We'll maybe I have tough skin.. But I take a tiny bit from the lid.. Never had any sort of burning or itching. Just my opinion and suggestion. You could mix with a little oil if you're worried. There's really no other way to know how long a scent lasts IMO.
This may be your opinion but it is not the opinion of this forum. Please do not suggest unsafe practices on this forum. It is really bad advice since fragrance oils and essential oils should never, ever, ever be used undiluted. They are concentrated! Using undiluted FOs and EOs can cause sensitization, irritation and skin problems. Even using a higher than recommended percentage can cause problems. Example: when I was at school, two of the students were giving each other facial massages. One of the students added peppermint EO to the oil because she wanted to "stimulate" the other student's skin and increase blood flow. These students had limited knowledge of EOs, didn't know only a few drops was enough and assumed because it was natural, it wasn't harmful. To make a long story short, screaming, running down the hallway, crying, frantic washing of the face. The student's face was red. I mean a bright red which looked like a sunburn. Her skin was very irritated and took quite awhile to return to normal.
I was sent some soap for feedback and the soap irritated my skin because the member used too much FO. The only way to know how long a scent will last is to actually use it in soap, lotion or whatever. Then keep a bar or a few ounces for an extended period of time (months, year, longer, etc) to see when and if the scent fades. This is why we recommend testing. There is also info about FOs which stick and those that fade on this forum. You can also join the
Soap Scent Review Board for info on which FOs last and which fade.
I know the link below is to an article about essential but it's still helpful to apply it to FOs.
http://www.aromaweb.com/articles/dilutingessentialoils.asp
BTW, please don't be upset by my post. I'm not saying this to be mean. I just don't want someone to be hurt.