[txmav]

Any recommendations for a ceramic spray coating that can be used on a car that already has a ceramic coating? I have heard that using these Touch-up coatings can extend the life of the original certain coating.

[cbpip]

Ceramic sparys are not true Ceramic coatings. Some quality detail sprays are intended for extending coatings life.
Make it yourself:
Merlin`s Elixir ( this is the same as what Carpro sells at an inflated price)
A 32oz quality sprayer ( Solo sprayer https://www.amazon.com/gp/aw/d/B000B...b_b_asin_title)
2 oz of Carpro Ech2o
2 oz of Carpro Reload
And fill a remaining 32oz container with distilled Water.
Most detailers are mostly water. This detailer is worth at least trying. Plus you make it yourself and don't pay for shipping water. Wipe off completely.

[Nettles]

Typically good practice is using the spray that is same brand as the coating itself.

[icj_45e]

2nd vote for Merlin's mix. That's what I use. I use it as a drying aide after the primary leaf blower drying method. Mist onto car with any remaining water beads and use drying towel to get 100% dry and apply the touch-up. I recently tried Gyeon's Ceramic Detailer and the Merlin's is easier to apply, with equivalent or better gloss and slickness. My car is coated with Gyeon CanCoat, my wife's car coated with Gyeon mohs evo. Good luck

[txmav]

Thanks. Is the recommended mix safe for PPF? I have XPEL PPF.

[jwmFcreek]

Had some great luck with Jimbos hard as shell … ceramic spray worked very well and easy to install . Good luck