A question about RAF gas detection patches

[Putty Animal]

Greetings all.

I was taking a look at a new review of the recent Spitfire Mk I from Eduard, and noticed the decal sheet has a number of the 1940 era gas patches featured.  Each one has what appears to be a black outline around it.  Presumably representing some frame or adhesive strip that would have held the panel in place. 

 

Some aircraft seem to have the coloured border, while others don't.  The one below even looks different in the same photo  

 

So I was wondering, does anyone know what the outer frame was?  Perhaps it was a tape that varied from unit to unit.  Perhaps doped fabric such as the type which covered the gunports.  Was it black, red... or maybe something else?

 

All insights are very gratefully received!

 

 

[JackG]

The black outline should really be red dope. 

 

 

 

 

 

 

regards,

Jack

[303sqn]

They are squares of parchment, coated with gas detection paint, held in place with red coloured tape. That way they were easy to replace.

[alt-92]

OT: nice details in that second picture. Heavily worn walkway, chipping around the radio hatch and cockpit, and no crowbar in the door.

[Putty Animal]

Fantastic!  Thank you so much for the info.  That's exactly what I was looking for.  What an amazing place this is 

[Mike Starmer]

The official gas detection patch colour was BS.381 No. 55 Lemon or as near as possible.  Equal parts of Humbrol 81 and 99 match this.  I tend to use 81 only on vehicles since these get grubby.