770 ILCS 70/19: Waivers.

The taking of any note or any additional security by any person given a lien by this Act shall not constitute a waiver of the lien unless made a waiver by express agreement of the parties in writing. The claiming of a lien under this Act shall not constitute a waiver of any other right or security held by the claimant unless made a waiver by express agreement of the parties in writing.