Is it really 50? From what Ive read (and cannot link) there seems to be disparity between the numbers. 

The current AU/NZ standards basically define anything with a mean SPF of >60 to be labelled SPF50+. The effective difference between 50 and 100 is so low as to be meaningless in typical usage (something like 98% vs 99% effectiveness).

Geektastic: Thinking about it, we always used to be able to buy “Sun Block” which was purported to be 100% but I’ve not seen that here either.

We don't lead the world in UV.

A good paper on global UVI - by our own NIWA (Liley & McKenzie) is here:
https://niwa.co.nz/sites/niwa.co.nz/files/import/attachments/Liley_2.pdf

But kiwis do need a good sun-block - as we're mostly pale, outdoors a lot and have significant UV.

50 SPF is supposed to give you a 50-fold reduction in burn/damage.
Hence, a burn after 12 minutes would be pushed back to 10 hours.

But apparently any suncreen's effectiveness expires after a couple of hours...
Even if you apply the correct amount - 2 to 4 times what the average person actually uses.

So I guess an SPF greater than 50 doesn't win you much unless you are way more sun-sensitive than average.

Geektastic: Thinking about it, we always used to be able to buy “Sun Block” which was purported to be 100% but I’ve not seen that here either.

Odd that a difference in spf of 50% only equals a 1% increase in effectiveness. Sounds like a poor scale.

Labelling regulations, the term “sunblock” is misleading and not permitted because it may be interpreted to mean that 100% of the sunburning radiation is blocked. No sunscreen offers 100% protection.

Remeber Linda Hamilton in the Terminator movies?  She said that if you didn't have 10,000+ suntan lotion you would fry when Skynet took over.

We can't buy that either.

Maybe overseas is like farenheit, and here is like celsius, where 50 is actually 100 :) 

Geektastic: I’ve seen it overseas, but here it never goes beyond 50. Why?

neb:

Geektastic: I’ve seen it overseas, but here it never goes beyond 50. Why?

Because we have truth-in-advertising laws. There's not much point to anything rated above 50, it's more important that you reapply your 50 regularly than that you use SPF6000 to get that extra percent or so of protection.

There is an Australian and New Zealand standard for suncreen product evaluation and classification (AS/NZ 2604), see page 7-98 of the preview

https://www.standards.govt.nz/shop/asnzs-26042021/

tldr; error/variance in spf measurement across labs due to quality of simulated uv is one reason SPF was limited to 30 then later raised to 50, also beyond 50 is well into diminishing returns and pretty much purely for marketing gain only

Haven't heard of 100SPF before, that sounds like something Dulux could sell you.

decibel:

 

Remeber Linda Hamilton in the Terminator movies?  She said that if you didn't have 10,000+ suntan lotion you would fry when Skynet took over.

 

 

 

We can't buy that either.

 

I am printing this reply out and framing it, because it is by far the best comment I've ever seen on Geekzone.

Ragnor:

 

There is an Australian and New Zealand standard for suncreen product evaluation and classification (AS/NZ 2604), see page 7-98 of the preview

 

https://www.standards.govt.nz/shop/asnzs-26042021/

 

tldr; error/variance in spf measurement across labs due to quality of simulated uv is one reason SPF was limited to 30 then later raised to 50, also beyond 50 is well into diminishing returns and pretty much purely for marketing gain only

 

 

 

When I was younger growing up in Australia the standard only went as far 15+. Back then it was noticeable that some 15+ brands were more effective than others but you would only find out through trial and error as the labelling only allowed 15+ to be claimed. As above it was later raised to 30+ and then again to 50+.