Actually, these are great to use all the time, not just on new clothes.
I've lost count the number of times I've tossed one in with "old" clothes (stuff that's been washed several times) and am surprised to see just how much color was actually grabbed. But then other times nothing. I also noticed that before using these I would have clothing that had white in it which (even if washed in cold) would turn colors due to the dyes of other colors on the garment. For example, my daughter had a dress in which the top half was white, the bottom half was dark purple velvet. I washed it cold but the purple still bled and turned the upper half (which was white) to a light purple. Thankfully in that case it was alright, didn't ruin the dress, and almost looked like that's how it was made. But other stuff, like red mixed with white= pink (even when washed cold) hasn't been so lucky.
Anyway, I've noticed with these sheets that this isn't happening anymore- the color bleeding is being absorbed by the sheet.
Oh, I did a load of towels one day and out of habit tossed a color grab sheet in with it (even though all the towels were the same shade of blue). I washed them warm, and these are towels that have been used and washed countless times. Well I was very surprised to pull the color grab sheet out and see it was all blue too, you would think after washing so many times that there wouldn't be any color left to transfer, but apparently there was.
These seem to be the 2 main brands I've seen around. I've tried both and personally, I prefer the Carbona Color Grabber (yellow box on left)
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