I live in a 1899 house in St. Louis. The style is of a Richardsonian Romanesque but a little plainer than early forms.

We have these bull nose treatments throughout the house. In most locations they have been either removed or filled in with mud. I would like to repair them in my office where they are still intact. The run from the floor, up the knee wall and onto the sloped ceiling.

Does this style has a name?

Any tips on how to repair?

I vaguely recall a TOH episode where they had something similar and the plasterer made a custom trowel to cut the groves.

About 270° of the round dowel is exposed, so it is not a simple angle on the inside edge. A trowel would have to be rounded out to match the bull nose profile.

The round part is a wooden dowel with a plaster skim coat. In most areas, just the wall edge is damaged, I think that will be easy to repair as I only have to sand down the angle. But in other areas there are chips all the way down to the dowel. These will have to be re-built. Thanks in advance.

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  • I do not see bull noose, I see a quarter round and half round
    – Traveler
    Commented Jan 23, 2023 at 23:59
  • yeah it looks a lot like half round, are you certain that to does more than 180 degrees of curve?
    – Jasen
    Commented Jan 24, 2023 at 3:32
  • Hard to capture the angles in the photos due to shadows. The angle from the wall back to the rounded edge is about 45 degrees. That surface is flat. It joins the round edge further back than 180 degrees. I've not measured but estimate about 3/4 of the round edge is exposed. Commented Jan 24, 2023 at 19:17

1 Answer 1


Whatever the actual shape (quarter-round, half-round or three-quarter-round) or name, I think you've got it right on the repair side.

You'll have to take a flat edge trowel and cut out a matching slot in it so you can trowel plaster to match the existing curves.

Since you want a perfect circle, the easiest thing would be to drill a hole in the trowel of the correct diameter. However, drilling a hole where the center point is right at the edge of the material being drilled through is extremely difficult. Therefore, I'd suggest:

  • Start with a big trowel
  • Draw a line all the way across the working edge of the trowel, about 1/4" up from the edge.
  • Center punch on this line and near one side of the trowel to make a starting point for your drill bit.
  • Drill the hole the diameter that matches your round over.
  • Cut the excess trowel off along the line.
  • Gently sand all the cut edges to just ease them and to remove any sharp burrs.

You will now have a half-circle centered along the edge of your trowel.

To do the repair work, put some plaster on the wall and work it to shape with the trowel working from one face of the wall, then work from the other face. If you're left with a little bit of a ridge from dragging the trowel along the two faces, you can smooth that down while the plaster is still wet, or, if you can't work it without ruining the curve, wait until it's dry and gently sand the ridge off.

If you do, in fact, have 270° of exposed edge (I think you do, based on your statement and the appearance in the pics, but there is some question as noted in comments on your question), there is no way you'll be able to make a tool that will work this in one single pass.

If it's actually less than 270°, you might be able to make a single-pass trowel by finding the center of your trowel, drilling your hole there, then cutting near the diagonals to make a 90° corner in the trowel's metal. Odds are good you're going to go through a few trowels trying to get this just right, so you may want to plan ahead.

  • It is more than 180° for sure. I am consider a three step approach. 1) Make a jig with two boards at right angles. I will use this to fix the edge where the wall ends. In some locations that is badly chipped back so you no longer have a crisp line. 2) Trowel the angle portion. 3) Skim coat the round portion with 2 passes, one on each side. On the 3rd floor, I have a room with 1 large dormer and 2 smaller ones. The shadows these details create look great, especially higher up where they are in better shape. Commented Jan 24, 2023 at 19:29

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