If you like myself discovered after purchasing a TS6420a inkjet printer that it is not compatible with printing on cardstock (mine is 67lbs cardstock). I was unaware of this until I loaded it into the back tray and the auto detect feature asks if I added cardstock? I of course select yes. Then it says that I must use compatible media. I tried a few things that didn't work until days later by mistake got it to print from the back tray which still had my cardstock in it. This may not work for every situation also a little warning
⚠️This may damage your printer
⚠️or void your warranty you have been forewarned
Using Android the steps that i took were 1. When adding paper into rear tray I selected Matte Photo Paper. 2. From the app where my image was I selected the share icon, then selected the Cannon print plugging. 3. Once there I selected print settings 4. I changed the media type to Matte Photo then (I believe the following to be the key to force it to print from the rear tray since I was trying to print on letter sized cardstock it would only print from drawer) select Paper Size and change it to a similar size to what your actually using ( I had selected 8"x10") 5. Then print.
Also to note I have only printed with monochrome and have yet to try color. With monochrome there was no smearing and test is crisp and clear. As mentioned this may not work for everyone, since you are not printing to the actual page dimensions if like me your actual page size is Letter size.
I hope this information helps someone else since I could not find any useful information when I needed it. It's just too bad for me I figured it out a week to late
