The first Estes igniters I remember seeing had a blue dip coating. All the old igniters I have left have (the later) brown coating.
The dip was never as smooth as the catalog drawings. There were drips and globs down the wire.
The engine tubes had three igniters all on one single piece of wire. You would cut the wire into three separate pieces.
The coating was a sort of pyrogen. You no longer had to wind bare nichrome around a paper clip or tip of a ball point pen. The coating also insulated the bent end and prevented shorts.