I ordered so fabric dye from Quebec (Simply Spray). It is permanent ones it follies dries in 24 to 74 hours.
1/ make a template on a sheet of cardboard for each mat. Do not reuse the templates because the dye soaks into the paper and will lift.
2/ Tap the template to the mat to hold in place and prevent any lifting.
3/ spray the dye evenly across the template, it may take more then one application to get the colour you are trying for. The light red turned darker on the black mats, but it’s still ok.
4/ remove the template from the mat, be sure to lift smoothly away and take care to watch for drips. If you have any over spray you can wipe it of with a wet rag. Ones it has dried you want be getting the dye out any more.
5/ place mats in a warm, dry area where no one will touch them for 24 hour (at least).
Then just repeat for each mat. Finish one matt at a time to be able to clean off any over spray or drips.