Unlock the secret to stunning, luscious curls with the power of ceramides in hair products! Think of ceramides as the trusty sidekicks to your hair’s superhero journey – they’re the tiny but mighty defenders of moisture, strength, and overall hair happiness.
Ceramides in hair products are lipid molecules naturally found in the hair’s structure, often included in formulations to enhance the hair’s moisture retention, strengthen its integrity, and promote overall health and resilience.
Consider ceramides as essential components in hair care, playing a pivotal role in maintaining the health and integrity of each hair strand. These vital elements act to repair, strengthen, and protect your hair, ensuring it remains strong and resilient against external stressors.
To provide a deeper understanding of ceramides and their impact on hair care, we have consulted with our hair scientist expert, a cosmetic formulator with a PhD in Chemistry. This expert will guide us through the complexities of ceramides, offering insights into how they benefit your hair and how you can effectively incorporate them into your haircare routine.
Additionally, we will explore the mechanisms through which hair naturally loses ceramides over time and discuss strategies for their replenishment. We aim to highlight the types of hair that would benefit most from ceramide-enriched hair care products. Moreover, we will offer guidance on identifying ceramides in the product ingredient list, ensuring you make informed choices in selecting hair care products.
Unveiling Ceramides in Hair Products
Ceramides are specialized lipids that hold integral importance for both human skin and hair fibers. With distinct chemical properties, they play a crucial role in shaping skin morphology and hair structure.1,2,3
Imagine them as nature’s adhesive, binding the two neighboring layers of the surface together. These molecules are composed of a lengthy hydrophobic fatty chain linked to a sphingoid base through an amide bond.
This unique structure results in ceramides embodying a dual nature, possessing both hydrophilic and hydrophobic groups within the same molecule.
This distinctive composition enables them to adhere to both fatty substances and water-soluble components present within the skin and hair matrix.
Unveiling Ceramides: From Skin to Hair
Originally, the focus of ceramides was exclusively directed towards the skin; nevertheless, in more recent times, the isolation and identification of ceramides have extended to human hair as well.4
Scientific investigations have unveiled their presence beneath the cuticle layer, snugly situated within the cell membrane complex.
Despite lipids being the backstage crew, constituting just 2-6% of the total hair mass, ceramides step into the spotlight as the 10-15% stars of these lipids.5,6 Think of them as the supporting actors who steal the show.
Since their identification and isolation, dedicated hair scientists have embarked on an adventure of exploration, deciphering the treasure trove of benefits ceramides hold for hair health. It’s like they stumbled upon a new chapter in the book of follicle secrets.
Ceramides: Essential Active Ingredients for Hair and Scalp Care
Ceramides, a class of lipid molecules, assume a critical role in upholding the integrity of the skin’s barrier function. These molecules contribute to the formation of the lipid layer that securely binds the upper epidermal layer to the underlying skin strata.
Similarly, ceramides have important benefits for scalp health. They help prevent Trans Epidermal Water Loss (TEWL), effectively acting as a barrier to retain essential moisture within the scalp.
The absence of ceramides within the scalp’s epidermal structure can render the surface dry and coarse, rendering it susceptible to an array of scalp disorders.
Likewise, while lipids are acknowledged components of the hair structure, with sebum forming a protective coat that both lubricates the hair shaft and delivers essential conditioning, ceramides introduce a fascinating twist.
Instead of residing at the surface, ceramides are nestled deep within the hair’s architecture, earning them the moniker of “Internal Lipids,” ensconced within the lower layers of cuticles.
The presence of ceramides boasts far-reaching impacts on the characteristics of hair fibers,7 bestowing them with enhanced tensile strength, an alluring gloss, protection against the sun’s harmful UV radiation, and a heightened capacity for hydration.
Ceramide Depletion and Restoration: Understanding the Process
The intricate balance of ceramides within the hair and skin is pivotal for their health and vitality. As we delve into the process of ceramide depletion and restoration, we uncover the delicate interplay between external stressors and internal mechanisms that govern these lipid molecules’ presence. Understanding this process provides essential insights into maintaining optimal hair wellness.
Loss of Ceramides
Ceramides, despite their essential role, are susceptible to oxidative stress, UV-induced damage, and aggressive chemical treatments, culminating in a reduction of their presence within the hair structure.
Routine activities like shampooing, grooming, and exposure to elevated temperatures further contribute to the breakdown of ceramides, consequently compromising the strength and integrity of hair fibers.
Remarkably, even though ceramides constitute a minute proportion of the hair fiber’s overall mass, a direct relationship exists between the levels of ceramides and the mechanical robustness of hair.
Additionally, the profile of ceramide distribution reveals a decline from the hair shaft’s root to its tip, mirroring the pattern of hair damage where the tips exhibit greater wear and tear compared to the root ends.8
There exists a strategy to restore ceramide levels to their optimal state. While extracting natural ceramides proves challenging for personal care formulations, the realm of synthetic ceramides offers a solution.
Tailored in laboratories, these synthetic counterparts find their place in everyday hair care regimens, seamlessly integrating into products like shampoos, conditioners, and deep conditioning masks.
Their incorporation not only amplifies the hair’s moisture retention and mechanical strength but also elevates the overall sensory experience of hair care.
Furthermore, a cohort of analogous ceramide-like molecules, often referred to as pseudo-ceramides, stands available today, offering yet another avenue to enhance hair quality.
Enhancing Hydration and Barrier Function: The Positive Impacts on Hair and Scalp
Enhancing hydration and reinforcing the skin’s barrier function significantly benefit both hair and scalp. This tag team effort wards off dryness, brittle hair, irritation, and scalp issues while promoting healthy hair growth and overall vitality.
Enhancing Hydration and Barrier Function
Ceramides exhibit an exceptional ability to retain water molecules, making their topical application a potent strategy for rehydrating parched skin, scalp, and hair surfaces.
Empirical evidence underscores their significant role in elevating the water content of the stratum corneum, thus positioning ceramides as pivotal active agents in combatting scalp dryness, itchiness, and the occurrence of inflammatory red patches.
By addressing these concerns at their source, ceramides facilitate the cultivation of a healthier environment for hair fibers to thrive.9
Enhancing Hair Fiber Strength
Ceramides assume the role of an adhesive agent, meticulously uniting the two neighboring layers comprising the hair’s cellular matrix.
The diminishment of ceramides within this structure can precipitate a weakening of this bond, subsequently compromising the mechanical resilience of hair fibers.
Empirical validation of this phenomenon has been attained through meticulous measurements of the friction coefficient in chemically treated hair fibers, both in the presence and absence of ceramides.
Notably, the application of ceramides yielded a substantial reduction in fiber friction, facilitating smoother combing, brushing, and styling processes.10
Enhancing Cuticle Alignment and Combing Efficiency
In the field of hair care, lipids play a crucial role in enhancing lubrication and improving manageability.
Ceramides, which are integral components of internal lipids, are essential in ensuring the proper alignment, cohesion, and flattening the hair cuticles.
Cuticles serve as the outermost layer of the hair shaft and stand as the primary interface with cosmetic formulations, abrasive chemical treatments, and incoming UV radiation. Consequently, preserving the integrity of the cuticular layer emerges as a paramount concern.
Ceramides emerge as key protagonists in this narrative, contributing significantly to the maintenance of smooth, resilient, and tightly interconnected cuticles. This orchestration effectively diminishes the friction between fibers and reduces the force required for combing wet and dry hair.
Laboratory assessments have elucidated that the greatest advantages of ceramide application are reaped by damaged and chemically treated hair fibers, attributable to the heightened absorption and penetration of ceramide molecules.
Further substantiating these findings, microscopic examination of hair fibers underscores the notable adsorption of ceramides and the resultant enhancement in surface smoothness.
Revitalizing Chemically Treated Hair Fibers
The aftermath often entails hair that’s not just weak, but also dry and brittle, marked by a noticeable reduction in mechanical resilience.
Analysis of these compromised hair fibers reveals a diminished presence of ceramides, further underscoring the extent of damage. However, a promising solution emerges in the form of ceramide application.
By introducing ceramides to these chemically processed hair fibers, a multifaceted rejuvenation unfolds:
- the strength of hair fibers is reinstated.
- luster is renewed.
- the cuticle layer’s hydrophobicity is enhanced.
- the tactile sensation of both wet and dry hair is notably improved.
What Types of Hair Benefit the Most with Ceramides?
Ceramides extend their benefits across the spectrum of hair types and ethnic backgrounds, making them universally suitable. However, distinct considerations emerge for specific hair types.
Curly and African-American hair fibers, characterized by heightened porosity, coarser texture, and diminished lipid profiles, tend to exhibit marginally lower ceramide levels. This observation is substantiated by the aforementioned attributes.
In these cases, ceramides play a pivotal role by augmenting the lipid content, thereby enhancing both the physical and chemical characteristics of the hair fiber.
Moreover, hair fibers subject to aging, intense UV exposure, and rigorous chemical treatments typically showcase reduced ceramide levels within their structure.
The application of ceramides to such compromised hair fibers yields a multifaceted restoration – reinstating the hair’s natural texture, mitigating surface friction, and elevating the sensorial qualities.11
Products That Work the Best with Ceramides
The versatility of ceramides shines through as they seamlessly blend into an array of hair care products, encompassing shampoos, conditioners, hair masks, and leave-in treatments.
Rigorous scientific investigation centered around shampoos enriched with ceramides has yielded compelling evidence of notable hair quality enhancement through successive wash cycles.
This observation underscores the efficacy of ceramides, even when incorporated at low concentrations within rinse-off formulations.
Crucially, the duration of contact with hair bears a direct correlation to the depth of penetration and resultant outcomes. This principle holds particularly true for conditioners and leave-in products fortified with ceramides.
These formats afford extended interaction periods, facilitating enhanced adsorption and penetration through the hair cuticle layer. This attribute makes them particularly adept at addressing the concerns of damaged and chemically treated hair fibers.
For consumers aiming to extract maximum benefits from ceramides, a prudent approach involves experimenting with both rinse-off and leave-in applications.
This two-pronged strategy offers a comprehensive approach to harnessing the potential of ceramides for optimized hair health.
How To Identify Ceramides on Product Labels
The inclusion of ceramides in product formulations is denoted through the term “Ceramide,” a recognition acknowledged by the Personal Care Products Council, formerly referred to as CTFA, as well as the International Nomenclature for Cosmetic Ingredients (INCI).
Ceramides encompass a range of variants, each designated by a distinct number, such as:
- Sphingosine: This is a naturally occurring ceramide precursor that contributes to the health of the hair cuticle and overall hair integrity.
- Phytosphingosine: Similar to sphingosine, phytosphingosine is another ceramide precursor found in various plant-based oils, such as rosehip oil, hemp seed oil, evening primrose oil, kukui oil, sunflower oil, soybean oil, wheat germ oil, rice bran oil, jojoba oil, safflower oil, and grapeseed oil. These help support hair hydration and strength.
- Ceramide 6 II: This ceramide subtype helps maintain the skin’s barrier function and contributes to hair health by enhancing moisture retention and protecting against external aggressors.
- Ceramide AP (Ceramide 3): Ceramide AP aids in restoring the lipid barrier, which is crucial for retaining moisture and preventing hair dryness and breakage.
- Ceramide EOP (Ceramide 1): Ceramide EOP is vital for maintaining the integrity of the hair cuticle and overall hair structure, contributing to smoothness and manageability.
- Ceramide NG: Derived from safflower oil, ceramide NG helps to improve hair’s moisture retention and overall strength.
- Ceramide-2 also known as Ceramide NS (N-stearoyl sphingosine): In hair products, Ceramide-2 aids in enhancing the hair’s structural integrity, promoting smoothness, and preventing moisture loss. Its role in hair care revolves around supporting healthy hair cuticles, which in turn contributes to reduced frizz and improved manageability.
- Ceramide-5 or Ceramide AS (N-acetyl-sphingosine): In hair products, Ceramide-5 plays a similar role by enhancing the hair’s moisture retention capacity and supporting its overall strength. By fortifying the hair’s natural lipid layer, Ceramide-5 aids in shielding the hair from environmental stressors and improving its resilience, resulting in smoother and more lustrous hair.
- 2-oleamido 1-3 octadecanediol: This ceramide analog, commonly known as OLEAMIDE-3, has demonstrated significant potential for enhancing hair health. It mimics the action of natural ceramides by helping to fortify the hair cuticle and maintain the integrity of the hair shaft. By aiding in cuticle alignment and minimizing friction between hair fibers, OLEAMIDE-3 contributes to improved hair smoothness, shine, and overall manageability. It’s often incorporated into hair products to enhance the tactile and visual qualities of the hair, making it a valuable ingredient in promoting healthy-looking hair.
Please note that formulations and ingredient availability can vary across different products and brands. Always refer to the product’s ingredient list to confirm the presence of specific ceramides.
Additionally, synthetic pseudo-ceramides can be identified by their specific letter designations, as exemplified by “Ceramide NG,” “Ceramide NP,” and “Ceramide AP.”
These distinct ceramide variants exhibit variations in their chemical structures and inherent properties. Consumers are empowered to discern and recognize these ceramides effortlessly by perusing the product label affixed to the packaging.
Products with Ceramides
In this curated selection, we present a range of products infused with ceramides. We understand the value of your time, so we’ve highlighted the ceramides in each product, making it effortless for you to delve into the world of ceramide-enriched hair essentials.
To assist you in making informed decisions, we have included the ingredient lists for each product. However, please be aware that these lists might not be up to date. For the most accurate and current information, we recommend consulting the details provided on the product’s packaging. Additionally, it’s important to note the size of the product, as this can differ between retailers.
An essential addition for colored hair, this shampoo and conditioner duo features a potent combination of color-preserving agents along with a fusion of natural and synthetic ceramides. Together, they work to repair and safeguard against further damage, ensuring vibrant and enduring color results.
Shampoo Ingredients: Aqua/Water/Eau, Sodium Cocoyl Isethionate, Disodium Laureth Sulfosuccinate, Sodium Lauryl Sulfoacetate, Sodium Lauroyl Sarcosinate, Coco-Betaine, Glycol Distearate, Glycereth-26, Decyl Glucoside, Coconut Acid, Sodium Hydroxide, Parfum/Fragrance, Sodium Isethionate, Citric Acid, Ppg-5-Ceteth-20, Sodium Chloride, Divinyldimethicone/Dimethicone Copolymer, Polyquaternium-7, Amodimethicone, Polyquaternium-10, Carbomer, Acrylates Copolymer, Peg-55 Propylene Glycol Oleate, Propylene Glycol, C11-15 Pareth-7, Hexyl Cinnamal, Benzoic Acid, Laureth-9, Butylene Glycol, Glycerin, Linalool, Tocopherol, Olea Europaea Fruit Oil/Olive Fruit Oil, Camelina Sativa Seed Oil, Trideceth-12, Salicylic Acid, Helianthus Annuus Seed Extract/Sunflower Seed Extract, Sodium Benzoate, Magnesium Nitrate, Benzyl Alcohol, C12-13 Pareth-23, C12-13 Pareth-3, Hydrolyzed Vegetable Protein Pg-Propyl Silanetriol, Limonene, Arginine, 2-Oleamido-1,3-Octadecanediol, Poly (Linseed Oil), Benzophenone-4, Phenoxyethanol, Citronellol, Ci 14700/Red 4, Methylchloroisothiazolinone, Sorbic Acid, Haematococcus Pluvialis Extract, Magnesium Chloride, Methylisothiazolinone, Caprylic/Capric Triglyceride, Potassium Sorbate, CI 15510/Orange 4.
Conditioner Ingredients: Aqua/Water/Eau, Cetearyl Alcohol, Behentrimonium Chloride, Amodimethicone, Parfum/Fragrance, Isopropyl Alcohol, Phenoxyethanol, Benzoic Acid, Trideceth-6, Hexyl Cinnamal, Tocopherol, Olea Europaea Fruit Oil/Olive Fruit Oil, Camelina Sativa Seed Oil, Poly(Linseed Oil), Butylene Glycol, Linalool, Potassium Hydroxide, Dilauryl Thiodipropionate, Arginine, Cetrimonium Chloride, Helianthus Annuus Seed Extract/Sunflower Seed Extract, Hydrolyzed Vegetable Protein Pg-Propyl Silanetriol, Limonene, 2-Oleamido-1,3-Octadecanediol, Citric Acid, Benzophenone-4, Citronellol, Haematococcus Pluvialis Extract, Ci 14700 / Red 4, Caprylic/Capric Triglyceride, Potassium Sorbate, Ci 15510 / Orange 4.
This mask is a targeted nutritive treatment meticulously formulated to address the needs of distressed hair. Its enriching constituents work synergistically to provide comprehensive care, spanning from the roots to the ends of the hair strands. Particularly effective in revitalizing dry and damaged hair, its transformative effects become discernible with just the initial use.
Ingredients: Water, cetearyl alcohol, cetrimonium chloride, isopropyl alcohol, triticum vulgare(wheat) germ oil, panthenol, propylene glycol, amodimethicone, polyquaternium-11, chondrus, ciprus (carrageenan), tocopheryl acetate, linoleamidopropyl pg-dimonium chroide phosphate, trideceth-12, lecithin, sodium methylparaben, limonene, linalool, phenoxyethanol, potassium sorbate, ci 19140 (FD&C yellow no.5), CI 42053(FD&C green no.3), CI 16035 (FD&C Red no.40).
This is a potent hair treatment infused with ceramides, which is ideal for addressing dryness and damage.
Ingredients: Aqua, Cetyl Alcohol, Cetrimonium Chloride, Mineral Oil, Stearyl Alcohol, Glycerin, Fragrance, Dimethicone Copolyol, Cyclomethicone, Keratin, Diazolidinyl Urea, Iodopropynyl Butylcarbamate, Ceramide, Citric Acid.
This is a dynamic hair treatment enriched with ceramides, which is a targeted solution for dryness and damage, with ceramides playing a pivotal role in its restorative capabilities.
Ingredients: Aqua / Water / Ceramide 3, Caprylic/Caplic Triglyceride, Myristoyl/ Palmitoyl/ Oxostearamide/ Arachamide MEA, Sorbitan Stearate, Phytosterols, Capry Glycol, Stearic Acid, Xantan Gum, Cyclopentasiloxane, PEG/PPG-18/18 Dimethicone, Cethyl Alcohol, Cetearyl Alcohol, Behentrimonium chroride, Bentrimonium Methosulfate, Stearyl Alcohol, Dimethicone, Safflower Oil, Shea Butter, Amodimethicone, Cetrimonium Chloride, Trideceth-12, Panthenol, Macadamia Oil, Tocopheryl Acetate, Citric Acid, Tetrasodium EDTA, Sea Water Extracts, *Aloe vera Extract, *Calendula Extract , *Green Tea Extract, *Chamomile Extract , *Horsetail Extract , *Acai Extract, *Lavender Extract, *Panax Ginseng Extract, *Rosemary Extract , *Sage Extract , *Comfrey Extract , *Nettle Extract , *Quinoa Extract. (*USDA Certified Organic).
Infused with fortifying ceramides and proteins, this multipurpose spray offers a comprehensive approach to hair repair and revitalization. By addressing damaged strands, it not only enhances hair’s resilience but also minimizes the visibility of split ends, all while providing a protective shield against future breakage.
Ingredients: Aqua/Water/Eau, Polyacrylamide, Phenoxyethanol, Amodimethicone, C13-14, Isoparaffin, Isopropyl Myristate, Parfum/ Fragrance, Laureth-7, Xylose, Hydrolyzed Soy Protein, Trideceth-6, Hydrolyzed Vegetable Protein PG-Propyl Silanetriol, Arginine, Citric Acid, Cetyl Alcohol, Cetrimonium Chloride, Behentrimonium Methosulfate, Benzyl Benzoate, Quaternium-33, Limonene, Benzyl Alcohol, Linalool, 2-Oleamido-1,3-Octadecanediol.
For those with hair that has weathered storms or undergone countless changes, this mask stands as your trusted ally. Its luxuriously velvety texture delicately envelops your hair, orchestrating a revitalizing symphony for each strand. The formula’s masterpiece lies in the meticulous fusion of natural ceramides and their synthetic counterparts, seamlessly collaborating to fortify and moisturize, imparting a sense of renewal and resilience.
Ingredients: Aqua/Water, Cetearyl Alcohol, Paraffinum Liquidum/Mineral Oil, Orbignya Oleifera Seed Oil, Dipalmitoylethyl Hydroxyethylmonium Methosulfate, Parfum/Fragrance, Cetyl Esters, Cetrimonium Chloride, Caprylyl Glycol, Linalool, Citric Acid, 2-Oleamido-1,3-Octadecanediol, Citronellol, BHT, Glycine, Arginine, Proline, Tyrosine, Glutamic Acid, Geraniol, Serine, Hydroxypropyltrimonium Hydrolyzed Wheat Protein, Benzyl Alcohol, Safflower Glucoside, Isoeugenol, Glycerin, Trehalose, Tamarindus Indica Seed Polysaccharide, Myrothamnus Flabellifolia Leaf Extract.
This is an airy, reparative oil that imparts hydration, strength, and sleekness to strands, resulting in glossy, frizz-free hair.
Ingredients: Cyclopentasiloxane, Dimethiconol, Caprylyl Methicone, Phenyl Trimethicone, Argania Spinosa (Argan) Kernel Oil, Oryza Sativa (Rice) Bran Oil, Bambusa Vulgaris (Bamboo) Extract, Hydrolyzed Soy Protein, Moringa Oleifera Seed Oil, Glyceryl Linoleate, Tocopherol, Water, Glycerin, Fragrance, Polysilicone-15, Glyceryl Linolenate, Potassium Sorbate, Dimethicone Crosspolymer, Phenoxyethanol, Benzyl Salicylate, Citronellol, Geraniol, Hydroxycitronellal, Butylphenyl Methylpropional, Limonene, Linalool, Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde, Alpha-Isomethyl Ionone.
The Total Repair 5 Damage Erasing Balm is designed to combat five distinct indicators of damage in hair. Crafted with a selection of nurturing components, including almond oil and a substantial 17 percent repair concentrate with protein, this formula delivers comprehensive care. Its fragrance is an elegantly intricate composition, blending floral and creamy notes with a touch of invigorating green undertones. As a sumptuous treatment, this balm provides profound conditioning, fostering both nourishment and repair for the hair.
Ingredients: Aqua/Water/Eau, Cetearyl Alcohol, Behentrimonium Chloride, Amodimethicone, Candelilla Cera/Candelilla Wax/Cire De Candelilla, Cetyl Esters, Glycerin, Isopropyl Alcohol, Parfum/Fragrance, Phenoxyethanol, Trideceth-6, Hydroxypropyl Guar, Prunus Amygdalus Dulcis Oil/Sweet Almond Oil, Linalool, Cetrimonium Chloride, Benzyl Salicylate, Chlorhexidine Dihydrochloride, Benzyl Alcohol, Hydroxypropyltrimonium Hydrolyzed Wheat Protein, Limonene, Amyl Cinnamal, Coumarin, Citronellol, 2-Oleamido-1,3-Octadecanediol, Alpha-Isomethyl Ionone, Ci 19140/Yellow 5, Argilla/Magnesium Aluminum Silicate, Prunus Amygdalus Dulcis Fruit Extract/Sweet Almond Fruit Extract, Ci 15985/Yellow 6, Xanthan Gum, Citric Acid, Sorbic Acid, Fil Code D202830/1.
This remarkable treatment, enriched with sunflower seed oil and hydrolyzed silk, incorporates potent smoothening agents that specifically target areas requiring repair, while also offering protection against potential future damage.
Ingredients: Water (Aqua/Eau), Cetearyl Alcohol, Cetyl Esters, Behentrimonium Chloride, Glycerin, Amodimethicone, Fragrance (Parfum), Helianthus Annuus (Sunflower) Seed Oil, Hydrolyzed Silk, Phenoxyethanol, Trideceth-12, Cetrimonium Chloride, Disodium EDTA, Magnesium Nitrate, Sodium PCA, Methylchloroisothiazolinone, Magnesium Chloride, Methylisothiazolinone, Tocopherol, Benzyl Benzoate, Red 33 (CI 17200), Red 4 (CI 14700).
Ceramides, natural lipid molecules inherent in human skin and hair fibers, play a pivotal role in maintaining structural integrity.
Within the hair’s architecture, ceramides function as guardians, compacting cuticles while enhancing surface smoothness. Their involvement extends to influencing hair fiber tensile properties, underscoring their significance in hair mechanics.
The absence of ceramides precipitates a decline in hair integrity, leading to weakened fibers. The versatility of ceramides allows for their incorporation into various hair product formulations, yielding substantial restorative effects on natural texture, shine, and overall fiber quality.
Incorporating ceramides infuses strength into hair fibers, markedly reducing friction and thus facilitating easier combing and styling.
The inclusion of ceramides therefore not only safeguards the health of hair but also elevates its aesthetic and tactile attributes.