Metal finishes for staircases and other home fixtures, as well as automotive finishes, are often available only in gloss, and that may not be what you want. Or you may have chosen a gloss metal finish only to decide later that it is too shiny or bold. You cannot cover glossy paint with flat or matte paint, but you can cut down the gloss of a high-sheen finish. Do this with a liquid deglosser to cut the gloss of the finish followed by a clear matte varnish or topcoat to refine and preserve it.

...
You can use matte varnish or deglosser to cut the shine of a new car paint job.

Step 1

Spread drop cloths around the area to be deglossed or refinished. Cover them with newspapers so that you do not slip on spilled deglossing solvent.

Step 2

Saturate a clean, dry cloth with deglossing solution and rub the surface in a circular motion. Change cloths frequently to prevent removed finish and dirt from adhering to treated surfaces.

Step 3

Brush an even coat of deglosser onto the treated surface if the surface is still too glossy or if the finish has become uneven. Allow the deglosser to dry for 30 minutes.

Step 4

Shake a can of aerosol matte varnish very well. If there is a rattling device inside the can, shake until you no longer hear it.

Step 5

Hold the can of varnish about 4 inches from the treated surface. Spray a fine, even coat of varnish along all parts of the treated surface. Allow the varnish to dry for about 10 minutes. Spray another coat of varnish over it.

Step 6

Allow the second coat of varnish to dry for three hours before you handle or use the treated surfaces.