Portable substrate etching apparatus and process

A portable substrate etching apparatus, which comprises:

• (a) a transparent casing having an opening at one end to be positioned against the substrate,
• (b) a manually directable sandblasting nozzle in said casing,
• (c) means for supplying sandblasting grit entrained in a pressurized fluid to said sandblasting nozzle,
• (d) means for removing spent grit from said casing by gravity flow, comprising a funnel-shaped bottom portion of said casing, and
• (e) means, independent of said spent grit removing means, for removing the fluid at a rate slightly in excess of the rate it enters said casing through said nozzle.

A portable substrate etching apparatus, which comprises:

• (a) a transparent casing having an opening at one end to be positioned against the substrate,
• (b) a manually directable sandblasting nozzle in said casing,
• (c) means for supplying sandblasting grit entrained in a pressurized fluid to said sandblasting nozzle, and
• (d) a resilient hand insertion means at another end of said casing remote from the one end.

A portable substrate etching apparatus, which comprises:

• (a) a transparent casing having an opening at one end to be positioned against the substrate,
• (b) a manually directable sandblasting nozzle in said casing,
• (c) means for supplying sandblasting grit entrained in a pressurized fluid to said sandblasting nozzle, and
• (d) a protective screen having openings which allow visual observation of the substrate through said screen and allow grit particles to pass through said screen, said screen further preventing ricocheting grit particles from the substrate from contacting said casing directly, said screen surrounding at least a portion of the inside of said casing.

A method for etching designs in a substrate, which comprises:

• (a) masking the substrate except where the design is to be formed,
• (b) placing a transparent housing including a manually directable sandblasting nozzle and an opening over a portion of the substrate, with the opening against the substrate,
• (c) directing the nozzle at the exposed areas of the portion of the substrate to sandblast them,
• (d) moving the transparent housing to cover another portion of the substrate including an exposed area forming another portion of the design,
• (e) directing the nozzle at the exposed area of the other portion of the substrate to sandblast it,
• (f) withdrawing air from the transparent housing at a rate slightly in excess of a rate air enters the housing through the sandblasting nozzle, and
• (g) removing spent sandblasting grit from the housing and recycling it to the sandblasting nozzle.

Apparatus for etching a substrate, which comprises:

• (a) a casing for enclosing at least a surface to be etched of the substrate, said casing including at least a transparent portion for viewing the surface,
• (b) a manually directable sandblasting nozzle positioned inside said casing,
• (c) means for delivering a stream of compressed air containing sandblasting grit particles to said nozzle, and
• (d) a protective screen having openings which allow visual observation of the substrate through said screen and the transparent portion of said casing and allow grit particles to pass through said screen, said screen preventing ricocheting grit particles from the substrate from contacting the transparent portion of said casing directly, said screen being positioned between at least the surface of the substrate and the transparent portion of said casing.