My Big Brother likes to use Sunblock when he Cuts Grass ,, works in the Garden, or goes Fishing!!! But it does not work when the SPF number is too Low,, Instead the UV bounces around inside insuring a good burn or Tan ... He always puts it on Four or Five times when we are on the Water Fishing --- He says It is all he can find in the stores -- SPF 15 to 30 will not prevent a sunburn!! When a Person reaches 65 or 70 Skin Cancer becomes an Issue as You have what Bro calls Thin Skin. Most sunblocks say to reuse because Perspiration and water reduces the Effectiveness ... I Refuse to Buy the Junk.. Girley types want to lay out in the Sun Like Beached Whales wanting a Tan !!!! They want the low numbers and it sells better than Corn on the Cob. I have been using SPF 85 made by Neutrogena,, Ultra Sheer Dry Touch Sunblock. It is not Greasy and I put it on once before we get on the Water.. The tube was starting to get low so I asked the Wife to go on-Line to Amazon and get some more... She Has A Amazon Prime account where there is no Shipping ==== Useful -- She has More on the way and One New Tube With a SPF number of 100.... If Your sunblock dont work Complain to Store Managers or Bypass the Problem and Go On Line and get something that will work ====