I love home-made soaps - and I use them myself... on my body. I'm not bagging homemade soaps at all. But I've owned my salon for 14+ years - and I've got a diploma in Health Science - and I've seen the damage to people's skin that have used inappropriate soap on their face. I'm just trying to offer some professional advice - and if people want to try soap on their face - then it's the risk they take.

Here is some information from eZine articles:
Importance of Your Skin's pH
By Danny Siegenthaler
The role of pH in Acne

As outlined above, the skin’s pH is important and maintaining a slightly acidic pH of around 5.5 is critical.

The skin’s pH value is one of the major contributors to acne and other skin problems. Propionibacterium acnes is a bacteria that normally lives on the skin and is a normal bacteria found in all persons regardless of the presence or absence of acne.

However, in individuals prone to acne, the number of P. acnes is greatly increased. It has been found that the growth of this bacteria is very much dependent on the pH value of the skin and its growth is at its minimum at the normal skin pH of 5.5. A slight shift towards the alkaline pH would provide a better environment in which it can thrive.

Importance of the skin's pH: Do's & Don'ts

One of the major culprits that radically alter the pH of the skin, is soap. Ordinary, commercially available soaps are highly alkaline (pH range 9-11) and raise the skin’s pH to be much more alkaline. This can be adjusted by using products such as Wildcrafted Herbal Products' Wild Herb Toner or Milk of Roses Toner, depending on your skin type. These toners restore normal pH of the skin and thus provide an environment not conducive to the growth of bacteria. In addition, soap dries out the skin, because of its high alkalinity.

Thus if you choose to use a commercially available soap, you must restore the pH of your skin to prevent loss of moisture and the excessive growth of bacteria. It is important to remember that this applies to the entire surface of your skin, not just the face.

Instead of using ordinary soap, you need to use products such as the Skin Renewal Gel from Wildcrafted Herbal Products, which cleanses your skin, removing dead skin cells and leaving your skin’s pH as it is meant to be. Following this with the use of a Toner will close the open pores, preventing blackheads and loss of moisture from the skin.
The skin on the face is more delicate then the skin on your body. And the skin around your eyes is the most delicate of all. And I'm sure most women have been told by doctors not to use soap on their vagina - as this too throws out the pH of the delicate skin down their and becomes a haven for bacteria - ie: thrush.

All I'm going to say is that people should be very careful what they put on their face. The pH of normal, healthy human skin is somewhere between 4.5 and 6 (optimum is 5.5)... and a person should aim to bring their skin as close to that as possible.

AHA's & BHA's are natural - but at the end of the day - they are acid - and they can burn layers off the skin. There are some uses for fruit/lactic acids - but as a skin specialist - I'm not keen on using them unless under strict supervision by a dermatologist.
Tea tree is natural - but this should be used very sparingly - and not on sensitive skin as it too can burn.

I've seen many peoples skin problems (particularly acne/pimples) become worse by using the wrong products. It breaks my heart as I know how bad facial skin can affect a person - and to see it get worse with use of inappropriate products is heartbreaking. Like poor teenagers who have pimples so they think their skin is oily - and use benzol peroxide products (clearasil etc) - only to dry their skin more - and make the congestion/pimples worse. When in fact, their skin is dying for some moisture to allow the natural sebum to escape.