With its extended working time, fresh mixes of ARDEX K 39 can be easily smoothed into existing pre-applied material up to 40 minutes after application.
This gives the installer more time to focus on creating the perfect subfloor, with no trowel marks, ridges or joint marks, or additional preparation the next day.
For more information view ARDEX K39 HERE
Also, you can check out the YouTube video all about ARDEX K39 HERE