Golmex Concrete Look Plaster – Lime/Cement Finish for Walls, Interior & Exterior por | 18 Jul 2026Exterior Brown Coat – The surface should first be pressure washed and cleaned. Let it dry for at least 3 to 5 hours. Mix With Water – Insert 30-36 ounces of water in a 10lb gallon, 150-180 ounces of water in a 50lb bucket.