[Chris Saper]

The thumbnail sketch MUST be of the same proportion as the finished work, otherwise placement and negative spaces become something you have to just guess at. ( As an aside, I have done TONS of paintings where I have "guessed," and guessed wrong...it's better to know.) Be sure to account for the 3/8 inch rabbet that constitutes the lip of the frame. It's a disaster to see a framed portrait where the top of the head (or edge of the sleeve, or knuckle, or stem or anything else) forms a tangent with the edge of the frame.

Sometimes you may know the exact size of the canvas before you begin the thumbnail, and sometimes the thumbnail will tell you the dimensions that the canvas should be. Most conventional portraits will allow enough leeway in the design of negative edges to accommodate standard sizes. Standard sizing aids in the flexibility provided to the client in framing, and very importantly, my ability to keep some beautiful presentation frames on hand, so that I can mange the "first impression."

Sizing is another tremendously valuable feature of the thumbnail sketch. I don't' work over 90% of life size (nor under 50%), so I usually have a pretty good idea of the maximum size I want a subject's head. That dimension then gives me all the information I need to work out negative spaces and figure placement. This is especially important working on a fixed surface (here I am using oils, and I work on a linen-mounted panel), and there is no wiggle room for cropping with a matboard. I have no intention of ever having to go and get my board recut at the end of the painting.

Here the thumbnail has been constructed in three values plus a highlight, and lets me arrange the key shapes into an interlocking design. The three value sketch also will point out obvious "islands" of disconnected values, and other eye-traps...before you even start the painting.