During elevated ambient and slab temperatures, low humidity or high wind, the rapid drying of SikaColor®-420 Chemstain® may require additional applications to achieve the desired colorations. Lightly misting the concrete with clean water prior to staining can minimize problems associated with hot and windy job site conditions. Evaluate misting technique on your mock-up panel.
Protect adjacent surfaces with plastic. Duct tape should not be used, particularly on surfaces that will be stained, as adhesive residue may leave a shadow or inhibit the reaction of SikaColor®-420 Chemstain®. Blue painter’s tape is preferred. Tape applied to hot surfaces or exposed to direct sun for extended periods will leave a residue. Plastic sheeting or tape should be removed as soon as staining is complete.
Divide the surface into smaller working areas utilizing walls, control joints, and other fixed objects as natural stopping points, ensuring a wet edge during application. Organize application to minimize walking through the wet stain and possibly tracking into other areas. Restrict activity on the floor after it has been cleaned before staining.
During application, avoid random dripping, spillage, and rundown from the equipment, which may produce undesirable colorations that will be difficult to remove. For most applications, a manually pumped or pressurized plastic garden sprayer can be used to apply SikaColor®-420 Chemstain® in a random or circular motion. SikaColor®-420 Chemstain® should fizz when applied. If it does not, additional cleaning is needed, or the concrete is too old and does not contain enough reactive materials for a chemical stain reaction. Keep the saturation amount consistent throughout application. If SikaColor®-420 Chemstain® is splashed, dripped, or puddled, those areas could produce undesirable effects. Evaluate application equipment and techniques with a mock-up panel.
Allow SikaColor®-420 Chemstain® to react on the surface for a minimum of 4 hours. Reaction time may vary with ambient and slab temperatures, wind, and humidity. At low temperatures above freezing, the reaction time of SikaColor®-420 Chemstain® will be extended beyond the typical 4 hours. For single color and multi-colored applications, a small area should be scrubbed and rinsed for effective color evaluation. Additional applications of SikaColor®-420 Chemstain® may be applied to achieve the desired coloration.
Vertical Application
Apply SikaColor®-420 Chemstain® to vertical surfaces in a consistent manner, starting at the bottom and working upward. Avoid excessive rundown of material, as this will produce darker streaks. In confined areas, where a sprayer is not practical, an acid-resistant natural fiber or sponge brush may be used. Proper personal protective equipment (PPE) is recommended during vertical application.
Rinsing
After the final application of SikaColor®-420 Chemstain® has remained on the surface for a minimum of 4 hours, all unreacted SikaColor®-420 Chemstain® residue must be neutralized and then removed entirely before sealing. A solution of baking soda (sodium bicarbonate) and water using 1 lb. (0.5 kg) of baking soda mixed with 5 gal. (18.9 L) of clean water can be used to neutralize the residual SikaColor®-420 Chemstain® acid. Apply the solution until it stops fizzing. After neutralization, the surface must be rinsed thoroughly with clean water several times to remove soluble salts. While rinsing, lightly abrade the surface using a low-speed floor machine equipped with a white pad to remove any residue and/or weakened surface material. Runoff may stain adjacent areas or harm plants. It should be collected by wet-vacuuming or absorbing with an inert material.
After rinsing is complete, a pH test must be performed using litmus paper, pH paper, or a properly calibrated surface pH meter to verify that no residual reactive material is present. A pH value of 7 or greater indicates that all reactive material has been neutralized. If the tested pH value is below 7, the neutralization step outlined above must be repeated until a pH value of 7 or greater is obtained. After neutralization, rinsing, and verification that no reactive material is present, the stained surface must be tested for cleanliness by wiping the surface with a white cloth. If residue appears on the fabric, additional surface cleaning must be performed.
Failure to completely remove all residue before sealing the surface will cause appearance defects, adhesion loss or peeling, reduced durability, and possible bonding failure and delamination of the sealer. All chemically stained surfaces must be protected from traffic until they are sealed.
Sealing
After the stained concrete has been thoroughly neutralized and the rinsed concrete has dried thoroughly, apply sealer.
Use SikaCem®-100 Clear Guard®, SikaCem®-100 PRO 350®, or SikaCem® water-based sealers for exterior applications. Use SikaCem® water-based sealers for interior applications. Consult most current SikaCem® sealer local Product Data Sheets for complete Application Instructions.
Do not apply sealers to concrete substrate with moisture levels > 6% mass (pbw – part by weight) as measured with Tramex® CME/CMExpert type concrete moisture meter.
