ENHS Nature Trails Nov. 97 Article 5

The Simplest Method of Preserving Leaves
by Dave Wagner

This year is unusual in the lateness of leaf drop. Many of the deciduous trees in town still have a substantial leaf load. In most years our street trees, with the exception of the liquidambars, have had all their leaves blown down by the first storms of winter. This means that there are still a lot of beautiful leaves on trees all over town, leaves you might want to preserve to brighten the days ahead.

One of the ways to enjoy this color is to preserve it in the form of pressed, dried specimens. I had a vine maple leaf on display in a picture frame for over fifteen years, exposed to the light all that time. Even after that it has retained beautiful colors and patterns very close to the original fresh leaf. The trick to preserving leaves for display is not so much the pressing as the drying. If a leaf takes too long to dry out, it loses its color. The pressing is important, however, because a dried leaf is rather fragile and when flattened it's most easily mounted for support.

Professional botanists use a fancy plant press and electric drying frame to prepare leaves (or entire plants) but anybody can do a professional job with just dry newspapers. It's the good old way, how it was done before the invention of corrugated cardboard.

First, prepare a number of specimen folders by cutting the spine of a newspaper section and separating the pages into single thickness folders. Keep handy a number of whole newspaper sections containing 8-16 (2-4 double sheets) folded the same size as the specimen folders (Figure 1). These will serve as blotters, so keeping your newspapers in a dry place (i.e., not a damp garage floor) is important.

Place your specimens (carefully chosen leaves) into the specimen folders being careful to avoid overlapping or parts sticking out the edges of the folders. A pressing stack is built up by alternating blotters and folders, blotters at both top and bottom of stack. If they open in opposite directions, it is easier to handle them in the drying process (Figure 2). Find a sturdy board that's just a bit larger than the newspaper stack (12" X 18" is usual) and put it on the top of the stack. Weigh it down with rocks or any other heavy objects which are easy to handle; a minimum of 25 lbs seems a good rule of thumb. An easy way to attain this is to use four plastic gallon jugs filled with water. Fill them with pea gravel and you'll have closer to 50 lbs, more than enough. This is your pressing stack.

The secret of good color preservation is rapid drying while the leaves are being kept flat in the pressing stack. This is done by wicking: the blotters (full newspaper sections) draw moisture from the leaves in the folders. After the rate of moisture withdrawal slows, the damp blotter is replaced with a fresh, dry blotter. Efficient drying means replacing blotters twice a day for the first two or three days the specimens are in the pressing stack. Once a day after that is O.K., to be kept up until the leaves are perfectly dry. This takes 10 days or so for most leaves. You need blotters which are bone-dry for the last few changes. Test by pressing a specimen to your lips: if a leaf is still moist it will feel cool. Dry leaves feel like a sheet of dry paper. (All the Newts that fits... returns next month. Send in your notes; e-mail to: davidhwagner@compuserve.com)

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