I’ve read countless posts about ‘cream’ and still can’t wrap my mind around the concept. Here in Louisville the sidewalks and some driveways are ‘brushed’ if you will and not perfectly smooth. Most drives are aggregate and I feel more confident with those.
I’m super nervous about doing this kind of surface, worried about messing it up with my 4/4 and 25025 tips. Can someone show me a closeup of what it looks like when the cream is removed so I know what to look for if it starts happening?
Not sure if brushed makes a difference or not in terms of still having a cream layer.
Think of a cake. You bake a cake and take it out of the oven. Pop it out of the pan onto a plate. The surface of the cake itself is slightly rough and textured. When concrete is poured and smooth finished it is like adding frosting to that cake.
Now you have a cake with a smooth surface (being the frosting).
When pressure washing, if too much pressure is used, you will wash away the frosting leaving a rough surface behind.
One indicator that this happening is to look at the water coming from your surface cleaner. If it look milky or creamy in any way, you are taking the frosting off the concrete.
And there folks is how to make the analogy between concrete and cake make sense.
I don’t know how technically correct this is, but this is my working understanding:
Concrete is basically just rocks and sand glued together with cement. The rocks make the concrete strong, but they are ugly. If you want to have a nice uniform finish on your concrete, you run a float over it while it is still wet to push all those rocks just under the surface. The “cream” is the wet sand and cement that rises to the top. It’s not as strong, but it has a nice uniform color. The broom texture is made 100% out of cream. Those fine lines are very delicate and you’re always going to take a little bit of that cream off when you wash.
Concrete takes a long time to fully cure, so you have to be particularly careful on new concrete. Maybe up to a year old, you really have to watch it. Good news is that brand new concrete doesn’t usually get dirty that fast. Probably a bigger issue with gas stations and dumpster pads and other commercial stuff that will get dirty very quickly.
But even if it has fully cured, it’s still possible to damage it with enough pressure. Damage will appear as a different color and coarser texture - and it will be in stripes following your spray pattern. As CFH mentioned, a milky color to the water means you are taking off cream.
Over time, the cream will weather away naturally. Sometimes if you look at an old patio, it is smooth right by the wall of the house where it is somewhat protected from the elements. The rest of the patio has a coarser texture where the cream is already gone.
Fascinating, thanks.
I currently have 25025’s for my 4/4 machine, should I consider 2503’s for smooth concrete?
