concurring in part and dissenting in part:
I concur as to affirming the Board’s dismissal of the complaint against Reliable. I respectfully dissent, however, as to enforcing the Board’s order against Dependable.
The majority affirms the Board’s finding that Hartman committed an unfair labor practice because he completed his term as a negotiator for the Association under the then current contract after he notified the Union that he would not be bound by any agreement between the Association and the Union after the contract expired unless he personally signed the new agreement. I do not find anything in the record that supports the Board’s finding that Hartman acted unfairly.1
The Board found that Dependable’s advance notice of withdrawal was timely and unequivocal when given. The notice said that after March 31, 1981, the expiration date of the then existing contract, Dependable would not be bound by any agreement between the Union and the Association unless Hartman personally signed the agreement. Hartman did not sign any new agreement. The Board, however, found that Dependable nullified its withdrawal notice because Hartman remained on the Association’s negotiation committee until the expiration date.
The act of sending advance notice of withdrawal did not strip Dependable or Hartman of their rights and duties under the then existing agreements; a different holding would eliminate the “advance” notice. Hartman was performing the duties of his office as an Association negotiator *1390diligently until his term ended on March 31, 1981.2 He did not attend any Union/Association meeting after the original contract expired. Hartman’s conduct was not inconsistent with Dependable’s withdrawal notice.
The majority cites NLRB v. Associated Shower Door Co., Inc., 512 F.2d 230 (9th Cir.1975), cert. denied, 423 U.S. 893, 96 S.Ct. 191, 46 L.Ed.2d 125 (1975), and Michael J. Bollinger Co., 252 N.L.R.B. 406, enforced mem., 705 F.2d 444 (4th Cir.1983), to support its holding. Associated Shower and Michael J. Bollinger Co. are inapposite. In each of those cases, an employer withdrew immediately. Here, Dependable sent the Union unequivocal advance notice of withdrawal to be effective on a future day certain. The Union knew that Dependable was not going to be bound by any agreement unless Hartman personally signed the agreement. The Union therefore “[knew] with whom they [were] bargaining and who [would] be bound by any agreement that [was] reached.”3
It then became incumbent upon the Union to protest Hartman’s presence when the Union and Association discussed the new agreement. The Union, if it so desired, could have refused to bargain with the Association if the Association insisted upon Hartman’s presence. See Charles D. Bonnano Linen Service v. NLRB, 454 U.S. 404, 420, 102 S.Ct. 720, 729, 70 L.Ed.2d 656 (1982) (Stevens, J., concurring).
I would not enforce the Board order against Dependable.
. Whether Hartman’s act constituted an unfair labor practice is a mixed question of law and fact. See United States v. McConney, 728 F.2d 1195, 1200, 1202 (9th Cir.), cert. denied, — U.S. —, 105 S.Ct. 101, 83 L.Ed.2d 46 (1984). Great weight is given to the Board’s finding on a mixed question which is within the Board’s expertise. Salt River Valley Water Users' Assn. v. NLRB, 769 F.2d 639, 642 (9th Cir.1985). The Board’s finding of fact is conclusive if it is supported by substantial evidence. 29 U.S.C. § 160(e). The reviewing court, however, cannot uphold the Board’s finding if it is erroneous. See NLRB v. Brown, 380 U.S. 278, 291-92, 85 S.Ct. 980, 988-89, 13 L.Ed.2d 839 (1965); Sida of Hawaii, Inc. v. NLRB, 512 F.2d 354, 357 (9th Cir.1975).
. On December 31, 1980, Hartman notified the Association that Dependable would not be a part of the Association after March 1981. His notice said:
This is to inform you that [as] of March 31, 1981 Dependable Tile Company and its officers will resign from your organization. Therefore, as of 11:59 PM of March 31, 1981, we will no longer be associated with your orgnaization [sic] or with any agreements, contracts, or dealing you have with Tile Layers Local #19, its officers or anyone else representing us.
This notice given 90 days prior to expiration of current contract....
(emphasis added).
. The majority emphasizes that all of the Association’s negotiators had withdrawn from the Association by January 1981, and implies that the Association would not have non-members negotiate for it. The majority’s implication is unfounded. Associations do use non-members to negotiate for it. See, e.g., Walt’s Broiler, 270 NLRB No. 99, 116 LRRM 1126 (1984) (employers not bound by a contract negotiated for an association by a hired, non-member representative, even though the employers were members of the association).