Medical Hydrology and Balneology: Environmental Aspects

Development and characterization of formulations
containing pumice from
São Miguel’s Island – Azores Archipelago
Amaral H (1) , Estanqueiro M (1) , Santos D (1) , Silva JBF (2) ,
Gomes CSF (2) , Sousa-Lobo JM (1)
(1) Department of Drug Sciences, Laboratory of Pharmaceutical Technology, Faculty of
Pharmacy, University of Porto, Portugal
(2) GeoBioTec, University of Aveiro, Aveiro, Portugal
hamaral.ffup@gmail.com
Introduction and Objectives
Pumice is a volcanic rock formed during explosive volcanic eruptions of acidic
and highly viscous magma; it is an extremely vesicular (vesicles are bubble-shaped
openings formed by the expansion of entrapped gases), frothy, natural glass having
a high (60-75%) silica content and very low density that in some cases float on
water; it consists of fragile acicular glass and minerals (in particular, feldspars).
Pumice stone has been used for centuries to remove rough and hardened skin, and it
is particularly effective when used to remove hard and rough skin on the feet, in
order to leave the feet feeling silky, smooth and velvety soft [1,2].
In this study, different particle size fractions of pumice sampled in several geologic
occurrences in São Miguel’s Island, the Azores Archipelago, were used in the
preparation of cosmetic formulations.
Materials and Methods
PFC 0.5% (w/w) gels were prepared incorporating pumice (5%, w/w) having the
following particle sizes: 250-500 µm (EP 250), 125-250 µm (EP 125) and < 63 µm
(EP 63). Soaps obtained by saponification of stearic acid with sodium hydroxide
(38%, w/v) were also prepared incorporating pumice having particle sizes within
the range 125-250 µm (SP 125). In stability tests, usually conducted at constant
temperature, the samples are periodically checked for changes in important features
[3]. In this work, texture (firmness and adhesiveness) and rheological studies, were
carried out 48 hours, 15 and 30 days after samples preparation. These formulations
were maintained at 20ºC throughout the test period. The evaluation of pH of gels
and soaps were also evaluated. Texture analysis is used to determine mechanical
characteristics of cosmetics since they must exhibit acceptable mechanical characteristics
e.g. ease of application and low firmness. Firmness is related to the ease of
application onto a substrate, whereas adhesiveness, a property related with
bioadhesion, describes the relative adhesive properties of a formulation [3]. Gels
Balnea
2012, núm. 6, 255-256
255
ISBN: 978-84-669-1887-0
978-84-669-3482-4