Which are the most ‘aggressive’ wavelengths?

Someone recently asked me ‘which is the most aggressive wavelength for the skin?’ That’s interesting question… We should first start by identifying which wavelengths we need to consider. In many skin treatments we use visible and near-infrared light – from around 400 nm up to 1064 nm (Nd:YAG) or even 2940 nm (erbium:YAG). CO2 lasers… Continue reading Which are the most ‘aggressive’ wavelengths?

Synchronised hair growth vs paradoxical hypertrichosis

These days, we see many claims of ‘paradoxical hypertrichosis’. Most of the time, these claims are inaccurate – they are not seeing this at all. So, what do these terms actually mean? Let’s define these two terms… Paradoxical hypertrichosis PH (I can’t be bothered writing this out all the time!) occurs when hairs are observed… Continue reading Synchronised hair growth vs paradoxical hypertrichosis

Who needs to cool the skin before lasering????!!!

I just read a comment from a laser hair removal practitioner who was told, by a client, that she had been in another clinic and told that the “results would be better” if she opted not to use the cryogen. In other words, no skin cooling! Clearly that laser tech does not understand what is… Continue reading Who needs to cool the skin before lasering????!!!

Should we wax or pluck before laser/IPL hair removal? The science…

This is an interesting question. Virtually everyone’s initial response would be a resounding “NO”. “Why should we? We would be removing the target we are trying to destroy!!” Well, yes, of course. That’s obvious. Except, it isn’t… A telogen hair, about to transition into anagen 1. To answer this question properly, we need to look… Continue reading Should we wax or pluck before laser/IPL hair removal? The science…

Fluence, pulsewidths, temperatures and cellular denaturation

This topic is very poorly understood. How does fluence and pulsewidth relate to cellular denaturation – or, ‘cooking’ of the cells. I’m going to portray this in a series of graphs – I hope this works… When we fire light energy into the skin, we can generate some heating, if there is something in there… Continue reading Fluence, pulsewidths, temperatures and cellular denaturation

Hair removal – how does fluence relate to depth?

We all know that light energy can kill hair follicles. It has been around since about 1996. But, many people still don’t understand the relationship between fluence and depth in the skin. Let’s begin with fluence – what is it? Simply put, fluence is just the concentration of light energy on the skin surface. If… Continue reading Hair removal – how does fluence relate to depth?

“Synchronised hair growth” – Yes – it is real!

This issue keeps appearing in online forums. Many laser/IPL operators talk about ‘lots of hair growth’ usually after a few sessions. So, I investigated this with my computer model. I had developed this model a few years ago to look at the ‘best’ time intervals between repeat treatments. Last year, while researching laser/IPL treatment of… Continue reading “Synchronised hair growth” – Yes – it is real!

The hair growth cycle in humans

Human hair grows according to a cycle. This cycle can be broken down into three main phases – anagen, catagen and telogen. To understand this process, we need to look closely at the follicles, and their structure. All follicles are comprised of two distinct parts – the upper, permanent part which includes the stem cell… Continue reading The hair growth cycle in humans

The “Hairy Trinity” – How are fluence, follicle depth and treatment frequency related in hair removal treatments?

As many of you know, I like to build and develop computer models investigating how light energy interacts with skin constituents etc. I’ve been doing this since 1987 and am now beginning to get the hang of it!! One model I built, a few years ago, looked at the hair growth cycles across the body.… Continue reading The “Hairy Trinity” – How are fluence, follicle depth and treatment frequency related in hair removal treatments?