# Cleaner Processes for Making Laundry Soap from Vegetable Oils and an Essential Oil
## 1 Introduction
The literature presents the composition of Australian Tea Tree essential oil according to gas chromatographic analysis: 93.6% terpene hydrocarbons (as Terpinen-4-ol (40.1%), \(\gamma\)-Terpinene (23%), \(\alpha\)-Terpinene (10.4%), 1,8-Cineole (5.1%), Terpinolene (3.1%), \(\rho\)-Cymene (2.9%), \(\alpha\)-Pinene (2.6%), \(\alpha\)-Terpineol (2.4%), Aromadendrene (1.5%), \(\delta\)-Cadinene (1.3%), Limonene (1%), Sabinene (0.2%)) and 0.3% related alcohols (Globul (0.2%), and Viridi-florol (0.1%)) [57; 58]. The main chemical constituents of Tea Tree essential oil obtained by steam distillation from the fresh leaves and twigs of _Melaleuca alternifolia_ plants grown in South Africa are 1-terpinen-4-ol (at least 30%), 1,6-cineole (less than 15%), pinene, terpinenes, carmine, sesquiterpenes, and sesquiterpene alcohol. _The essential oil of Thyme_ (_Thymus vulgaris_ L.) contains five classes of compounds: monoterpene hydrocarbons, oxygenated monoterpene, sesquiterpene hydrocarbons, oxygenated sesquiterpenes and others. Its main constituents are alpha-thujone, alpha-pinene, camphene, beta-pinene, para cymene, alpha terpinene, linalool, borneol, beta-caryophyllene, thymol, and carvacrol. The predominant compound of this essential oil composition is thymol (51.34%), while the amount of all other components of the oil (as \(\gamma\)-terpinene, p-cymene, carvacrol, and linalool) is found to be lower than 19% [59; 60]. Thymol, being predominant, determines the greatest antimicrobial effect and the other components confer both a synergistic effect and anti-inflammatory properties [61]. During saponification, temperature can affect the properties of the essential oil or raw material (fats/oils), which will be reflected in the final quality of the soap [39; 62], as follows:  
1. In the case of cold saponification, very-good-quality soaps are obtained, with a smooth surface and a well-defined geometric shape, which preserve the nutrients in the raw material, retain the additives better, as well as the glycerin. 2. In the case of hot saponification, good-quality soaps are obtained but are harder, slightly shiny, with a less fine appearance and a rougher texture because they contain fewer nutrients and glycerin due to its thermal degradation during processing. The efficiency of saponification can be appreciated according to the speed/production time or according to the energy consumption. From these points of view, cold saponification requires a longer production time (due to the maturation time of at least 4 weeks) but requires minimal energy consumption. Hot saponification generates soaps that can be used 1-2 days after production, but the energy consumption required to obtain these soaps is high. In both saponification processes (hot/cold), glycerin is also a result of the reaction by-product, which, not being removed, gives laundry soap the ability to improve the feel of washed laundry (as a fabric softener) and reduce electrostatic charge in textiles. The novelty of this article lies in the design of three natural laundry soaps, through cleaner saponification processes, obtaining exceptional washing and antimicrobial capacities. The cold/hot saponification processes based on two vegetable oils (olive and coconut) and an essential oil (Neem, Tea Tree and Thyme), considered safe by GRAS (Generally Recognized as Safe), generate soaps that do not cause any irritation or allergies and do not pollute wastewater and implicitly the environment. The influence of the essential oil on the effects created on textile materials, after washing with these soaps, is analyzed. The characteristics of these laundry soaps (pH, foaming, cleaning capacity, color) are superior to those of the commercial soaps used for comparison. This is the first time that the washing/cleaning capacity of soaps is quantitatively assessed by measuring the L*, a*, b* values on a high-precision Data Color spectrophotometer.