i added to much liquid to my batch of buttercream icing, now it looks to grainy. how can i remedy it to a smooth consistency?

You could (in a separate bowl) make another full or 1/2 recipe without the liquid--subtract what you put in the 1st one-- & then combine the 2 recipes together.

OR

I would probably try adding more powdered sugar if you just added a little too much liquid.

HTH,
bakersofcakes