16. Do you recommend any products for installation, grouting, sealing, maintenance, etc. of a project made with your penny tile sheets?
All tile manufacturers can definitely tell you what products are recommended to install, clean, etc. the tile made by them.
In our case though, the 'tile' is real coins/pennies which are not a 'tile' manufactured by us. Therefore we cannot make any recommendation in this area.
Feel free to consult very experienced, licensed contractors (tile installers) in your local area and also Google whatever was done by others.
We did write an article (with lots of images) that may provide some useful general information about installation and grouting of pennies (link to Part 1).
We also mention in our Terms & Conditions that our only 'contribution' to someone's penny project is providing the ready made penny tile sheets to save them the back breaking, knee pain and time consuming process of gluing penny by penny to a floor, wall, etc.
You'll find examples of people (online) who glued penny by penny for a very, very long time. They also had to decide what products to use for every part of their project. We offer the premade penny tile sheets to improve a painful part of the project and still let the homeowner and/or contractor make those other decisions.
One important thing that comes from someone who tried it and shared their experience online - they say... do not use water-based sealers on pennies because water can/may turn copper green.
Pennies do have some copper content and exposure of copper to water/moisture (for how long?) can turn the copper/pennies green (ex: Statue Of Liberty).
We're sorry we can't be of more help, given that the main part of our real penny tile sheets is the good old penny, which is not a 'tile' made by us.