A technique of combining reversible and irreversible hydrocolloid that could bond to irreversible hydrocolloid is known as:

LAMINATE TECHNIQUE (ALGINATE-AGAR METHOD) A modification of the traditional agar procedure is the combined agar-alginate technique. The agar in the tray is replaced with a mix of chilled alginate that bonds to the agar expressed from a syringe. The alginate gels by a chemical reaction, whereas the agar gels by means of contact with the cool alginate rather than with the water circulating through the tray.  Since it is the agar, not the alginate, that contacts the prepared teeth, maximal detail is reproduced. Because only the syringe material needs to be heated, equipment cost is lower and less preparation time is required. This laminate technique is the most cost-effective way of producing an impression with adequate detail. Reference: PHILLIPS’ SCIENCE OF DENTAL MATERIALS, 12th ed page no 176