Apply thin layer. Sand, Apply new thin layer. Sand. Possibly repeat.

Paint,

PS You'll likely need to put some of the stuff from the can over and adjacent to the metal bead that forms the corner. Sand, paint.

I presume you have tools: one or two joint knives of appropriate width?

Oooh, thanks, everyone!! I will look around for a joint knife, I bet we probably have one, somewhere.

Thanks!!

I am sure You can do it! Just as said above: thin layer, when dry (next day), sand it smooth, apply another layer and repeat everything. Sometimes the air bubble will create, just repeat everything until everything looks smooth.

"Just as said above..." And now repeated? lol

But it's helpful that J Sk said to wait a day - I don't know stuff like that!

I haven't even searched the garage yet for the scrapey thing. But, now I have hope!

For future reference, it looks like you have plaster walls and that one of the top coats came off. You can patch with regular drywall mud or the patching plaster but you have to apply a bonding agent to the old plaster first in order to ensure that the patch doesn't come off later. For small jobs you can mix regular wood glue with water 1:1 ratio. Paint this mix on and apply the patching compound after the glue has dried or is tacky. For bigger jobs get a can of Plaster Weld.

Thanks, HU- ... 2230, I haven't done it yet! Oooh I take too long to do things. The To Do list is something fearsome. At any rate, I appreciate this comment very much.

You can consider using Bondo (autobody filler) to fill in that hole / gouge. My husband has rebuilt cars, including using Bondo to fill in dents. He used Bondo, a few years ago, to repair large cracks around our staircase and entraceway drywall in our 30 year old home; it came out great!! It still looks great years later. When we had our kitchen renovated a few years ago, our carpenter had a lengthy discussion with us, how he loves to use Bondo to repair large gouges and cracks in drywall. Best of luck in repairing your wall.

I just wanted to thank people again for all the good information!!

We were having people over, so I finally got off my duff ... well, halfway off of it anyway.

I am only about a third of the way done - but it already looks much better. Even though the goo isn't "white," which somehow I had assumed. It is sort of an off-white. (But everyone else probably knew that.)

I diluted some Elmers and I used little brushes instead of the joint knives - which it turns out, we have already - because I was worried about being able to control it. I went over the edges, because I thought that would help the new stuff stick to the old - and, I figured, I'm going to sand anyway, so it seemed low risk. Then I let that glue layer (first pic) dry overnight.

As for the plaster-y goo, I think I could have put a thicker layer if I'd used a joint knife, but, I don't mind doing a few coats. I will probably get around to the second coat some time around the holidays, when people come over again.

Is there a limit to how thick of a layer to put? There is a ways to go still - it's hard to see in the photo.

I think the toughest part was mixing the goo with a chopstick - that took a few minutes.

It was actually pretty fun. I think next I will try to learn about fixing baseboards. (The one in the pic isn't even the worst one ... ) (Actually, maybe those are goners and I just need new ones.) I gather I need some type of prying implement. No matter, I'll do a search here. : ) Or maybe I will look into re-painting first. I guess I might as well. It is like that story/proverb - if I make a clean spot, then who knows where I might end up.

Without the help from people here though, I'd probably have just put a plant in front of it. So, thank you.

If you're referring to how thick you can put on the plaster patch stuff, you can do about 1/8-3/16" at a time. Any thicker and it takes too long to dry and is prone to crack. If you have large areas that require 1/4" thick or more patching, consider using hot mud (e.g., EZ Sand), which dries quicker and won't crack.