More and more we speak to customers who uncover their concrete, stain, seal and wax normally only to experience surface chipping and scratching with use. Why is this happening?
Not all concrete floors are created equal. Sometimes, especially in the summer, concrete finishers will add extra water to the concrete to make it easier to work with. The finisher will pat the surface with a trowel to bring the moisture to the surface; the water also brings up pure Portland cement which forms a thin soft shell on the surface. The soft concrete surface isn’t a problem if you’re tiling, carpeting or putting down a wood floor. If you’re planning on decorative concrete, it very well could be. Once the concrete is sealed, this soft material can’t wear off with normal traffic. As a result, the stained and sealed surface “shell” will begin to break with use causing the tell-tale scratches, chipping and gouging indicative of this problem.
What’s the solution? Prevention is the best approach. To test for a soft concrete surface, press the tip of nail into the concrete before staining the slab. If breaking or damage of any kind occurs, the concrete must be profiled with a concrete grinder or high speed buffer using a 60-80 grit sanding disc.
If it’s too late for prevention and the slab has already been stained and sealed, the surface does need to be sanded to remove the damaged finish and the soft concrete. Once the sanding and cleaning is complete, the slab is ready to be stained and sealed again. For this and all our pre-application test recommendation, read over our How-to Apply Acid Stain Guide.