Putty wash technique is utilized for:

Putty-Wash Technique This method was originally developed for condensation silicone(Polydimethylsiloxane) to minimize the effect of associated dimensional changes. The thick putty material is placed in a stock tray and a preliminary impression is made. This procedure results in what is essentially an intraoral custom-made tray formed by the putty. Space for the light-body “wash” material is provided either by cutting away some of the “tray” putty or by using a thin polyethylene sheet as a spacer between the putty and the prepared teeth during preliminary impression making. One can also generate the space by vacuum forming a blank plastic sheet on a cast and then make the impression with the putty material. A mixture of the thin-consistency wash material is placed into the putty impression and on the preparation; then the tray is reseated in the mouth to make the final impression. Reference: PHILLIPS’ SCIENCE OF DENTAL MATERIALS, 12th ed page no 159,160