Abstract: There is disclosed an article treating apparatus particularly apparatus for pressure-impregnating or vacuum impregnating porous articles such as metal castings. A holder for the articles or a metal basket containing them is disposed in an autoclave and can be rotated about a horizontal axis. It has a horizontal through-passageway so that articles to be treated can be simultaneously loaded at one end of the passageway and unloaded at the other end of the passageway by an indexing mechanism. The indexing mechanism has a plurality of pusher arms which can be moved laterally into the path of the articles and then moved horizontally to push the articles along rails into and out of the passageway. The holder is stopped at a predetermined rotary position in which a longitudinal slot is opposite the pusher arms so that unloading and loading may be effected simultaneously with a single movement of the indexing mechanism, a pusher arm passing completely through the slot.

Abstract: A pressure vessel for use in impregnating porous articles comprising a support member for the articles, slidable between an upper position for degassing the articles and a lower position for impregnating the articles, a release mechanism operable from outside the pressure vessel to permit the support member to descend from the upper position to the lower position under gravity, and damping means at least partially within the pressure vessel for controlling descent of the support member.

Abstract: A method of impregnating a porous article with impregnant to seal the pores thereof, which comprises placing the article in a vessel, evacuating the vessel to withdraw air from the pores, releasing the vacuum with the pores beneath the surface of a liquid impregnant in the vessel, removing excess impregnant from the vessel, washing excess impregnant from the surface of the article by supplying washing fluid to the vessel, removing the fluid from the vessel, heating the article while still within the vessel to effect curing of the impregnant within the pores, and removing the impregnated article from the vessel.

Abstract: This invention relates to the impregnation of rigid porous articles, particularly metal castings. In its preferred form the impregnant is a liquid mixture of monofunctional (meth)acrylic ester and a relatively small proportion of polyfunctional (meth)acrylic ester to provide a cross linked product on curing and to facilitate washing of the casting with water and an emulsifier. A peroxy or other free radical catalyst such as AZBN is associated in the impregnant with an inhibitor such as a hydroquinone derivative so that curing can be effected at a temperature of 90.degree. C. within 3 to 15 minutes. Curing is preferably effected by immersion in a hot water bath.