This is a huge cubic block of soap. It smells citrus-y. While washing your wool, you rub the stain with a corner of the bar of soap, then rub it in more with your fingers, then rub it out under the water.
We have this favorite pair of WCW lavender longies. Interlock, bulletproof, cuffed bottoms, super comfy, no knit to snag on anything. DD wore them playing outside, eating, and to the park a lot. They have been accumulating stains for a whole year now and there was one huge dark food stain on the butt that was particularly bad and never came out at all. I washed and lanolized them regularly with Eucalan and IV wool shampoo, but for awhile now, they have been just too stained and ugly to wear in public. They had been sitting in a pile with some other food stained (but darker colored so less egregious) longies for a few months in my laundry room. (I have been a lazy pregnant lady for awhile

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So I finally got around to trying this stain bar thingy... O M G. It was a lot of scrubbing, I went over the bad spots twice. The water (a big sink full with some Eucalan, way more water than needed for 2 pairs of longies) slowly turned quite soapy and turbid and dirty looking. So I did another rinse wash with a bit of Eucalan again. Pulled them out. SO CLEAN!!!!! I seriously regret not taking a before pic. They don't look totally new or anything, the color has faded over time for one thing. But NO STAINS. Even the huge old stain on the butt, GONE. I was expecting improvement, but these were old bad stains and I was not expecting a miracle. But I got one! These are perfectly presentable for being worn in public anywhere now!!!
So anyone getting down about your spotty, stained old wool... seriously try this stuff. Amazing.