Formulating with Aloe Vera Gel Base and Sunscreen Ingredients

Let's address your questions regarding formulating with the Aloe Vera Gel (Heavy) base and incorporating sunscreen ingredients.

Adding Water to Aloe Vera Gel (Heavy)

The Aloe Vera Gel (Heavy) base already contains a high percentage of purified water (over 92%). It is an oil-free gel base designed to be mixed with other ingredients. Adding more water will primarily reduce the viscosity, making the gel thinner.

However, if you are adding oil-based or silicone-based ingredients (like some sunscreen dispersions or emollients) along with water, you will likely need an emulsifier to create a stable mixture and prevent separation. The Aloe Vera Gel (Heavy) base itself is not an emulsion and won't inherently emulsify oil and water phases.

Adding Titanium Dioxide and Zinc Oxide for SPF 50

Achieving a specific SPF level like 50 requires careful formulation and testing. Simply adding a certain percentage of sunscreen actives does not guarantee a specific SPF, as it depends on the specific type of Titanium Dioxide and Zinc Oxide used, their dispersion quality, and the overall formula composition.

For broad-spectrum protection (UVA and UVB), it is recommended to use both Titanium Dioxide and Zinc Oxide. The Zinc Oxide 35nm Liquid is designed for sunscreen formulations and can be used at 5-40% (with active Zinc Oxide not exceeding 25% according to FDA law). The Titanium Dioxide 200nm EasyDisperse™ is noted as being primarily for make-up products, and for dedicated sunscreen, other grades might be more suitable. Typical usage rates for Titanium Dioxide in sunscreens can also range widely, often up to 25% or more depending on the grade and desired SPF.

To reach SPF 50, you would likely need high concentrations of both ingredients, potentially in the range of 15-25% or more total active sunscreen material, but this must be confirmed by SPF testing of your final formula.

Addressing Texture Issues (Difficult to Spread, Powdery, Thick)

The texture issues you described (difficult to spread, dry, powdery, thick) are common when incorporating high levels of physical sunscreen powders or dispersions into a base, especially if the base is primarily water-based and oil-free like the Aloe Vera Gel (Heavy).

Physical sunscreens like Titanium Dioxide and Zinc Oxide are powders. When added at high concentrations, they can make the formula feel dry and powdery, particularly if they are not well-dispersed or if there aren't enough emollients or oils in the formula to provide slip and spreadability.

To improve the texture:

• Ensure Proper Dispersion: Make sure the Titanium Dioxide and Zinc Oxide are fully and evenly dispersed in a suitable medium (often an oil or silicone phase) before adding them to the gel base.
• Adjust Oil/Emollient Content: Incorporate emollients or oils into your formula. These ingredients help to lubricate the skin, improve spreadability, and reduce the dry, powdery feel caused by high levels of powders. You might need an emulsifier to stably combine these oils with the water-based gel.
• Consider an Emulsion System: Instead of adding sunscreens to a gel base, formulating a proper oil-in-water or water-in-oil emulsion might provide a more stable and pleasant texture when using high levels of physical sunscreens.
• Reduce Solids/Thickeners: If the cream is too thick, you may need to reduce the total percentage of solid ingredients (like the sunscreen powders) or the gelling agent/thickener in the formula. Simply adding water without an emulsifier might lead to separation or worsen the powdery feel if there are oil/silicone components present.

Adjusting the formulation to include compatible emollients and potentially using an emulsification system will help create a smoother, more spreadable texture and reduce the powdery residue.