How Do I Sell Non-Archival Art As Archival Art?
On the occasions that I create a non-archival piece that I am fond of and I believe that it would be well received at galleries. I have a giclée print made. 

Technology has advanced so much recently that it is possible to have a high-resolution print made of your art that could actually last longer than the art itself. Giclée printing uses pigment based archival inks and are printed on archival substrates to ensure your art will last 100 + years without noticeable fading. 

If you have created a piece with non-archival materials but it really turned out nice and you want to offer it as an archival piece, giclée prints are an excellent option.

To have a giclée made of your art you'll have to capture a high quality photo or have your art digitally scanned. The best way to get a color correct match is to deliver your art to the giclée creator in person or via shipping.

It can be said that a giclée print is not an original piece of art. While this is true, you can make it original. You can embellish the giclée print by adding little touches of paint to accent certain areas or add paint embellishments wherever you wish. You are adding your own personal touch to make it unique to that particular print! 

I do this often and I sell them as hand embellished art prints

It’s all about being ethical and providing full disclosure to your customers. Explain to them how the art was made, the materials that were used and why you deploy your particular pricing structure. 

An informed customer will become a loyal customer.