Acid Stain Application Guide
Introduction
Universal Concrete Acid Stain produces deep colouring effects in old and new concrete surfaces. Colours are produced by combinations of metal ions in the stain solution forming permanent colour complexes within the pores of the cementitious materials. The acid in the stain solution dissolves loose materials in the pores of the cement, allowing deep penetration of the colouring ions, and therefore a long lasting permanent colour.
The colours are deep, rich and natural, and the overall effect of the stain will be dependant on the uniformity of the concrete itself. Because the colour is produced by penetration and chemical reaction, the peculiarities of the surface will produce varying degrees of mottling. The resulting colour of the staining procedure is often described as having the variegated appearance of old world materials like marble, or the coloured layering of time worn ancient patinas, comma or the natural, organic colours in landscapes. Unlike surface coatings that give a uniform colour treatment to all surfaces, Universal Concrete Acid Stains give a unique treatment to each application.
Surface Preparation
New concrete should be allowed to cure a minimum of 14 days, preferably 28 days. For existing concrete, it is essential to remove any previously applied coatings (such as paint, water repellents or adhesives) using the preferred methods of shotblast or sandblast. Completely remove all dirt, oils and stains from surface by pressure washing, or scrubbing with a stiff bristled brush. Protect surrounding areas from over spray, spills and runoff.
If the concrete substrate is uneven or too damaged to stain, a self-levelling concrete topping, material may be applied prior to staining. Contact Universal Concrete Accessories for details.
Application
Do a small test section to check suitability of the stain.
Try to plan sections to have natural breaks to avoid overlapping applications of the stain. Uneven distribution of the stain can make undesired colouring. An all-plastic pump-up sprayer with a fan tip lays down an even coating of the stain. The stain should be immediately worked into the concrete with a nylon brush. The stain will foam for a while as the acid reacts with the loose materials in the pores of the concrete. If the acid does not foam, stop immediately and prepare substrate again.
Allow about eight hours for the stain to set and then wash and brush residue off of stained surface. The concrete should be neutralized with a mild baking soda or ammonia solution and checked with a pH pen to verify the neutral pH. Rinse until water runs clear and a white rag will not pick up any colour. This is very important for the subsequent application of any sealers or finishes. Collect and properly dispose of all rinse water (dyke and wet vacuum).
Note: Application time of acid stain and the removal of residue are dependant on the concrete substrate. Some substrates may require two or more applications of stain and require longer periods to react with the substrates.
Coverage
Coverage rates should be based upon the development of samples for a specific project or application. Coverage will depend on application technique, age of the concrete, porosity and texture but should be approximately 100-200 square feet per gallon per coat.
Considerations Before Using Universal Concrete Acid Stain
The finished appearance of an acid stain application is heavily dependant on application technique and type of surface. Acid stain will usually not correct faults or discolouration of the concrete substrate. Moisture, cement and fly ash content will affect the finish of the stain. A 28 MPA (4,000PSI) slab mix will stain differently than a 32 MPA (4,600PSI) exterior mix. Samples and mock-ups are strongly recommended. Final results are highly dependant on application technique and should be applied by someone with extensive experience in staining.
While Universal Concrete Acid Stain is manufactured to exacting standards for uniform quality there is no expressed or implied warranty as to the effects of its use. The colour effects produced by Universal Concrete Acid Stain are highly dependant on application technique, and the condition of the surface to be treated. The user must therefore determine that the method chosen is suitable. Warranty obligations will be limited to the purchase price of the stain.
Personal Protection
Universal Concrete Acid Stain is an acidic solution. It is imperative that adequate personal protection is worn, and that includes; rubber gloves, boots, apron, eye protection, and a suitable respirator for acid vapours. Do not use metal sprayers or containers.
Material Safety Data sheets are available upon request.