If a vintage poster is in bad condition, but it is rare and sought after, it could be worth to restore it. In case of noticeable yellowing or discoloration, bleaching could be necessary. Ask paper conservation professionals to do this, never try it by yourself! They work for museums, archives and collectors too.
A professional conservation of a vintage poster is an important feature which will increase its value. Main problem is, that vintage posters have been printed on cheap, low quality paper. A backed poster is easy to handle, ready for framing, and it can be rolled for shipping. Please store posters always flat and never rolled!
First: Possibly existing old tapes must be removed by careful use of chemicals.
The next step is washing the poster. Washing allows the fibers to swell open, cleans the surface and neutralizes acidity. In case of being rolled for a long time, the paper
can relax now and gets back its original size.
In case of significant yellowed paper, metal caused dots or foxing (brown dots caused by fungus), it could be necessary to bleach the poster. Bleaching could be done by many different procedures, ask an experienced restoration professional for the best choice to solve your problem. The pictures show partial bleaching at the margins with a brush (above) and in a bath of potassium permanganate (down).
After a few minutes the procedure is stopped by potassium metabisulfite. Afterwards the poster is washed in water again, a small amount of buffer (calcium hydroxide) is added to reduce the ph for future.
When removed from the sink, the poster looks really good. It is ready for backing now.
is the most common archival poster conservation method, preferred by dealers, galleries and many collectors. The poster is de-acidified and mounted with wheat paste onto acid free paper and adhered to canvas. Linen backing provides stability to the poster, it smoothes and flattens out waves and wrinkles and makes creases and folds invisible or less noticeable. A linen backed poster can be removed from canvas and paper without any damage. This cannot be said for common dry mounting methods.
is a common archival poster conservation method too. The poster is de-acidified and mounted with wheat paste onto a piece of thin high quality acid free Japanese rice paper.
Paper backing has the same advantages like linen backing, except the stability. But on the other hand it still feels like original paper. In case of framing you don’t need a mat to cover the
canvas. This method is recommended by museums worldwide, a lot of European collectors prefer paper backed posters too.
This poster conservation method is recommended for posters in very good condition only. A starch backed poster has been flattened, cleaned and de-acidified, but fold lines will usually still be noticeable. It’s not mounted to anything, it feels like the original.
The backing is made by use of powdered wheat starch and a small amount of buffer (calcium carbonate) mixed with pure water.
The last step is restoration of missing or damaged details in the image. Missing areas are replaced by use of original vintage paper similar to the original. Scratches or missing details in the image are retouched. Professionals will use methyl cellulose to protect the original poster from all colors which are applied for restoring purpose.
A lot of vintage posters have been destroyed by sunlight. Exposure to UV light accelerates the crystallizing of paper’s cellulose chains. It causes premature stiffness, brittleness and discoloration. It will also cause inks, dyes and paints to fade and discolor. If posters should be displayed, UV filtering plexi should cover the piece. Never place framed posters in direct sunlight!
The best thing to do is to change displayed posters twice a year. I prefer professional frames manufactured by HALBE. These frames are easy to use, a magnetic mechanism allows to change the artwork very comfortable. HALBE frames are recommended by museums