It comes pre-mixed in 1-gallon pails, so the color and consistency is perfect every time. Coverage with a Â¼ grout line is approximately 50 sq. ft. for a 12 x12 application. See chart for additional information regarding grout coverage per gallon.
In brief: 48 to 72 hours. The actual placement of the TB skin test (PPD) only takes a few seconds and should be painless. However you need to return to the clinic to have the skin test read by someone who knows what they are looking for between 48 and 72 hours later. In brief: 48 to 72 hours.
Two to three days after getting a tuberculin skin test, the size of any bump at the site is measured. 1  Positive, meaning you have been infected with TB bacteria.  Negative, meaning you have not been infected with TB bacteria or your body cannot respond to the protein injected because of a weakened immune system.