The following is an extract from a chapter on self-tan products from Beauty Scoop: The indispensable guide to the best beauty products on the market by Julia Carling and Kate Shapland

The mission: to find you the most effective and user-friendly self-tans on the market. The criteria: our testers judged the self-tanners they tried on their ability to give skin the most realistic fake tan, the speed which the colour developed and the smell - whether it was bearable or telltale (important, because most of our testers said they thought self-tans still smelt awful). They also judged self-tans and wash-off tints on their ability to moisturise skin, ease of application, and lifespan.

L'Oréal Sublime Bronze Self Tanning Gel £9.99 for 150ml
Annalise (25) said this was 'one of the best self tans', and although Bridget (38) wasn't convinced by the smell, she felt it 'lasted better than any other I have tried, and I really loved the way it made my skin feel so soft'. As well as smell, lasting qualities were really important to our testers. Lily (41) commented: 'I used this on my arms first of all and it lasted for at least five days before looking a bit tired - even then only I noticed this. It faded gradually rather than in patches. I then did my face and legs and got the same results. Really great stuff.' Our testers agreed that the tan was very realistic, and that it was a joy to apply because it is tinted so you can see where you are putting it.
The science bit: as well as the active tanning ingredient, it includes AHAs, the chemical skin-smoothers which L'Oréal say helps to prevent streakiness.

Clarins Tinted Self Tanning Face Cream £13.50 for 50ml
Eve (37) is very fussy about self-tan; she says she has never found one she is 100 per cent convinced by, and even though she wasn't mad about the smell of this product she still gave it a high rating because 'it gave me a really good, healthy looking tan, and although I'm fussy about self-tan, I was impressed and would definitely buy it despite its smell'. Vicki (40) doesn't really use self-tan on her fair skin but was convinced by this one, saying 'it was really good and a great natural colour - I didn't look at all orange as I feared I would'. The added bonuses with this self-tan is that it has an SPF15 and it is tinted so it gives your skin an instant glow and you can see where you are applying it.
The science bit: as well as DHA, it contains skin conditioning and tanning ingredients ayapana, birch bark and olive leaf extracts.

Sisley Self Tanning Gel £40 for 75ml
This is available in two shade formulas - one for fair skin and two for dark - and can be used on your face and body. 'Really impressed with this,' wrote Anneka (28), who used the formula for pale skin. 'I only used it on my face and even though I'm not a pro when it comes to self-tan I managed to get it on without any streaks - although I think that's down to the performance of the product rather than me - and all the colour I needed in one application.' 'More of a cream than a gel,' wrote Cindy (50), 'but a cream with a really light texture - superb. It works quite fast - just over an hour to a tan, so I was able to use it in the morning before getting dressed. I was pleasantly surprised by its smell. How much did you say it was?' £40. 'Is that the going price for a good self-tan?'
The science bit: as well as DHA, it contains an ingredient called erythulose which helps to prolong the colour, plus sesame and corn oil to hydrate and smooth skin.

Helena Rubinstein Golden Beauty Sun Tan Express Crystal Self-Tanning Gel £18 for 50ml
This facial self-tan has a light, non-sticky gel texture, which went down well with our testers - 'It doesn't feel like you are going to make a mistake with a gel somehow,' said Laura (29), 'it must be psychological' - and seemed to give the speediest results; our two testers found that it developed in under an hour, which is impressive. 'I've always used this brand for self-tanners,' wrote Lottie (39). 'The shade is perfect. I've got quite fair skin and it just makes it look a bit warmer, and I think the colour is more natural than most self-tans because it's so subtle. It looks so fake when it's too dark and it makes you look ridiculous. It's also got a really lovely sunshine holiday smell to it.'
The science bit: as well as tanning ingredients, it contains micro-reflectors to enhance the look of skin and even out its tone, and antioxidant vitamin E.

L'Oréal Sublime Bronze Multi-Position Anti-Streaking Self-Tanning Spray £9.99 for 125ml
All the testers who tried this self-tan for us - or had used it in the past - said they thought it was brilliant, mainly because it allows you to reach the parts that most fake tans don't because it is a spray. 'I only use self-tan on my face and sometimes my legs, but never the rest of my body,' wrote Kate (42). 'This is partly because I can't get there without my husband's help, and even then I worry that it hasn't gone on evenly. This was a real test to see if I could apply it all-over myself. You do need a mirror - and you have to be a bit of a contortionist to see what you're doing, and you need to wear a shower cap if you've got long hair, but I have to say the effects were very, very even. I was amazed at myself. And the tan is a good, natural colour.'
The science bit: contains alpha hydroxy acids (AHAs) which exfoliate skin - the idea being that the smoother your skin the more even the tan.

St Tropez Whipped Bronze Self Tanning Mousse £20 for 4oz
St Tropez revolutionised the self-tanning business when they introduced their salon tanning treatment - with its unique application system - a decade ago. No surprise then that St Tropez is now synonymous with serious celebrity fake baking. 'I've never had the salon treatment but have read so much about it,' wrote Tamsin (32). 'I probably could do with a bit more practise at applying it. But the effects were fantastic, you can understand what all the fuss is about, and it lasted incredibly well - for at least five or six days. I'd love to buy this product.' Other bonuses: it doesn't smell and dries in about a minute. Our tip: wear plastic gloves or scrub your hands well after application.
The science bit: the updated formula contains aloe leaf juice and alpha hydroxy acids (AHAs) to limit streakiness and make the colour deeper and longer-lasting.