Polishing plaster?

Polishing plaster is a process of cross-trowelling of the plaster. Depending upon the actual finish to the plaster, it isn't always desirable, as the plaster can become too smooth and too polished.
As I understand it, you commence like ever at the top of the wall, usually at the end of the plaster setting stage and apply some water to the trowel and moving from left to right (assume right handed) hold the trowel tight to the wall so that the trowel's left edge touches the wall, leaving about 0.5mm space between the right edge of the trowel and the wall and walk the length of the wall maintaining a horizontal movement and contact with the wall throughout. Once you have gone along the length, remove the trowel and do the reverse at a lower level and ensure that the lower trowelling covers the upper trowelling. Continue to apply water to the trowel and continue to trowel down.
Once you've done the wall for the whole of it's height, you can repeat the process and 'polish'. The more you do it the more it shines ....too much though and no paint will adhere to it as there is no mechanical key unto which the paint or other substance can attach itself.

DoL
April 2009