water on scatch coat prior to finish render

hello, i am cement rendering cavity blocks and have done scratch coat, should i wet down the walls to help adhesion prior to the final render? also is there an optimum time to leave the scratch coat before the final coat? is it ok to do random scratching too or does it need to be horizontally combed with that rake style? thanks for this..

Sorry for the delay in replying. Only wet the walls down if they are porous - do a suction test by putting a small amount of render on the wall - if it starts to firm up in a few minutes then you may need to damp down, but it will stick without this if they are not too porous. The only time consideration is to make sure no shrinkage will occur due to the setting process still taking place. Not normally a problem with sand / cement more a consideration when working with lime.
The horizontal scratching works well but if you want to be creative you can do random patterns also!
Good luck!

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