Zinc Oxide

Zinc oxide (ZnO) is a white inorganic powder with unique properties that make it useful both in cosmetic and makeup applications and in polyurethane resin formulations. Odourless, non-flammable and breathable, it is a versatile material that any special effects, makeup or composites workshop can take advantage of on multiple fronts.

Technical specifications

What it is used for

Zinc oxide has a very wide range of applications. In the workshop, its two main uses are body and artistic makeup, and the modification of polyurethane resins as a functional additive:

• Mattifier and setting agent for full-body makeups in theatrical, film and television productions
• Oil absorber for skin with seborrhoeic tendencies
• Opaque white pigment for makeup and artistic painting
• Protective and finishing layer over already applied makeup, without clogging pores
• Additive in polyurethane resins to optimise the curing process
• Improvement of mechanical and thermal properties in polyurethane parts
• Reduction of bubbles and surface defects in resin castings
• Increased hardness and strength in rigid or flexible polyurethane formulations
• System stabiliser in resins to extend the service life of the cured product

How to use it

In makeup and special effects

1. Apply the base or body makeup to the skin as usual.
2. Using a clean brush or sponge, pick up a small amount of zinc oxide powder.
3. Gently distribute the powder over wet or dry makeup to mattify it, absorb excess oil and set the result.
4. Remove the excess with a clean brush. The finish will be breathable and will not clog pores.
5. For a pure, opaque white, apply directly to the skin with a neutral base or as a pigment in homemade cosmetic formulations.

As an additive in polyurethane resins

1. Determine the percentage of zinc oxide to add according to the desired result (typically between 1% and 5% of the total mix weight; adjust based on testing).
2. Incorporate the powder into the polyol component (component A) before mixing with the isocyanate.
3. Homogenise thoroughly with mechanical or manual stirring until a uniform, lump-free dispersion is obtained.
4. Mix with the isocyanate (component B) at the ratio indicated by the resin manufacturer and proceed with the usual casting or laminating process.
5. The zinc oxide will act during curing, improving the final properties of the part.

Usage tips

Dosage in resin: start low

In polyurethane resins, more is not always better. An excess of filler can increase the viscosity of the mix and make casting or impregnation difficult. Start with low proportions (1–2%) and increase progressively until you find the balance between improved properties and workability. If you need to reduce viscosity while maintaining the filler load, consider combining the zinc oxide with hollow glass microspheres, which add lightness without penalising flow as much.

Homogeneous dispersion: the key to results

Zinc oxide tends to agglomerate if added directly in bulk. For correct dispersion in resin, use a paddle stirrer or laboratory disperser and mix at medium speed for at least 2–3 minutes before incorporating the second component. In cosmetic applications, sieve the powder before using the brush to avoid visible accumulations on the skin.

Storage and handling

Store zinc oxide in an airtight container, in a dry place away from moisture. Although it is neither flammable nor toxic by dermal contact at normal usage quantities, avoid prolonged inhalation of the fine powder: work in ventilated spaces or use a particulate mask (FFP2) when handling large quantities. If you are working with Gel de Sílice AT2 or other fillers in the same process, take extra respiratory precautions.

Frequently asked questions