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-Step TB Skin Test. The 2-step test is not the usual PPD skin test in which you receive an injection of PPD and the test area is observed one time at a specific time frame. The 2-step PPD test is used to detect individuals with past TB infections who now have diminished skin test reactivity.