H.F.
The company that used to make silly putty is now owned by Crayola. They have a wonderful page on their website about getting their products out of things. (Hope this is helpful) This is what they say:
How to remove Silly Putty® from fabric:
Cleaning Materials
Dull knife or metal spoon
WD-40® (car part lubricant)
Liquid dishwashing detergent
Cotton balls
Rubbing alcohol
Soft cloth or sponge
Stain Removal Tips
Scrape off excess Silly Putty with a dull-edge knife or metal spoon. Spray with WD-40 and let stand a few minutes. Scrape excess Silly Putty with dull-edge knife or metal spoon. Respray with WD-40 and wipe off stain with cotton balls. If any stain remains, saturate a cotton ball with rubbing alcohol, blot the stain and rinse. Wipe any remaining residue or remaining stain with a damp sponge or cloth moistened with liquid dishwashing detergent.
Please Note...
The suggestions for removing stains have been compiled as a service to our consumers. We are unable to guarantee or be responsible for the results obtained by these procedures. You may also wish to consult your local cleaner for further recommendations.
Before attempting the stain removal method, test each procedure on an inconspicuous area of the material or surface to be cleaned. Please be advised these stain removal methods involve hazardous products and are intended only for adult use. Crayola does not recommend children attempt these procedures.
In many procedures, specific brands of products are recommended. These are brands that performed most effectively in our laboratory. Always check individual containers for recommended procedures and warnings. Competitive brand products may work equally well.