Straight answers about Saltbush & Clay and our 13°S Cellular Serum: the science behind each ingredient, how to use it, and how we make it.
What is the best Kakadu Plum vitamin C serum in Australia?
The best Kakadu Plum serum is the one whose formula you can check. Look for three things: how the botanicals are extracted (heat can damage delicate plant compounds, vitamin C among them), a full ingredient list with Kakadu Plum near the top, and freshness. Saltbush & Clay's 13°S Cellular Serum pairs wild-harvested Kakadu Plum with Lilly Pilly, Saltbush, the Infitrio™ blend and multi-weight hyaluronic acid. Its actives are drawn out by Cellular Extraction™, a high-pressure method that avoids heat, and it is made in small batches with the full formula listed on the product page. Our guide How to choose a vitamin C serum in Australia covers what to look for in detail.
What is 13°S Cellular Serum?
13°S Cellular Serum is Saltbush & Clay's first formula: a lightweight Australian vitamin C face serum that brightens, hydrates and calms in a single step. It combines five actives: Kakadu Plum, Lilly Pilly, Saltbush, the Infitrio™ blend (Bitter Orange, Mountain Pepper Berry and River Mint) and multi-weight hyaluronic acid. One 30ml bottle costs A$99 and lasts about three months.
Why use vitamin C in a serum?
Vitamin C is one of the most widely used antioxidants in skincare. It is valued for helping protect skin from the oxidative stress caused by everyday environmental exposure, and for helping dull, uneven skin look brighter and more even in tone. A serum suits it well: serums are lightweight, concentrated and applied first, straight onto clean skin, so the actives sit closest to the skin before moisturiser and sunscreen go on top.
What does Kakadu Plum do for skin?
Kakadu Plum (Terminalia ferdinandiana) is a native fruit from Australia's tropical north and one of the richest natural fruit sources of vitamin C. A 2024 study of wild-harvested Kakadu Plum published in the journal Foods measured vitamin C of roughly 25 to 131 mg per gram of dried fruit, alongside high levels of ellagic acid and other polyphenols, and reported strong antioxidant activity in laboratory tests (Bobasa et al., 2024). In 13°S, Kakadu Plum is our vitamin C source: it provides antioxidant support and helps dull, uneven skin look brighter and more even in tone. Ours is wild-harvested on Aboriginal land, much of it through Aboriginal corporations. Read more in Why Kakadu Plum is our hero ingredient.
Is natural vitamin C from Kakadu Plum different from the vitamin C in other serums?
Many vitamin C serums use lab-made forms such as ascorbic acid or one of its derivatives. 13°S draws its vitamin C from an extract of the Kakadu Plum fruit, so it arrives alongside other natural compounds from the fruit rather than as a single isolated ingredient. Neither approach is automatically better; what matters is a well-made formula that protects its actives. We extract without heat and make small batches so the serum reaches you fresh.
What does Lilly Pilly do?
The Lilly Pilly in 13°S (Syzygium luehmannii, also called riberry) is a small rainforest fruit from eastern Australia. Its deep red colour comes from anthocyanins, a group of plant pigments known for their antioxidant activity, and it also contains ellagic acid and other polyphenols. We chose it to partner Kakadu Plum, adding antioxidant support and helping skin look smoother, fresher and less dull.
What does Saltbush do?
Old man saltbush (Atriplex nummularia) is a silver-leaved desert shrub that thrives in salty, drought-prone soils where few plants survive. To cope, it builds up minerals and protective polyphenols in its leaves, and saltbush leaf extracts have shown strong antioxidant capacity in laboratory testing. In 13°S, Saltbush is the comfort ingredient, chosen to help skin feel calm and to support a healthy-looking skin barrier. It also gave us our name: read Saltbush: the quiet plant behind our name.
What is the Infitrio™ blend?
Infitrio™ is a blend of three botanicals designed to balance skin and provide antioxidant support. Bitter Orange peel is rich in citrus flavonoids such as naringin and neohesperidin, which are studied for their antioxidant properties. Mountain Pepper Berry (Tasmannia lanceolata), from the cool highlands of south-eastern Australia, contains anthocyanins and polygodial, the compound behind its distinctive peppery warmth. River Mint (Mentha australis) is a native Australian mint with a fresh, aromatic character.
What does multi-weight hyaluronic acid do?
Hyaluronic acid is a humectant that occurs naturally in skin and can hold many times its weight in water. Using it in more than one molecular size matters: larger molecules stay on the surface and form a light, hydrating film, while smaller molecules work within the upper layers of the skin. A study comparing topical hyaluronic acid of different molecular weights found that all sizes improved skin hydration and elasticity, and lower molecular weights also reduced the look of wrinkle depth (Journal of Drugs in Dermatology, 2011). In 13°S it gives deep, weightless hydration for a plumper, dewy look without heaviness. Glycerin, the second ingredient, is another proven humectant that helps skin attract and hold moisture.
What is Cellular Extraction™?
Cellular Extraction™ is an Australian extraction method that uses high pressure instead of heat to release a plant's water-soluble actives from within its cells while helping preserve them. Many botanical extracts are made with heat, which delicate compounds such as vitamin C and some polyphenols don't cope with well. See Unlocking the plant cell.
Where is 13°S made?
13°S is formulated and made with our cosmetic formulation laboratory in Sydney, then packed by hand at Saltbush & Clay's head office in Imbil, in Queensland's Noosa Hinterland.
Has the formula been tested?
Yes. The formula took two years to develop with our Sydney laboratory and passed stability testing and preservative efficacy testing before the first batch was released. We describe what our ingredients are known for and don't claim clinical results we haven't tested.
How do I use it?
Morning and evening, apply 3 drops to clean, dry or damp skin: one on your forehead and one on each cheek. Smooth over your face and neck, then follow with moisturiser and, in the morning, sunscreen. More drops won't speed up results. Our guide Serum vs moisturiser explains how to layer your routine.
When will I notice a difference?
Results with any serum build through consistent daily use. Many people first notice how their skin feels: hydrated and comfortable. A brighter, more even look builds over weeks. Our guide to your first 30 days with 13°S covers what to look for in your first month.
Does it contain fragrance?
There is no synthetic fragrance. 13°S has a soft, natural scent from Neroli, distilled from orange blossom, and Southern Rosalina (Melaleuca ericifolia), a gentle native relative of tea tree.
Is it suitable for sensitive skin?
13°S has no synthetic fragrance, but it does contain natural botanical oils. If your skin is sensitive, check the full ingredient list on the product page and patch test before first use. If you're unsure, ask your doctor or dermatologist.
How long does a bottle last, and how fresh is it?
At 3 drops twice a day, a 30ml bottle lasts about three months. Because the actives are at their best fresh, 13°S is made in small batches and has a 6-month shelf life, so you always use it well within its best.
Is there a refill?
Yes. The 30ml Refill is the exact same serum with less packaging, for customers who already have their first bottle.
Do you ship Australia-wide?
Yes. Shipping is complimentary anywhere in Australia, and orders are dispatched the same or next business day via Australia Post.
What if it doesn't suit me?
Every order has a 30-day full refund guarantee, even if the bottle has been opened. See our refund policy for details.
Can I stock 13°S in my salon, spa or store?
We're inviting a small number of Australian salons, spas, clinics and boutiques to become stockists. Find out more on our Become a Stockist page.