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Sanding

Who loves sanding?  Not us!   Probably nobody really loves to sand, which is why this crucial step gets skipped or done with partial effort. Maybe the client won’t notice how sanding between steps has affected the overall decorative finish, but as a professional, you should be able to see and feel the difference. Pierre Finkelstein of Pierre Finkelstein Institue of Decorative Painting Inc. explains more below.

ABOUT

When viewing a surface, especially faux marble or wood, most clients will use their hand to touch the surface before they will appreciate the quality of the paint and design. It’s important for your work to not only resemble a finish but to actually have the same texture.  Sanding is crucial to getting a professional surface.

THE GUIDELINES

UNDER 200 GRIT

  • Sanding scratch coat of plaster
  • Initial sanding of a patch
  • Preparing raw wood
  • Cleaning metal tools

220 GRIT

  • Sanding primer
  • Sanding after first base coat
  • Knocking down medium textures
  • Sanding after shellac
  • finishing a patch job

320 GRIT (320 is the most commonly used grit in our shop)

  • Sanding final base coat for glazing
  • Sanding after first varnish coat
  • Finishing a patch job 

400-600 GRIT

  • Sanding in between fine varnish coats
  • Sanding basecoated profiles for glazing
  • Sanding after first oil basecoat for final basecoat
  • Sanding first steps of lacquer or French polish
  • Sanding final fine texture polishing

800-1200 GRIT

  • Sanding Final steps of lacquer or French polish
  • Sanding final extra fine texture polishing (used wet for additional fine sanding)
  • Sanding other finishes requiring “glass” finish

THINGS TO CONSIDER:

  • Varnish sheen – The higher the desired sheen, calls for a higher grit sandpaper (800-1600 grit)
  • Spraying – For a glass like finish, use a combination of sandpaper going from a higher grit to lower (400-1600 grit)
  • After Sanding – Sanding is a useless step if you don’t dust after (there’s an art and a Dusting Brush for that too)
  • Take pride in sanding, it will separate you from the rest, even if most people don’t notice!

THE SUPPLIES

An electric sanding machine can also be used when knocking down tough, heavy textures (for those under 200 Grit).  It is important to be careful of the “fish eye” marks that can appear with a machine.

A wooden block wrapped with sandpaper or a sponge block is sometimes used when substrates are very cumbersome to knock down.  Also, with a block, a very even distribution of pressure is possible that is difficult with sandpaper.

Soft sanding sponges are very handy on big walls as they tend to distribute an even pressure and are easy on the hand.  When sanding profiles on moldings, soft sponges are the safest way to distribute an even sanding without “burning” the edges.   However, soft sponges can become worn down very fast and lose their grit. Worn sponges, however, can work when wanting to knock down “dust and fuzz” trapped on a dry glaze before varnishing.

Sandpaper is the main way to sand a surface. There are many grits to choose from and paper can be shaped or torn as needed.

THE TECHNIQUE

When training employees, teaching them how to sand and tape is a struggle.  Everyone thinks they know how to do both of those crucial tasks, but do they know how to do it well?

SKILLS NEEDED:

1) Finesse – It’s easy to sand too much or not enough depending on the pressure added to the sandpaper. A foreman should always show an example of how each specific surface should be sanded.

2) Basic ambidextrous capabilities – One hand is sanding while the other is feeling the surface for imperfections, both in a circular motion (wax on wax off).  This is a difficult skill to master.

3) Concentration – It’s important to keep concentration otherwise the sanding will be spotty at best.

4) Systematic ability – It’s important to systematically sand otherwise entire sections can be missed. This is especially important when sanding as a team.

Below is the best way to fold a standard sheet of paper (featured. in the Art of Faux by Pierre Finkelstein).

Folding Sandpaper Step 1
Folding Sandpaper Step 2
CAPTION: Folding Sandpaper Step 3

With this fold, the paper is thick under your hand, which leads to even pressure.  Also, you’ll have 6 sides to flip before the paper has exhausted its life.

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