How do I utilise a sun stick?

Sunscreen sticks are highly favoured as they provide a handy sun protection solution, particularly during journeys. However, many individuals are not acquainted with the best application methods that guarantee full SPF coverage with these products. The majority of these sunscreens often have very small packaging footprints that arguably make it challenging for the average user to determine precisely how much sunscreen has been applied to their skin. Sunscreens are the cornerstone of sun protection under one most crucial rule - the correct application. The requirement for a sun stick is that it should be applied in a much more meticulous manner than a casual swipe across the skin.

A roughly one ounce (approximately 28 grams) measure is suggested for the application of the sunscreen to cover the entire body, with about a five pence-sized amount for the face alone. With this, it is ensured that the quantity of application provides the protection warranted by the SPF level. For a sunscreen stick, the challenge is that it's very much possible to underestimate how much would be required for covering everything adequately. Each pass of the stick doesn't necessarily equate to a layer of full coverage, and there's a genuine risk of incomplete coverage, particularly along those tricky boundaries, like hairline and eyebrows.

It's crucial to understand that a mere couple of swipes won't suffice for comprehensive coverage. This method of application plays a significant role in determining the efficacy of the sunscreen on the skin. Research on sunscreen usage has indicated that typically a minimum of four applications of the sunscreen stick onto the skin's surface will ensure coverage. However, this cannot be universally applied as it largely depends on the sunscreen's formula and the skin's texture.

To utilise the sunscreen stick correctly, one should apply the stick gently over the skin, in strokes, covering the areas of the skin most exposed such as the forehead, cheeks, nose, and chin. Additionally, do not overlook the often-neglected areas - ears, neck, eye contour and beneath the chin. With each area of application, build up additional coverage. Overlapping strokes are advisable as they ensure that no area will be overlooked while guaranteeing even coverage over the skin.

Stick formulations typically range from drier to thicker consistencies. If the stick feels dry or pulls on the skin, then less product may be transferred, even with multiple applications. Some formulas glide over the skin so effortlessly that ample applications can be achieved in a single stroke. An additional advantage in coverage can be gained from remembering to apply pressure on the skin after each application, aiding the product to absorb and distribute evenly.

It is also of utmost importance to reapply the sunscreen stick every two hours or immediately following swimming or perspiring. The sunscreen stick is water-resistant, but with towel drying or exposure in water, it diminishes more rapidly. The correct reapplication of sunscreen should be deemed as crucial as the initial application. A hasty swipe here and there will not suffice when it comes to maintaining sufficient sun protection throughout the day - you need to apply the stick patiently and meticulously in the same manner as the first time. The same rule applies if individuals opt to use the sunscreen stick for reapplication, after applying a different cream or lotion prior to swimming or venturing outdoors. With this method, you should maximise the effectiveness of your sunscreen stick in shielding your skin from harmful UV rays.

The disparities in sun protection afforded by various application methods have been explored in a recent study published in the International Journal of Cosmetic Science. This in vitro study investigates the impact of application techniques on the efficacy of sunscreen sticks. Owing to their waxy solid components, sunscreen sticks necessitate different application methods compared to creams or sprays, making uniform and adequate coverage more challenging. The study revealed that the quantity of product deposited on the skin surface is contingent on the number of to-and-fro passes applied during use. A single stroke was insufficient to ensure a uniform protective layer, resulting in SPF values significantly lower than those indicated on the product. A minimum of four to-and-fro strokes, equivalent to approximately 0.75 mg/cm², were needed to allow a more precise comparison with the conditions of the laboratory SPF tests.

Furthermore, the pressure applied during application determined the thickness and uniformity of the film. To aid the assessment of a product's effectiveness by end users in outdoor environments, the researchers set out to create and validate a protocol involving multiple passes in various directions, with SPF measured using a hybrid diffuse reflectance spectrometry (HDRS). The results highlighted that user behaviour is crucial for the effectiveness of photoprotection using sunscreen sticks and proposed that application instructions should specify the number of strokes users need to make to apply a sufficient amount of product to achieve the intended UV protection at recommended levels.

• COIFFARD L. J. M. & al. Adaptation of the protocol for determining in vitro the sun protection factor of anti‐solar sticks. International Journal of Cosmetic Science (2008).

• UNICE K. & al. Factors that influence sunscreen application thickness and potential preservative exposure. Photodermatology, Photoimmunology & Photomedicine (2015).

• ARAÙJO E. M. & al. Analysis and characterization of stick sunscreens available in the Brazilian market. 6th Electronic Conference for the Faculty of Pharmacy Graduate Program – UFF (2024).

• NEHA P. & al. Formulation and development of sunscreen stick by calendula oil. Journal of Biotechnology and Food Engineering (2024).