DIY Archival Storage for Unframed Watercolor Paintings

I sometimes get asked how I store unframed finished paintings.  The usual problems that come up when storing watercolors are insect damage, yellowing, spotting and fading.  I had the same problems before but through trial and error, I seem to have stumbled upon a possible solution.

Materials needed:
cardboard sheet
gesso
cutter/scissors
clear tape

clear plastic (medium thickness book cover, or thicker)
ribbons (optional)

To make an archival envelope for the painting, I first made the envelope using a cardboard sheet folded and cut to make an envelope with unglued sides.  Put a layer of gesso on the parts that will touch the painting.  Take away the painting first of course.  Make sure the painting is placed in a safe place where it will not accidentally get gesso splatter when you prepare the envelop.  You need this gesso buffer between the cardboard and watercolor paper to prevent the paper from yellowing or spotting in the future because of contact with non acid free cardboard.  Putting the painting in the envelope will protect it from light which causes fading.

I would then wrap the envelope with two sheets of Manila paper.  This extra layer would act as added protection for the painting against moisture and heat that may get through the plastic casing.  Yes, hard to believe, moisture can get through the plastic but somehow it happens.  Learned in science class of how plastic despite seeming to be waterproof is not completely impermeable (plastic, starch and iodine science experiment).  This may be one reason why during the rainy season when the air can get very damp, watercolor paintings stored in plastic casings still may develop mildew/mold despite being completely encased.  The additional Manila paper buffer seems to do a great job keeping any moisture getting in from reaching the gessoed envelop and painting so I continue the practice to this day.  

 

Above pic shows the plastic casing I made for the pack.  I use plastic sheets (book cover plastic bought by the yard) found in school supplies store locally.  Try to get the thicker kind, they are less prone to becoming brittle.  I would then tape all openings with clear tape except for one side for which I would leave enough plastic that I can fold several times over (for locking).   I then would create a ribbon fastener.  Just tape an end of each ribbon fastener onto the plastic with clear tape.

The plastic casing is a good barrier against insects, moisture, and dirt.  When termites got to my stuff (was storing my supplies and old paintings in a cabinet), it was this plastic casing that saved my old practice paintings (late 1990s).  See pic to the right and bottom.  I like thinking it broke some termite teeth.  They were not able to get in.  The casings were dirty but it took only some wiping to get off the sticky gunk and I was happy to learn the paintings were okay.    

  

Now, seeing as how the paintings fared well over the years with just the plastic casing, why bother with the Manila paper and the gessoed envelop?  Brace yourself, another nerdy moment.  Ahaha.  I learned in a food packaging seminar (Seminar was free and I love free learning experiences) that not all plastics are the same.  Some are food grade, some not.  It is safe to assume some are archival and some also are not. (I was able to buy some archival portfolio plastic sleeves online before so I know the plastic used for artworks is different (label said so)).  While the book cover plastic available locally seems not to yellow, some plastic packaging do.  Some friends have told me they found stored unused paper yellowing despite leaving them in plastic packages.  They noticed only the paper surfaces directly in contact with the plastic had yellowed.  Since we do not know if the book cover plastics are really of archival quality, I make sure the paintings I store now do not get directly in contact with the plastic.

I have been checking the paintings I stored using the new process every few months.  Some I get to check after a year.  Seems to be doing great.  This also lets me air out the paintings every now and then.

For those who will try this DIY, feedback is always appreciated.  This is also a learning experience for me.

As always, thank you very much to readers and supporters for looking in.