Tinted Tubes

Manufacturers started to add a small amount of mercury to the mixture in the tubes to (drastically) increase their life-span. However this caused a blue glow around the orange neon glow that some found reduced the overall visibility. To counteract this companies started to offer tubes with an optional transparent red or orange coating, that filtered out the blue glow.

This coating is often removed these days, which is simple to do with just warm water. This is especially true if the coating has started to peel off. Conversely, some people dip clear tubes in modern transparent colored coatings.

The down-side to doing this is that it removes the original markings on the tubes, which can adversely affect their value.


This version of the GN-4 has a red-coating and a decimal point on the left and was manufactured by Lorenz SEL.


ITT GN5. A medium-sized top-view Nixie tube


The XN3 numicator is a medium-sized nixie tube made by Hivac of England.


A Z568M tube manufactured by WF/RFT


The ZM1020 is a top-view Nixie tube with a red coating to increase contrast. This one was made by Telefunken. It is one of many tube types with a B13B base.


The ZM1040 was made by many manufacturers, with slight differences in internal construction between them. This one was made by Tesla.


The ZM1041 is a large Nixie tube that can display a plus and minus symbol. It has a red coating to improve contrast. This particular one was made by Mullard of the U.K.


The ZM1080T is a medium sized nixie tube made by Tesla in the former Czechoslovakia


The ZM1174 is a version of the ZM1175 with a red tinted coating to improve contrast