Altering fish forms for closed mouths and S-curves is really quite simple. We will start with the closed or partially closed mouth. Since Matt Thompson forms are designed for open mouth poses, we will have to close the opening on the head portion of the form.

In order to assure accuracy, a pattern must be made of the fish before skinning. Dry the fish with towels until it is not dripping wet. Lay fish straight and flat on a paper or cardboard pattern. Make sure the mouth is closed to the position desired. Trace around fish with a marker. This pattern will serve as a reference. Lay the form to be used on the pattern. This should show approximately how much to close the head area on the form.

Make cut as shown on throat portion of form just in front of pelvic fins and also on back portion of head just in front of collar bone. Take a small wedge out, and if the mouth needs to be closed more, you can turn the wedge around to close the mouth even more. Bondo together using pins to hold in position. Sand off uneven edges after Bondo is dry.

Making an S-curve is even simpler. Note (this will reverse the tail action) if the form to be used has the tail action up, after making an S-curve the tail action will be down and with down tail forms, it will change the action on the tail to up. Simply make a vertical cut completely through the tail just in front of the soft dorsal fin and anal fin. Keep the cut the same distance from the end of the soft dorsal fin and anal fin. Reverse the tail part of the form one half of the revolution and Bondo.

After form is dry, simply sand the edges until smooth and even. With some fish such as walleye and striped bass, the back end of the soft dorsal and anal fins are offset. In this case, additional modification may be required. This is easily done with clay.

Partly closed mouths, closed mouths and S-curves tail position are fast becoming the norm in competitions and with customers who want something attractive in a completely natural position.