The concrete has cured for at least 28 days, the surface has been cleaned thoroughly, and the contractor is ready to start applying the acid stain. Or, is he? Did he prepare to do the job safely? Is he wearing the proper personal protection?
Many times contractors take their time preparing to do a good job, but neglect the one thing that is most important to future jobs, themselves! If the contractor does not protect his body properly, there may be problems for him later on.
Acid stain is a coloring product involving a chemical reaction on a cementitious material. A solution mixed with water, acid and inorganic salts react with minerals already present in the concrete, the result of this reaction is color. To apply the acid stain, you will need a 1–2 gallon pump sprayer (without metal parts) to apply the stain. The product will now be airborne and can be absorbed by breathing it. Having the correct *NIOSH approved respirator will protect the contractor from absorbing any of the spray from the acid stain.
“Basically it is common sense - you don't want to breathe anything or get anything on your body if you can avoid it,” said Art Pinto of DecoSup in Miami, Florida. “Just like working with concrete, you want to protect yourself from the products.”
It is important to have as much ventilation as possible when you are working indoors with the acid stains. Murray Lemons of Tropical Decks and Coatings in Apopka, Florida says his crew wears the protection against potential hazards. He also recommends good rubber gloves and safety glasses.
Paul Schneider of Patterned Concrete of Cincinnati agrees. Wearing respirators, eye protection, gloves, long sleeve shirts and long pants are all important. “Because accidents happen and you don't know if you are going to be that person,” said Schneider.
But, he knows from experience that sometimes a guy on the job thinks he doesn't need protection from something he is used to working with. So, the second day on a three-day job, Schneider might find some of his crew without their respirator masks on but complaining of sore throats. He thinks it directly relates to using the acid stain and not being properly protected.
If the contractor is working indoors, a half-mask cartridge-type respirator is recommended. Since the acid stain process requires a sealer be put on afterward, one type of mask could be used for both the acid stain application and the sealer. The P100 series of respirators provides the most protection from acid gases and organic vapors (solvent based). There is an Organic Vapors/ Acid Gases Cartridge with the P100 filter available. NIOSH has three rating levels for respirators, P, R & N. The R series could be used, but will not protect as well as the P series. DO NOT use the N series for this application. For more information about NIOSH ratings, go to the website www.cdc.gov/niosh/respir.html.
Remember to keep a cartridge sealed until ready to use. It starts working the moment it is unsealed from the package. Therefore, someone may be using an ineffective cartridge and not know it. Masks should be kept sealed in a protective package between uses and cleaned after every use, unless a disposable type is being used.
There is a misconception out there that a dust mask will protect workers from the effects of acid stains, but that is not true. There are many varieties of respiratory masks available. MSA, 3M, AO Safety, Drager, Lab Safety Supply, Moldex, North, Pro-Tech, Scott, Sellstrom, Survivair and Willson are some of the many manufacturers of respirators. Using the wrong respirator or using it in the wrong manner can cause employees to become ill on the job and they may not realize the source of their illness right away. Check the MSDS sheet provided by the manufacturer of the acid stain. It will list the ingredients and the proper protection to be used.
Train employees to use their respirators properly. The OSHA Standard 29 CFR Part 1926.134 was updated in 1999. All those who use respirators need to read this standard and follow it to properly protect their employees.
*Refer to 42 CFR part 84 for the specific NIOSH standard information.
- OSHA standard 29 CFR part 1926.134, Respiratory Protection Standard.
- The Web site osha.gov.
- MIOSHA Consultation Education and Training Division.
- Lab Safety Tech Line.