§ 28. Lien of certain judgments postponed. Upon the filing of the written instrument or instruments of approval under section twenty-six of this article, the lien of all money judgments and attachments affecting such real property, or the moneys due under a contract, and all claims and liens acquired in any proceedings upon any money judgment, shall be subordinate in like manner and to like extent as provided in said section for the subordination of mechanics' liens, and any attachment issued or money judgment recovered upon a claim, which, in whole or in part, was not for materials furnished, labor performed or moneys advanced for the improvement of such real property or for the public improvement, shall be subordinate to all mechanics' liens thereon and shall also be subordinate to all judgments recovered upon and attachments issued upon claims for materials furnished, labor performed or moneys advanced for the improvement of such real property.