Arris

[Gower]

What is the perceived wisdom regarding the arris on finished work.
Should it be removed? If so, by what amount. The piece I am just finishing, is a piano stool in American White Oak. Comments welcomed.

Cheers,
Gower

[Sgian Dubh]

Jul 5, 2008 20:05:01 GMT Gower said:

What is the perceived wisdom regarding the arris on finished work.
Should it be removed? If so, by what amount. The piece I am just finishing, is a piano stool in American White Oak. Comments welcomed.

Cheers,
Gower

A sharp arris has three negative attributes I can think of off the top of my head.

• It's fragile meaning the slightest knock leaves a scar. A softer round is less liable to scarring and other damage.
  

• The user of the piece of furniture will find the sharp edges sharp to touch.
  

• Finally polish doesn't flow well around a sharp arris. Due to the surface tension of the polish whilst still in its liquid form it crawls away from sharp edges. This leads to thinning of the polish at the corner. In use the polish will fail at the sharp corners first of all and flake away: this applies in particular to film forming polishes such as pre-cat lacquer, varnish and shellac. A rounded edge (softened arris) helps the polish flow round the corner meaning a more consistent polish film thickness.

How much you round off the arris depends on a number of factors; the design, the tasks the furniture must do successfully, the polish type, user preferences, etc. At a minimum I create something like a 1.5 mm radius round using a bit of 150 grit paper on a sanding block. With this being the minimum rounding over, the maximum roundover could be almost any radius depending on the job and the style of the piece. And there's more to rounding off edges than just swiping away with a bit of sandpaper. It's what you do at corners where two edges meet that is one way of separating the careless hacks from those with a strong sense of attention to detail. Corners need to be worked with the sandpaper by sweeping around them to eliminate ugly angular faceted intersections highlighted by the polish applied later. Slainte

[Gower]

Thanks Sgian for a most informative reply. I'll act accordingly.

Gower