After the formwork is removed and you see that certain corrective steps must be taken the following suggestions may be helpful. To remove fins, curtains and surface air holes, rub over the area with a fine or medium Carborundum stone. A Carborundum stone will also fill up most of the smaller air holes, if the concrete is no more than a day or two old. To patch holes left by form bolts or ties, clean the hole by pushing a piece of cloth through it to remove grease of form oil. Next, wet the hole. Then ram the mortar well into it with a rod. Wipe the outer surface with a damp cloth or rub down with a wood float. To correct honeycombing, cut out the defective concrete. Clean the exposed surface and wet it thoroughly. Then brush a neat cement grout well into it. Immediately afterwards, fill up the entire area that has been cut away with a mortar patch of earth dry consistency. Finish the surface with a wood float.