SuperLeaf

I am not familiar with Mr. Johnson's  efforts but I employ similar materials in making trees for both my own railroad and the Texas Northern Model Railroad club. Another valuable resource on YouTube are instructional tree videos by Luke Towan.

My current project involves natural Sage Brush, fine ground foam, and SuperLeaf. As almost all trees (with obvious exceptions such as Birch, Aspen, Crepe Myrtle, Palo Verde, (and a few others), the grey bark of the sage pieces eliminate the need for painting. I then remove any extraneous sage branches (small, misshapen, broken stubs, etc.). Larger pieces can be shortened if needed for your application. I trim any rough areas at the bottom main trunk with a fine toothed hobby saw and then drill a suitable diameter hole in the bottom to insert an 18 or 19 gauge wire brad (after removing the head with a cutter) for mounting on the railroad. I use Gorilla Gel to secure the pin to the trunk

The initial step is selecting the proper limb pieces from the SuperTree to build the branch structure I am seeking. I collect a group and insert them into floral foam for painting with a cheap aerosol light grey. Primers can also work but many are too dark, in my opinion.

I start at the top of the sage brush armature as it is easier to progress down the trunk or branch moving downward. I attach the SuperTree pieces using Aileen's Tacky glue as it sets quickly, While it is curing, I hold the branch in position with very small alligator clips. (I also use an Aileen's spray adhesive. I have also used Elmers spray adhesive but prefer the Aileen's)

After the tree has the desired shape and branch density, I apply the spray adhesive from about 12 inches. I use multiple light coats in combination with light layers of SuperLeaf.  My preference is to put the leaf material in a small bowl and  use my fingers to apply the leaf. A suitable sized sifter could also work but I prefer to control the flow. When done, I remove any leaf material from the branches and trunk using an #11 Xacto blade using very light pressure in a dragging motion. 

Thank you for the reply

I like your tutorial about your tree assembly. You have some techniques that I plan to apply to my trees. 

Can you provide a little more information about the leaves themselves? I am modeling the early fall. I have seen lots of trees modeled in this season that look too vibrant. Tom Johnson nailed it and I would like to know what that recipe is or one just like it.

Do you mix the leaves for a custom blend? If so what are your ratios? Were there certain colors you used or others you stayed a way from? Do you start with medium green then layer the yellow and orange colors on top?.

Also, once the fall trees are completed can they be airbrushed to dull down the vibrancy?

@robert gross

Right now, I am only able to find medium green SuperLeaf locally or even on the web. Not saying there are not other stores which have yellows, browns, etc. in stock but I have no idea of how to find them aside from web searching the bigger stores.

Mixing colors is a matter of specific need or personal preference. I use photos as my guide be it scenery or weathering. I am reluctant to mix the SuperLeaf with fine ground foam as the textures do not always emulate nature.

@robert gross

Creating a "how to" blog entry. Should be posted soon.