Oxygen indicator for packaging

DETAILED DESCRIPTION What is claimed is: 1.
An oxygen indicator for use in an atmosphere free of oxygen, said indicator comprising a substrate carrying, in leuco state, a dye free of reducing agents and this reducing agent free dye being capable of irreversibly reacting with oxygen; said dye being characterized as being of the class which is reactive with oxygen to change from the leuco state to the colored state and which is reactive with reducing agent to change from the colored state to the leuco state.
2.
The indicator of claim 1 wherein the dye is a basic thiazine dye.
3.
The indicator of claim 1 wherein the dye is a triphenylmethane dye.
4.
The indicator of claim 1 wherein the dye is methylene blue.
5.
The indicator of claim 1 wherein the dye is new methylene blue.
6.
The indicator of claim 1 wherein the dye is thionine.
7.
The indicator of claim 1 wherein the dye is methyl violet.
8.
The sealed package containing the indicator of claim 2 in an atmosphere free of oxygen.
9.
A sealed package containing the indicator of claim 3 in an atmosphere free of oxygen.
10.
A sealed package containing the indicator of claim 4 in an atmosphere free of oxygen.
11.
A sealed package containing the indicator of claim 5 in an atmopshere free of oxygen.
12.
A sealed package containing the indicator of claim 6 in an atmosphere free of oxygen.
13.
A sealed package containing the indicator of claim 7 in an atmosphere free of oxygen.
14.
A sealed package containing an oxygen indicator in an atmosphere free of oxygen, said indicator comprising a substrate carrying, in leuco state, a dye free of reducing agent and this reducing agent free dye being capable of irreversibly reacting with oxygen; said dye being characterized as being of the class which is reactive with oxygen to change from the leuco state to the colored state and which is reactive with reducing agent to change from the colored state to the leuco state.
15.
The package of claim 14 wherein the atmosphere in nitrogen.
16.
The package of claim 14 wherein the atmosphere is carbon dioxide