I wish there was a maybe for the "would you buy it again"......I said no, but my answer is really maybe, have to wait and get some feedback on the new formula.
This product is not for brushes and definitely not for natural bristle brushes, it is way too harsh. I got this on Amazon and used it only for cleaning my sponges. It took about a month to arrive and it was only 3/4 full, which is a pretty common complaint.
Their newly released version is named DAISO SPONGE & BRUSH CLEANER. The packaging is different, green bottle and it's now 6.8 ounces instead of 2.70 ounces and the price is supposedly the same. That is quite an increase in size with no price increase. I've heard some say the formula is different, others say it is the same, so I guess time will tell. I've seen the newer ones on Ebay but not on Amazon yet. If I decide to repurchase it I want to wait for some reviews on the newly released version. I would think if it is now for brushes too, the formula might have been changed and I would not use a sponge cleaner/brush on my expensive shu uemura brushes, or any of my sable, squirrel, goat or kolinsky brushes. I never used the old formula on those either.
It does work well on sponges but honestly, mine come just as clean when I use a bar of anti bacterial soap. Dial, Irish Spring, doesn't matter. Even nicely scented hard milled soaps work. Beauty bars like Dove don't work as well for me. I just wet the sponges, put the bar of soap in the sink in about 3-4" of warm water water for about 5 minutes so it softens a little, then rub the sponge over it and start squeezing. The soap goes all the way into the center of the sponge and cleans it. Sometimes there will be some resistant stains on the surface but I just rub that area on the bar of soap and it comes right out. When done it is like new, no stains at all.