Plastering outside corner on chimney advice needed

[kelt65]

I'm going to need to replaster a side of this fireplace chimney after ripping out the useless closet that was attached to it (and made the room look silly). The problem is the outside corner there .. I'm thinking I could screw a 2x4 into the plastered side (the front) to guide the corner? It seems like the dried plaster would break off when I remove it, I suppose I could use wax paper between the wood and the wet plaster? I don't think I want to deal with a corner bead ... wouldn't I have to remove an inch or so of plaster on the front to do that? Any ideas?

[img=left]https://lh5.googleusercontent.com/-wEcbObU4Dj8/VEvQonPrXKI/AAAAAAAABK0/AigVrORDuOU/w611-h814-no/20141025_113222_Sycamore%2BPl.jpg[/img]

[Casey]

Sharp outside corners with no reinforcement are really weak, even if you can get the plaster to cure before it simply dries out (flash-dry). This is why a wood molding was used anywhere there would be traffic. Either the earlier inset/flush bead, or the victorian-era 3/4 turning ( like a spindle with 1/4 of the diameter excised).
The proper metal corner bead to use here is this type. You order it based on how thick you want the finished plaster to be on the brick.
http://www.corneranglebead.com/corner-b ... -bead.html
Yeah, you do have to remove more plaster from the chimney; that's life.
Casey

[Mick_VT]

I might install a wood corner of some kind. But really a metal corner would not be too hard, just use a power tool to cut a line down and remove just enough of the old plaster

[Neighmond]

Sombreuil has it exactly-all the places I lived with plaster walls usually have wood outside corners to keep it from damage.

[Texas_Ranger]

In Austria there were a few approaches to this. Exterior corners were usually rounded or chamfered instead of sharp, the radius depending on taste and style. In high-traffic areas such as stairways, the rounded corners were reinforced with some kind of coarse cloth applied like wallpaper, then spackled and painted over. In even higher-traffic areas, steel corner beading (and not modern flimsy stuff, think solid steel L angle!) or metal corner "posts" were used. The L braces are flush with the plaster, the poles were installed using spacers, like a stair handrail. Those poles were usually ornate brass.

Personally I'd probably round over the corner using maybe a 1/4" or 3/8" radius and call it a day. I don't like modern corner beading, it looks wrong in old houses and it's awful to work with, all sharp edges to cut yourself on!

A while ago I painstakingly restored the original rounded corners in a friend's apartment - only to find ou later that her Polish helpers slapped corner bead back on!