What is the legal test for waiver of a contractual right to arbitration?

Waiver of a contractual right to arbitration is ordinarily a question of fact and determination of this question, if supported by substantial evidence, is binding on an appellate court. (Sawday v. Vista Irrigation Dist. (1966) 64 Cal.2d 833, 836, 52 Cal.Rptr. 1, 415 P.2d 816.) Under the general rule this question is left to the trial court where there is substantial evidence to support it. However, in cases where the record before the trial court establishes a lack of waiver as a matter of law, the appellate court may reverse a finding of waiver made by the trial court. (See Seidman & Seidman v. Wolfson (1975) 50 Cal.App.3d 826, 123 Cal.Rptr. 873.)