How to protect the back of a mirror from sunlight?

Hi Dwain! Honestly I think any kind of paint would work for this. Black Rustoleum would be what I would use because its oil based and tends to be a lot more durable.

there are spray paints for mirrors and glass that would work for you just look in your local Home Depot type store

Thank you all for your replies and helpful advice.

You could resilver the back. It isn't cheap but if this mirror has value to you look into this.

You can also find the glass paints that cure without heat at Amazon.

Not sure why you don't want to add wood. Best protection for sun. A thin piece of luan and 4 glass clips would not be heavy and give you 100% protection. I would be concerned that a spray paint may be a problem for the silvering on the back of the mirror.

Use like a brown paper bag to cover it just tape it on or glue it

Thanks for the suggestion but number of problems with that. Brown paper bag wouldn't last long exposed to strong southern sunlight. Also, point of covering back of mirror is to protect it from absorbing heat from sunlight which brown paper would intensify. If I decide to cover it with taped on covering, original owner's idea of using tinfoil would be better. Thank you again.

I understand that there is a 2 step epoxy backing paint out there called Grincoat. I think the topcoat of that product would work but am unable to find anyone who sell it. Does anyone out there know where I can buy Grincoat or a similar product?

I would use a spray paint that can be used on mirrors or glass to protect it!

This is a very specific application. I would definitely ask at either a) an antique store since their dealers may have some advice for you or b) at a paint store, a specialty one, not Home Depot. They have more knowledge when it come to the specifics.

Hi Dwain, you can buy rustoleum mirror finish and spray the back with it,

https://www.homedepot.ca/product/rust-oleum-specialty-mirror-effect-170-g-aerosol-spray-paint/1000794333