Stains that are found on white underwear may invalidate the seven clean days depending on the size and color of the stains. A clean bedikah afterwards cannot "undo" a problematic stain found on your underwear. If a stain on your underwear invalidates the clean days, you need to perform a new hefsek taharah and count a new seven clean days.

Individual stains found on white underwear that are less than the size of a gris (the size of a US dime or Israeli shekel) may be disregarded. Stains that are larger than the size of a gris and are yellow or light brown (the color of coffee with milk) and do not have a reddish hue may be disregarded as well. Darker brown, pink or orange stains larger than a gris must be evaluated by a halachic authority. Please read our article on stains for further details.

We recommend that you change you underwear more frequently during the seven clean days to prevent any stain from accumulating to the size of a gris.

Further, if you send a questionable stain on your underwear for evaluation, you should continue counting the seven clean days while waiting for an answer from the rabbi. The afternoon bedikah on the day you found the stain can count as a new hefsek taharah if neccesary. You should have in mind that if the stain turns out okay, you are continuing your count from the original hefsek taharah, and if the stain turns out problematic, you are counting from the second hefsek taharah.

Please feel free to get back to us with any further questions.