Method for making an ear plug

Claim 1

A method for forming an earplug for reduction of noise when worn by a user which method comprises the steps of: (a) first placing a fibrous pellet in the ear canal of a user past the second bend and thereafter forming a plastic impression of the ear adjacent to the pellet, and wherein some excess plastic impression is formed which excess is partly shaped by the external ear and which reaches the outer end of the ear canal; (b) trimming the plastic impression to form a generally flat face thereon which trimming removes the external ear portion of the impression; (c) coating the trimmed impression with an external wax coating by dipping, and dipping the impression in a soapy liquid parting agent and thereafter permitting the impression to dry at room temperature and thereby harden on the outer surface; (d) glueing the trimmed impression along with a plurality of similarly obtained impressions to a flask plate at the flat face thereon; (e) placing a dam means around the flask plate and pouring a liquid which cures into a stonelike material over the flask plate to a depth sufficient to submerge and fully surround the plastic impression; (f) agitating the flask plate and liquid to cause air bubbles to rise to the top of the liquid; (g) curing the liquid to form a stonelike solid member; (h) removing the flask plate from the solid member and thereafter removing the plastic impressions to leave investment cavities therein and trimming said investment to remove any sharp corners formed therein; (i) coating the solid member and walls defining said investment cavities formed therein with a liquid mold release material to enhance subsequent mold release and permitting the liquid to dry; (j) placing a liquid material which is capable of curing into a solid resilient material in the cavities including the steps of: (1) making a first pour of liquid material; (2) pressure packing the first pour of liquid material; (3) making a second pour of liquid material after the first while the first pour is still liquid; (4) pressure packing the second pour of liquid material; (5) repeating steps (1) to (4) until the investment cavities are filled with uncured liquid material free of voids and bubbles; (k) pressure curing the uncured liquid material at a temperature elevated sufficiently to obtain curing thereof into a resilient material; (l) reducing the temperature to a level permitting access to the cured resilient earplug material; (m) breaking the solid member across the cavity to remove the cured earplug; and (n) coding the cured earplug to facilitate the identification of a left earplug from a right earplug using number or color coding.

Claim 2

A method for forming an earplug for reduction of noise when worn by a user which method comprises the steps of: (a) first placing a fibrous pellet in the ear canal of a user past the second bend and thereafter forming a plastic impression of the ear adjacent to the pellet, and wherein some excess plastic impression is formed which excess is partly shaped by the external ear and which reaches the outer end of the ear canal; (b) trimming the plastic impression to form a generally flat face thereon which trimming removes the external ear portion of the impression; (c) coating the trimmed impression with an external wax coating by dipping, and dipping the impression in a soapy liquid parting agent and thereafter permitting the impression to dry at room temperature and thereby harden on the outer surface; (d) glueing the trimmed impression along with a plurality of similarly obtained impressions to a flask plate at the flat face thereon; (e) placing a dam means around the flask plate and pouring a liquid which cures into a stonelike material over the flask plate to a depth sufficient to submerge and fully surround the plastic impression; (f) agitating the flask plate and liquid to cause air bubbles to rise to the top of the liquid; (g) curing the liquid to form a stonelike solid member; (h) removing the flask plate from the solid member and thereafter removing the plastic impressions to leave investment cavities therein and trimming said investment to remove any sharp corners formed therein; (i) coating the solid member and walls defining said investment cavities formed therein with a liquid mold release material to enhance subsequent mold release and permitting the liquid to dry; (j) placing a liquid material which is capable of curing into a solid resilient material in the cavities including the steps of: (1) making a first pour of liquid material; (2) pressure packing the first pour of liquid material; (3) making a second pour of liquid material after the first while the first pour is still liquid; (4) pressure packing the second pour of liquid material; (5) repeating steps (1) to (4) until the investment cavities are filled with uncured liquid material free of voids and bubbles; (k) pressure curing the uncured liquid material at a temperature elevated sufficiently to obtain curing thereof into a resilient material; (l) reducing the temperature to a level permitting access to the cured resilient earplug material; (m) breaking the solid member across the cavity to remove the cured earplug; and (n) coding the cured earplug to facilitate the identification of a left earplug from a right earplug using number or color coding.