This was requested by a friend a couple of weeks ago, and I finally made it today. Based on the research and recommendations made here on SMF, I used 10% pine tar with a combo of tallow and palm increase hardness, plus some PKO, castor, and sorbitol to increase lather. 2% SF and 40% lye concentration.
As for the smell,
at the last minute I decided to use a lavender-chamomile-pine blend (thank you @cmzaha for introducing me to this lovely combo). This blend did a great job working with the burnt tar smell of the pine tar.
Nod to Ellie's Everyday YT channel for the recommendation to mix together everything except the lye solution so that the pine tar is well mixed with the other oils and additives. But I must admit to becoming impatient after pouring in my MB lye solution and hand-stirring for hours (ok, about 90 seconds). Well, two seconds with the stick-blender changed that oily liquid into chocolate pudding! It still went into the molds easily and is gelling itself out in the open as we speak.
Glad I checked on these. Just three hours later, they were hard as rocks and almost falling out of the molds. They were definitely firm enough to cut, but the wire left really bad bumps, despite soaping fairly warm. I did use some fairly old PO with visible stearic bits that were hard to melt. No doubt these bars are higher in stearic than the calc showed, and that may be why it firmed up so fast.
Ah well. It was never meant to be a show soap. 
As for the smell,
at the last minute I decided to use a lavender-chamomile-pine blend (thank you @cmzaha for introducing me to this lovely combo). This blend did a great job working with the burnt tar smell of the pine tar. Nod to Ellie's Everyday YT channel for the recommendation to mix together everything except the lye solution so that the pine tar is well mixed with the other oils and additives. But I must admit to becoming impatient after pouring in my MB lye solution and hand-stirring for hours (ok, about 90 seconds). Well, two seconds with the stick-blender changed that oily liquid into chocolate pudding! It still went into the molds easily and is gelling itself out in the open as we speak.
Glad I checked on these. Just three hours later, they were hard as rocks and almost falling out of the molds. They were definitely firm enough to cut, but the wire left really bad bumps, despite soaping fairly warm. I did use some fairly old PO with visible stearic bits that were hard to melt. No doubt these bars are higher in stearic than the calc showed, and that may be why it firmed up so fast.
Ah well. It was never meant to be a show soap.
