Oh the risks I take for you… this year I am going to make my own sun block. If I end up looking Methuselah you will be to blame….

Why Sunscreen

Sunscreens help prevent the sun’s ultraviolet (UV) radiation from reaching the skin.

There are two types of ultraviolet radiation, UVA and UVB

  • UVB is the chief cause of sunburn and linked to sun cancer.
  • UVA rays, penetrate the skin more deeply, and contribute to photoaging. They do not primarily cause sunburn but are also linked to some types skin cancer

Which Cream

You need a cream that protects from both. Creams protect in following ways

  • Physical sunscreens reflect the sunlight
  • chemical sunscreens absorb UV light


SPF factors only measure protection against UVB

  • SPF 15 blocks 93% (approx) of UVB rays.
  • SPF 30 97%
  • SPF 50 98%

When To Wear

There may be no indications of damage being done

Anyone over the age of six months should use a sunscreen daily.

Windows,filter out UVB but not UVA rays.

Up to 40 percent of the sun’s ultraviolet radiation reaches the earth on a completely cloudy day.

Shade and protective clothing are the best ways to protect infants from the sun.

Sun Block Chemicals

  • UVB (290-320nm): Aminobenzoic Acid (PABA), Cinoxate, Dioxybenzone, Ensulizole, Homosalate, Octocrylene, Octinoxate, Octisalate (Octyl Salicylate), Oxybenzone, Padimate O, Sulisobenzone, Trolamine Salicylate, Titanium Dioxide, Zinc Oxide
  • UVA (320-340nm): Dioxybenzone, Ecamsule (Mexoryl), Helioplex, Meradimate, Oxybenzone, Sulisobenzone, Titanium Dioxide, Zinc Oxide
  • UVA (340-400nm): Avobenzone, Zinc Oxide

Physical blockers like Titanium Dioxide and Zinc Oxide may give some deeper skin tones a white cast (as they are, literally, physically blocking the rays). Some may be allergic or sensitive to chemical sunscreens and may need to opt for physical blockers instead. Physical blockers protect skin by deflecting or blocking harsh UV rays, while chemical blockers/sunscreens usually absorb them. (Most other sunscreen ingredients beyond titanium dioxide and zinc oxide are chemical sunscreens, for reference.) Physical blockers tend to be more stable, while chemical sunscreens may degrade and are often paired with other sunscreen ingredients to increase stability. (See more information at


Sunscreens are unlikely to be fully effective after 2 hours

According to the skin cancer organisation  “you need to apply 1 oz – about a shot glass full. Studies show that most people apply only half to a quarter of that amount, which means the actual SPF they have on their body is lower than advertised. During a long day at the beach, one person should use around one half to one quarter of an 8 oz. bottle. Sunscreens should be applied 30 minutes before sun exposure to allow the ingredients to fully bind to the skin. Reapplication of sunscreen is just as important as putting it on in the first place, so reapply the same amount every two hours. Sunscreens should also be reapplied immediately after swimming, toweling off, or sweating a great deal.

Making Sun Block At Home

You can add active ingredients to home made, ready bought lotions or straight to a base oil such as coconut oil.

Easily Obtained Active Ingredients

Zinc Oxide is the most easily obtained and can be bought from numerous online stores. This is what I use in my sunblock creams. I have been using this for years, all over the world. I have found to prevent burning even in the most tropical of places. It is easy to use.


Offers both UVA and UVB protection

It is a physical sun block. “When you apply zinc oxide sunscreen the particles are said to stay on the outermost layer of your skin, where they scatter and absorb ultraviolet radiation, protecting your living skin below. Zinc oxide is considered a broad spectrum blocker, protecting skin from UVA, UVB and UVC.” from the website.

It is one the oldest and most effective sunblocks BUT it can sit on the skin like a white, pasty mask.

It can be added to

  • home made or ready made lotions
  • Oils like coconut oil

Nano Zinc?

There are 2 kinds of zinc – normal and nano. Nono zinc particles are tiny and so tend to reduce the white look BUT there are some concerns….

Nano or micronized zinc oxide is zinc oxide that  has been ground to a very fine powder to reduce the size of its particles. Anything with a particle size smaller than 100nm is considered a nano particle. This means it spreads more easily and does not leave a white sheen on the skin.The worry is that the particle may enter the body.

The zinc I use does leave a slight white sheen so is obviously not nano zinc. I live with the sheen.

It can also leave white marks on dark clothes. Wear white linen is the obvious answer to this.

Using Zinc


20% zinc oxide  will give an approximate SPF of 30. That is by weight. So you weigh your base say 100g of cream then you add 20% or 1/5th of zinc. Which is 20g of zinc.
You can see from the ratios below that SPF 15 is not half of SPF 30 so you cannot use that scale to work out your SPF factors.
  • SPF4 filters out 75% – 25% UVB gets through
  • SPF10 filters out 90% – 10% UVB gets through
  • SPF15 filters out 93% – 7% UVB gets through
  • SPF25 filters out 96% – 4% UVB gets through
  • SPF30 filters out 97% – 3% UVB gets through
  • SPF50 filters out 98% of UVB rays and SPF100 99%.
  • Source

These ratios were taken from DIY Natural. They have not been tested in a lab proceed with caution!

  • For SPF 2-5: Use 5% zinc oxide
  • For SPF 6-11: Use 10% zinc oxide
  • For SPF 12-19: Use 15% zinc oxide
  • For SPF >20: Use 20% zinc oxide
Sub Tan Lotion.
Add zinc to a home made or store bought cream to make a lotion
Do note that this will make your lotion makes it thicker and much whiter. Too much and you end up with clown makeup. Use a thin lotion as a base.
If you want to make a lotion there are some recipes here.
Store bought lotion. I have never tried this but apparently it helps if you warm them first – let me know how you get on!
This is best for day wear.
Sub Tan Oil
My preferred option is to add zinc  to neat oils and butters. I use my home made shea body butter as a base because it doesn’t go hard in colder climates, is easy to spread and stays in place.
Oil based sunscreens seem to stay on longer in water so is better for the beach but it does look a bit shine and oily for normal day wear.


There are claims that certain oils like coconut oil have a natural SPF. This may well be true but I strongly advise you do not rely on this alone.

Many recipes on line suggest adding essentials oils. In my opinion

  • there is no real benefit to be derived from this;
  • they may make your skin more sensitive to light;
  • essential oils are resource hungry, have a large environmental footprint and should only be used on special occasions.

None of the above has been tested in lab and you have no accurate way of knowing  what SPF your lotion has. Proceed sensibly!

Self Tan

If you want your lotion to be self tanning as well you might want to add some DHA


NB the above products come in a plastic bags – booo… but the bags are polythene so easily recycled  and as I get huge amounts cream out of one small bag of ingredients, I consider it a worthwhile compromise.



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8 thoughts on “Sun block

  1. I have a plastic free sun tip. Drink lots of tea and other things high in antioxidants! I gave up soda and now drink lots of iced tea (I’m talking at least a litter a day) and now I don’t get sunburns or they only last a day.

    This is saying a lot because I’m VERY fair skinned and burn very easily. Last summer I didn’t have any sun burns! This year I got one when gardening but it lasted under 24 hours.

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