|Yea, thats the point. Washing up to a half hour after exposure with plain water can usually prevent the oil from soaking in. Some soaps help cut the oil too. Alcohol or mineral spirit based products like ivy off can still help cut the oils just a few hours after exposure. They pull the oil out of the pores. But not treating it until the next day can be too late.
The stuff works in the field. You brush up against the p.i., realize it, use the product and it works.
Home remedies on this site are usually concoctions on what to do after exposure and the rash has broken out.
This product if for exposure not relief.
The longer you wait the less chance of 100% removal.