Biome CastorBub™

Versatile for all ages

Baby
Baby bottoms at nappy change, cheeks prone to dryness or wind, skin folds that need comfort and protection.

Chafing or skin folds
Anywhere prone to rubbing or moisture (like inner thighs, underarms, under the bust) — zinc oxide works well to reduce irritation and create a protective layer.

Sports or outdoor use
Runners, cyclists, or hikers sometimes use zinc balms to prevent chafing in friction areas. It also works well for sweat-prone areas that get sore in heat or humidity.

Dry patches
While not a replacement for a daily moisturiser, it helps hydrate and lock in moisture to allow irritated dry spots to recover e.g. elbows, knees, rough heels.

Skin protection
For adults with sensitive skin and continence needs who want to avoid petroleum products, a balm like CastorBub can be helpful for dealing with prolonged dampness or friction, keeping the skin comfortable and protected.

What makes CastorBub special

Barrier protection: Zinc oxide forms a physical layer on the skin to help prevent nappy rash by shielding against moisture and friction.

Moisturising & soothing: Castor oil and shea butter condition and soften skin, helping to keep it supple.  A big part of nappy rash agony is the baby’s discomfort – crying at nappy changes or when urine hits the rash.  CastorGuard creates a soothing sensation upon contact.

Gentle on delicate skin: Formulated with simple, natural ingredients that are safe for newborns and sensitive skin.

No nasties: Free from petroleum, synthetic fragrances, parabens, and artificial additives - learn more on those below.

Australian made: Crafted in small batches, supporting local.

The ingredients

Castor oil (hexane-free): The hero ingredient. Rich, smooth, and highly moisturising. Helps lock in hydration while supporting a protective barrier.

Zinc oxide (non nano): A mineral powder that creates a breathable shield, and leaves a slight white tinge on the skin. Zinc oxide works because it protects, dries, soothes, and defends all at once.  Helps prevent worsening and creates the conditions for the skin to heal naturally.  

Apricot kernel oil: Lightweight and easily absorbed, nourishing without greasiness.

Shea butter: Deeply conditioning, adds soothing comfort.

Carnauba & candelilla waxes: Provide a protective texture while remaining vegan-friendly.

FAQ: Nappy rash cream & barrier balms

1. How does a barrier cream help prevent nappy rash?
Barrier creams work by creating a thin, protective layer over your baby’s skin. This shield helps keep moisture, urine, and irritants from sitting directly on the skin, which reduces friction and prevents redness from developing into a rash. A good barrier cream also locks in natural moisture to support healthy skin recovery.

2. How do I apply nappy rash cream correctly?
Gently clean and pat your baby’s bottom dry before applying. Use a thin, even layer of cream with clean hands at each nappy change, especially before longer sleeps. Focus on the creases and folds where moisture can get trapped, but avoid applying too thick a layer, as the skin still needs to breathe.

3. Can I use nappy rash cream on other areas?
Yes, you can use nappy rash cream on other spots prone to dryness or irritation. It can help soothe chapped cheeks, dribble rash under the chin, or dry patches on knees and elbows. Always check the ingredients first, and do a small patch test on sensitive skin.

4. What is the safest bottom balm?
The safest choice is a natural bottom balm made without petroleum, parabens, synthetic fragrances and preservatives. Look for formulations with zinc oxide for protection, plus soothing plant oils and butters. These natural ingredients are gentle enough for newborn skin, while still providing an effective barrier against moisture. 

5. Is CastorBub vegan and cruelty-free?

Yes!  We personally make CastorBub bottom balm in the Biome lab in Brisbane. Many bottom balms contain beeswax and lanolin from sheep's wool. CastorBub is vegan and not tested on animals.

What are the synthetics in conventional barrier creams?

Most barrier creams rely on synthetic additives to create texture, extend shelf life, or reduce manufacturing costs. While effective at forming a protective layer, these ingredients concern those who want to avoid unnecessary chemicals.  Some of the ingredients surprisingly found in popular baby nappy rash creams:

• Petroleum: Paraffinum Liquidum (mineral oil), Liquid Paraffin, Paraffin Wax, Microcrystalline Wax – inexpensive occlusives that form a barrier, but no natural nourishment & not biodegradable.
• Silicones: Dimethicone – synthetic polymers that coat the skin for smoothness, but do not feed or support skin health.
• Synthetic waxes: Synthetic Beeswax – lab-made substitutes 
• Petrochemical glycols: Ceteareth-25 and Propylene Glycol
• Preservatives: Methylparaben, Sodium Benzoate, Benzyl Alcohol – extend shelf life but are often avoided by parents concerned about sensitivity and potential hormone disruption.
• Fragrance-related compounds: Benzyl Benzoate, Benzyl Cinnamate, Linalyl Acetate – provide scent but are common irritants for sensitive skin.

Learn more here about how CastorBub compares with conventional barrier creams.

Don't miss our original CastorGuard with 140+ 5 star reviews.  CastorGuard is nature's Vaseline alternative - a multi-purpose petroleum-free balm. Users report it works for lip balm for dry lips, cracked heels, chafing, dry skin, dermatitis, puffy eyes, scratches, and more.  As it does not contain zinc oxide (which leaves a white tinge), CastorGuard is better for visible skin such as the face and hands.