How much?
Zinc oxide is a physical blocker and works as soon as you apply it. Since Arc Gentle contains 25% zinc oxide, the amount needed is generally less that with chemical products. 
Use a quarter of a teaspoon for your face, and about 1.5 ounces to cover your body. Apply the sunscreen, covering your skin evenly, especially those easy-to-skip areas like your ears, neck, eyelids, and hands.

How often?
Arc Gentle is water-resistant for 40 minutes and sweat-resistant. Apply a layer after you towel off or whenever you feel the zinc has been removed.

We are as transparent as possible and only add ingredients to our formula that are necessary. Here is the complete list of ingredients:

• Aqua
  Water
• Zinc Oxide
  Non-nano zinc oxide, 25%w/w
• Coco-caprylate/caprate
  An ingredient obtained from coconut that helps the skin to repair itself.
• Glycerin
  A natural moisturizer that’s also in our skin.
• C9-15 alkane
  Natural fatty acids
• Simmondsia chinensis (Jojoba) seed oil
  Jojoba is a drought-resistant evergreen shrub native to South-western North America. It's known and grown for jojoba oil, the golden yellow liquid coming from the seeds (about 50% of the weight of the seeds will be oil). Jojoba oil moisturizes the skin and makes it soft and supple.
• Polyglyceryl-3 Polyricinoleate
  A plant based ingredient that helps water to mix with oil.
• Cera alba (White Bees Wax)
  It's a natural material produced by honey bees to build their honeycomb.
• Polyhydroxystearic acid
  Helps to distribute the pigments nicely and evenly on the skin.
• Maltodextrin
  It's a little helper ingredient coming from corn, rice or potato starch that can help to keep skin mat (absorbent), to stabilise emulsions, and to keep the product together (binding).
• Isostearic acid
  A liquid fatty acid great for the stabilization of mineral particles in oils.
• Cetyl phosphate
  Is a good emulsifier choice for stable water-resistant sunscreen formulas.
• Tocopherol (Vitamin E)
  An antioxidant
• Disodium EDTA
  A common stabiliser in cosmetic products.
• Propanediol
  Propanediol is a natural alternative for the often used and often bad-mouthed propylene glycol. It's produced sustainably from corn sugar and it's Ecocert approved. It's quite a multi-tasker: Can be used to improve skin moisturization, as a solvent, to boost preservative efficacy or to influence the sensory properties of the end formula.
• Phenylpropanol
  A naturally occurring floral component with a delicate scent that can mask the odor of other raw materials but is not noticeable in the final product. It also has remarkable antimicrobial and preservative boosting abilities.
• Caprylyl glycol
  It’s a handy multi-tasking ingredient that gives the skin a nice, soft feel.
• Ethylhexylglycerin
  A natural preservative
• Sodium chloride
  Sodium chloride is the fancy name of salt. Normal, everyday table salt.