OK,will not need a how to for this really, but feel free to add it to the how to list Admin.The products are purchased on eBay from a company called The Leather Clinic .They supply everything you need for the job of colouring leather. The kit will include leather prep,alcohol cleaner, colouring dye, gloss or matt finish ,clothes and sponges plus instructions that I understood so they were obviously simple to comprehend. You use the sponges mainly and they do send a few of them !
Firstly the job is to hoover and clean the seats, second is to prep the seats by dabbing on the prep cleaner.Then get rid of the prep by using alcohol cleaner on the leather. Give the leather an hour to dry out and then you can start to colour with the colourant. Again dabbing the leather with another new sponge,this is where a bit of care is needed. Don't go mad with it,less is more as they say. Put too much on and you get lots of bubbles that you then have to keep dabbing to get rid of. !!
I normally do 3 coats of colourant,leaving at least 20 mins between each coat. If you are doing headrests or whole seats it keeps the job simple. If doing panels on seats like my green ones ,just masking tape will suffice.
Then after the third coat has dried ( wait at !east an hour before putting the leather finish on ) again,with the dabbing technique with a new sponge,2 or 3 coats of finish and your done. Leave the seats for a couple of days ( to be safe lol ] , dont want those pristine white shirts of yours getting an added splash of colour !! The cost will depend on what you order, quantity wise, its not expensive for what you get as a finished article. The colour will last years ,i used my 16v coupe every day and it doesnt wear at all. Pictures are on this thread, admin feel free to add photos of my red seats and green seats to this how-to. Get dyeing folks !