Background:
Plaster has been widely used as the finish surface for interior walls for over 150 years.
Composed primarily of calcium sulfate (hemihydrate), plaster may interfere with LeadCheck
color development because some of the lead may bind to the sulfate in the plaster instead
of the LeadCheck dye. It is possible, however, with a minimum amount of care, to accurately
test for lead paint on plaster surfaces using LeadCheck Swabs.
Method:
- Cut a notch into the paint down to the surface (See Instructions).
Try not to break or scratch the plaster surface.
- Clean the notch by brushing or blowing out any surface dust collected in the
notched area.
- Activate a LeadCheck Swab according to the standard instructions.
- Rub the swab tip into the notched area of the paint for about 30 seconds.
- Check the swab tip, paint surface and paint edge for a pink to red color development.
Interpretation:
- If no pink color develops, be sure to confirm the negative result by rubbing the swab
tip onto a dot on the Test Confirmation Card supplied with the kit. If the confirmation
card dot does not immediately turn pink the test is not valid - surface dust has likely
prevented the LeadCheck color development. Repeat the test using a new LeadCheck Swab.
NOTE: If a yellow or orange color persists at the notched area or swab tip, this indicates the
presence of barium, which was added to paints as an extender. The yellow/orange result is
NOT a positive color change for lead.