What is CMC Gum?

The term CMC is generic and refers to organic sodium carboxymethylcellulose. Gums are used in ceramics to harden unfired ceramic glazes. This makes for safer handling of ware, better adherence to the body, slower drying (thus better brushability). CMC gum also reduces drying shrinkage and enables multi-layering without flaking or cracking. Highly fritted glazes (lacking clay content) used in factory settings benefit greatly from the addition of gum. Single layer cover glazes that have natural hardening properties (i.e. from 15% or more clay) do not need gum. Gum is an important addition to stain mixes that are applied over-glaze by stamping or painting.

In dipping glazes, gum can act as a suspending agent (but this is seen as a side effect, there are much better ways to suspend slurries). CMC gum makes slurries stickier, more difficult to clean off tools and containers. CMC-containing slurries do not respond to gelling (via epsom salts or calcium chloride) so the main way to control the thickness is by adjusting specific gravity. This makes it difficult to tune the rheology of dipping glazes that need CMC gum (to enable them to handle over layering). The slower drying makes it difficult to achieve an adequate glaze thickness and prevent drip marks during dipping.

CMC gum in the water is preventing this powder from slaking:

Normally the powder would slake and settle to the bottom immediately. Mixing this requires a powerful mixer and plenty of time to remove all the lumps. The proportion of gum in the water amounts to 1.5% the total weight of the powder in the glaze.

Fuction & Application:

CMC Food Grade:

CMC is widely used in food industry, it play the roles of taste improvement, thickening and stabilization when used in various kinds of dairy drinks and seasonings. As an additive of molding, taste improvement, anti-fragmentation, water retaining and tenacity strengthening, CMC is also used in ice cream, bread, cake, biscuit, instant noodle and fast paste foods.

The recommended addition is 0.3-1.0%.

CMC Toothpaste Grade:

CMC has an efficiency of adhesion and molding when used in toothpaste, and stabilizes the quality of toothpaste owing to good compatibleness.

The recommended addition is 0.5-1.5%.

CMC and PAC for Oil Drilling:

CMC and PAC can reduce water loss, and increase viscosity in drilling fluid, cementing fluid and fracturing fluid. They play the roles of protecting the wall of well, taking drilling trifles, protecting drilling bit, preventing mud loss and increasing drilling rate.

Usage: add to mud directly or glue solution preparation.
Addition:

0.1-0.3% in fresh water mud;

0.5-0.8% in salt water mud.

CMC Ceramic Grade

CMC is used for ceramic embryo, glazing pulp and colored glaze in ceramic industry.

Addition:

0.03%-0.2% used in ceramic embryo;

0.05-0.2% used in glazing pulp;

1.4-4.0% used in colored glaze.

CMC Paper Grade

In making paper, CMC is used in making pulp so as to improve the retention rate and increase humidity and strength; when used in surface sizing, CMC can improve internal adhesion, decrease printing dust and enhance printing quality as molding reagent. In paper coating, CMC also helps the dispersion and fluidity of paint, improves appearance of paper and smoothness, upgrades optical performance and printing adaptability.

Addition: 0.3-1.5%.

CMC for Other Industries

As coagulant, water retaining, thickener and binder, CMC is also used in paint, carpet gum, mosquito coil incense, tobacco, electric welding, textile, battery, printing and others.