Taping a painted wall?

Adding a partition wall in a finished room. New wall meets finished wall, so need to mud & tape the corner.
How do you do this? With latex paint on existing wall, mud won't stick well. Sanding latex isn't a clean solution, and anyway, using abrasives to get down to the sheet rock paper risks going through it.
Is this just a matter of patience and lots of sandpaper? Or is there a better solution?
Suggestions?
Thanks,
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DaveC wrote:

Where did you get that idea? It's done all the time and sticks just fine. Taping compound will stick to glass.

If it's a gloss paint (rather unlikely on a wall), and you feel you must do something, scuff it up with sandpaper. You're not "sanding" it, just scuffing it up to give it a little tooth.

Without a doubt you have the most obnoxious tag line I've seen. If you _had_ googled you'd find answers to all of this stuff you've been posting about. Saying you have googled when you haven't is just lazy and an obvious lie.
Obviously this is the last question of yours I'll bother to reply to.
Ta-ta
R
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Never had any problems with mud taking to latex paint. In fact if I have raw gypsum edges that need mud to stick to them, I always paint or prime with latex to make the mud stick. Also after priming with latex one often finds divots or rough spots, adding mud to smooth these out is standard practice.

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DaveC wrote:

Should stick fine. I've never epxperienced taping mud not sticking over latex paint. In fact on several occasions I've skim coated gloss walls with taping mud as a base for spray and that worked fine also. Another way is to lay the tape flat on just the new wall and make it tight, right up to the old wall. In other words don't make a 90 with the tape. Just make it tight to the corner. Problem with that is a hairline crack can occur there due to soem shrinkage and may necessitate a very thin line of caulking be placed in the 90 prior to painting.
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Inside corner or outside corner. Have you considered using a metal corner bead instead of just taping (usually on outside corners).
Try a little more water in your mud. maybe too dry.
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Would imagine you're going to texture the new wall, before you paint it. You going to texture over a freshly painted in corner?
If you can't get the drywall mud right, get the pre-mixed version. You'll need more than one coat of mud, its applied thinly. Lotta guidance both oral and written on drywall applications.
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Just tape into it. The only adjustment that I make with paper joint tape is to not force all of the compound from under the tape on first coat...the latex paint makes it slide out more easily than with fresh gwb.
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Thanks to all for your suggestions.
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