When it comes to doing re-skimming one has to be careful especially when re-skimming over non-porous surfaces such as vinyl silk or gloss painted surfaces.

If PVA adhesive is appliled to these surfaces it would start to run off the wall due to the lack of suction in the wall and the glue can hang around for hours still wet. Finish plaster should only be applied to PVA which has gone tacky or sticky.

The best practice though for doing re-skims is to use an aggregate based adhesive/primer. This product adheres to the wall and acts as an excellent mechanical key. This type of product can come in a red or green color and because of the color, it is difficult to miss anywhere. Although the aggregate based adhesive primer system is more expensive than PVA it will not let you down and it is much more reliable. So my advice, don't try to compromise on cheap materials only use the best!