RESINS

RESINS

Resins are substances which develop in some

plant species as a result of the partial or plant

Complete oxidation of essential oils. Some

resins are sticky, viscous liquids, while others

are hard, brittle solids. Resins colour could

range from colourless to brown. Resins are

referred to as sap or exudates, both of which

include numerous substances from plants. It

 

can come from any part of a tree.

 

Resins are mostly insoluble in water and theyy

 

ultimately harden when exposed to aiT

 

Resins have some characteTistics that make

them important to industry. Their ability to

 

harden gradually helps in the making of

 

Commercial varnishes. Italso lowers the

 

Anothe property of resinsthat is

 

cmount of water lost from the plant tisstues.of to industrials importance is their ability

 

dissolve in alkalis to form soap. Resins arealso used in medicine: for sizing papers as a

 

stiffening material for mats: in the preparation

 

of sealing wax. incense and perfumes: and for

many other purp0ses as well.

Resin helps to prevent decay, which is due to

their high antiseptic qualittes

Resinous substances have beerm utilized for

waterprool coatings, and also for decorative

Coatings.

Classification of resins

 

Resins can be classified based on the

chemical composition

 

Hard resin

Oleo resin

Gum resin

HARD RESINs

these are resins that contain little or no

essential oil.

brittle substances with no particular odor or

taste. They are readily fuslble and burm in air

with a smoky lame. They are nonvolatile and

are poor conductors of electricity.

Ehey become negatively charged with frietion

They are used in varnishes, due to their low

oil content and the ease at which they dissolve

in alcohol. Hard resins are also used in

paints, inks.

fireworks and other products.

 

They are solid, transparent

 

plastics, sizing adhesives,

 

Some examples of hard resins

 

AMBER

This is plant resin obtained from Pinus

succinifer of the family Pinaceae.

Amber is very hard and brittle and occurs in

several forms. Some of these forms are

transparent while-others are almost opaque.

The color varies from yellow to brown and

even black. It also gives off a characteristic

aromatic odor. 1t is used in the production of

jewelry, and ornamentals

Amber is used for the mouthpieces of pipes

and cigarette and cigar holders. The darker

grades yield a valuable varnish. but this is tóo

costly for general use.

Amber is also used to increase the elasticity of

ravon fbers.

Damars: BalanOcarpus SPP

It belongs to the family Dipterocarpaceae

1s insoluble in chloral hydrate, but complete

soluble in alcohol and turpentine. Jt is used t

the production of vamishes

Lacquer

These are natural varnishes that exude fro

Various trees in Asia, and are uscd mainly

ornamental purposes.

The main source is the lacquer tree, Rha

Derniciflua native to China but cultivated

dapan 1he trees are systematically tappede

The exudate is a milky liquid, which darke

and thickens rapidly on exposure to

When applied as a varnish. the thin rapidly hardens in a moist atmosphere, In

part due to oxidation. Lacquer imparts a

remarkable protection as it is unchanged by

acids, alkalis, and alcohol or heat up to 71

deg. Celsius. Pigments may be mixed with the

lacquer before drying.

 

Copal: Trachylobuim spp

Copals

Trachylobuim sp of the family Fabaceae.

Copals are resins of recent, semi fossil and

fossil origin that are found in many tropical

and subtropical areas of the world. They have

insignificant quantities of oil and they yield a

hard elastic varmish, which has been widely

used for outdoor work. The stems, twigs and

even the fruits exude a large amount of resin.

which trickles to the ground. It 1s used in

varnishes.

Shellac

 

1s a brittle or flaky secretion of the lac 1nseet

Kerria lacca found in forest of Assam and

Thailand. True shellac is not a direct plant

product. It is made from stick-lac. a resinous

Substance secreted on the twigs of 1nany Lrees

by an insect, K lacca The lac insect derives

its food from the sap of the trees and secretes

the resin as a kind of cocoon for its own

protection and that of its offspring

 

 

 

 

Updated: February 10, 2020 — 8:09 pm

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