The following information is from Terry Martini, who has restored many 

Ferrograph/Vortexion machines.

Life is never straight forward when it comes to matching what you think is a
fairly standard color. I can say for certain that the original grey used on
the military and industrial stuff was Light Battleship Grey and the original
BS number was BS 631 see the link here:

These days they are known as RAL numbers. Ferro did not disclose the later colours but they
would have been fairly standard and with a BS number. 

Now the other problem facing anyone wanting to touch up a Wearite deck is
this: There were at least 3 different shades used over the years including
grey/blue as seen on the series 2 etc through to a green grey as used on
Series 4 5 6 etc. 

The paint used was cellulose based and probably the best
source these days would be a good vintage car paint supplier who will
probably be able to supply a small spray can of the stuff. There are one or
two specialist paint suppliers who can match any colour and type going and
also supply a can of the stuff, there are certainly websites about as well.
Being standard colours though a match should not be difficult. 

Brushing it on will look terrible! 

So I would recommend either spraying or using one of the touch up pens. 

In the days these decks were made, there were a limited
range of paint colours due to the nature of the paint industry and a general
lack of pigments. Now you can get a 1000 shades of red if you want all mixed
by computer!

Hope this is of some assistance and many thanks to Terry Martini.

Brian Moore who asked about the paint matching for the Vortexion / Ferrograph machines has now done a stunning refurbishment on a Vortexion WVB4

and adds the following tips that may help others with the same problem.

A visit to my model shop showed acrylic paint made by Tamiya ref XF-14 is very close to the Vortexion WVB with the Wearite deck and would suit small touch ups.

  A re-spray of the complete deck would need the Admiralty Grey which was available from Phoenix Paints at www.phoenix-paints.co.uk

 The black rexine case came up very good indeed with Dylon black leather shoe dye; in fact I found a single bottle covered the whole case with one coat.

  I replaced all the leaky Hunts capacitors with new Polyester types and cleaned all switches with Servisol and greased the sliding mechanism of the Mk4 deck.

It was mainly the area around the sliding "Run" switch which needed retouching this is the most handled part of the deck I suppose. The rest of the deck responding very well to T-Cut and then a good car polish.

  I used Halfords general purpose grease for the sliding mechanism of the deck. It is best applied with a thin spatula or stick so as not to get it on any of the drive components. The result makes the functions very smooth and switching from say Record to Playback much less clunky.

  The Dylon leather shoe dye should work well on the rexine covered Ferrographs as well.  Stick down all loose bits of material with Bostick, clean case with soap and water and nail brush. Then rub with meths before applying the Dylon shoe dye.

  This dries quickly but is best left overnight for a better finish.