife from the floor up failed because this piece of drywall wasn't square and my knife wouldn't keep on the mud no matter how flat I had it to the wall... and then the corners were awful. So I would pull from the corner to the door frame, every 10" from the floor up, overlapping slightly. [*]Was I expecting too much out of this first coat? [*]Should I scrape off edges and do a light pole sand before the second skim coat? [/list]