Methyl cellulose (or methylcellulose) is a compound derived from cellulose. It is sold under a variety of trade names and is used as a thickener and emulsifier in various food and cosmetic products, and also as a bulk-forming laxative. Like cellulose, it is non-digestible, non-toxic, and not an allergen. In addition to culinary uses, it is used in arts and crafts such as papier-mâché and is often the main ingredient of wallpaper paste.
Uses Methyl cellulose has a wide range of uses.
Medical
Constipation Methylcellulose is used to treat constipation and is classified as a bulk forming laxative. It works by increasing the amount of stool present which improves intestinal contractions. Effects generally occur within three days. It is taken orally with sufficient water. Side effects may include abdominal pain. It is available over the counter. It is sold under the brand name Citrucel among others.
Artificial tears and saliva The lubricating property of methylcellulose is of particular benefit in the treatment of dry eyes. Solutions containing methyl cellulose or similar cellulose derivatives are used as substitute for tears or saliva if the natural production of these fluids is disturbed.
Medication manufacturing Methyl cellulose is used in the manufacture of drug capsules; its edible and nontoxic properties provide a vegetarian alternative to the use of gelatin.
Consumer products
Thickener and emulsifier Methylcellulose is occasionally added to hair shampoos, tooth pastes and liquid soaps, to generate their characteristic thick consistency. This is also done for foods, for example ice cream or croquette. Methylcellulose also prevents the separation of emulsions because it is an emulsion stabilizer.
Food The E number of methylcellulose as food additive is E461. E464 is hydroxypropyl methylcellulose, which is more soluble in water. Methylcellulose, as a gel, has the unique property of setting when hot and melting when cold. In some meat analogues that are intended to replicate the texture of meat, methylcellulose is used as an ingredient, typically in concentrations less than 2%.
Lubricant Methyl cellulose may be used in personal lubrication.
Construction materials Methyl cellulose finds a major application as a performance additive in construction materials. It is added to mortar dry mixes to improve the mortar's properties such as workability, open and adjustment time, water retention, viscosity, adhesion to surfaces etc. Construction grade methyl cellulose is not to be identified with food and pharmaceutical grade methyl cellulose and hydroxypropyl methyl cellulose, as it may be cross-linked with glyoxal for easy dispersion in water. The construction materials can be cement-based or gypsum-based. Notable examples of dry mixture mortars which utilize methyl cellulose include tile adhesives, EIFS, insulating plasters, hand-trowelled and machine-sprayed plaster, stucco, self-leveling flooring, extruded cement panels, skim coats, joint & crack fillers, and tile grouts. Typical usage is about 0.2% – 0.5% of total dry powder weight for dry mixtures. Derivatives of methyl cellulose which improve performance characteristics include hydroxypropyl methyl cellulose (HPMC) and hydroxyethyl methyl cellulose (HEMC). These derivatives typically improve the characteristics such as water retention, vertical surface slip resistance, open time, etc.
Glue and binder Methyl cellulose can be employed as a mild glue which can be washed away with water. This may be used in the fixing of delicate pieces of art as well as in book conservation to loosen and clean off old glue from spines and bookboards. Methyl cellulose is the main ingredient in many wallpaper pastes. It is also used as a binder in pastel crayons and also as a binder in medications. Hydroxypropyl methylcellulose (HPMC) is an FDA-approved water-soluble adhesive, has been used in various wet-adhesion applications in construction products, paints, and drug delivery for 70 years. HPMC adheres strongly to all wet surfaces, regardless of hydrophobicity.
Paint Methyl cellulose is used as a rheological modifier in paint to prevent 'sagging'.
Paper and textile sizing Methyl cellulose is used as sizing in the production of papers and textiles as it protects the fibers from absorbing water or oil. When applied to several pieces of paper, methyl cellulose will bind the layers together, often to create a more durable or multicolored sheet. In addition, origami artists use it to coat their origami models, as the compound will stiffen and protect the paper against time.
Dust control Hydroxypropyl methyl cellulose (HPMC) and hydroxyethyl methyl cellulose (HEMC) are used as binders in dust control technologies. They mitigate fugitive dust released in arid and semi-arid areas as well as improve commercial face masks when used in the filtering material.
Cell culture Methyl cellulose is also used in cell culture to study viral replication. It is dissolved in the same nutrient-containing medium in which cells are normally grown. A single layer of cells is grown on a flat surface, then infected with a virus for a short time. The strength of the viral sample used will determine how many cells get infected during this time. The thick methyl cellulose medium is then added on top of the cells in place of normal liquid medium. As the viruses replicate in the infected cells, they are able to spread between cells whose membranes touch each other, but are trapped when they enter the methyl cellulose. Only cells closely neighboring an infected cell will become infected and die. This leaves small regions of dead cells called plaques in a larger background of living uninfected cells. The number of plaques formed is determined by the strength of the original sample.
Bacterial and protozoal motility inhibitor Aqueous methyl cellulose solutions have been used to slow bacterial and protozoal cell motility for closer inspection. Changing the amount of methyl cellulose in solution permits the adjustment of the solution's viscosity.
Stem cell differentiation Methyl cellulose is used in the most common approaches to quantify multiple or single lineage-committed hematopoietic progenitors, called colony-forming cells (CFCs) or colony-forming units (CFUs), in combination with culture supplements that promote their proliferation and differentiation, and allow the clonal progeny of a single progenitor cell to stay together and thus form a colony of more mature cells.
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