LEATHER
Leather
is one of the toughest and most hardwearing natural substances known.
It is made from the skin of animals, prepared and treated in such a
manner that it does not decompose, and becomes supple (flexible) and
resilient (resuming it’s original shape after compression). Large
skins are called ‘Hide’ and are derived from oxen and horses.
Smaller skins are derived from goat, sheep, etc.
MAKING
- The skin is first washed with water to soften
- Then it is treated with lime to remove hair and loose skin
- They are often then treated to remove lime and then tanned
- Tanning process is carried out by the means of tannin from the bark of oak and other substances. It is very slow and takes several weeks
- After tanning leather is finished and dressed according to the kind of leather required and the purpose it is required for.
METHODS OF DRESSING
- Currying – In this leather is smoothened and pared down on the flesh side, or is split if thick, into several layers. It is rendered soft and pliable and made waterproof. Waterproofing is done by allowing a mixture of tallow (animal fat) and cod liver oil (large sealfish) to penetrate the leather gradually.
- Tawing – This is the treatment of skin by mineral salts and is employed for glove leather and soft leather for boots and shoes.
- Shamoying – It is the process of making the leather very soft and pliable by soaking it with oil, and was originally used from deer and chamois skin. Most leather of this nature is obtained from split sheep and also known as wash leather.
MOROCCO LEATHER
Originally
derived from goatskin, dyed and richly grained, this name is now
applied to any leather (chiefly split calf and sheep skin) finished
to resemble Morocco leather.
RUSSIAN LEATHER
This
similarly is any leather with a smooth finish and treated with
aromatic oils which gives it it’s characteristic odor.
SYNTHETIC LEATHER
These
are very tough and durable. Imitation leather was originally made by
spreading a mixture of various substances, such as linseed oil, dyes
and pigments on a canvas or other backing and finished to resemble
leather.
CARE
AND CLEANING
- Leather upholstered furniture should be kept free from dust especially in folds or round buttons.
- Good furniture creams help to keep it in good condition.
- Oil and waxes make it supple and prevents cracking.
- Dirty leather maybe wiped clean with damp cloth and liquid wax.
Polishes
– This consists principally of a waxy substance or an oil,
turpentine, a colouring matter and a preservative. For black polishes
carbon is used in finely divided condition. For brown polish yellow
ochre (earth used as yellow, brown and red pigments) and other
pigments are used.
PATENT LEATHER
This
requires grease of some kind to prevent cracking and hardening while
not in use. Rub with vaselene or olive oil. Before using, all traces
should be removed by rubbing with a soft cloth. Polish with
commercial cream sold for this purpose.
SUEDE
Remove
mud by brushing well with soft rubber brush. Clean with either a
liquid suede cleaner or a cleaning block, which is rubbed on the
leather to remove dirt and restore the nap (raised pile). If suede is
shiny use old fine emery paper.
WHITE AND PALE COLOURED LEATHER
Sponge
off marks with a damp soapy cloth. Apply cream, wipe with a clean
damp cloth and polish with a soft duster.
حشرة من رتبة مستقيمة الأجنحة صغير له ست أرجل، أجنحة شفافة بنية اللون، جسمه مفلطح بيضي يضرب لونه للسمرة، و له قرنا الاستشعار طويلان والعينان كبيرتان وللصرصور رائحة كريهة من إفراز غدي وهو يأكل ما يصادفه و يتكاثر عن طريق البيض الذي تبيضه أنثى الصرصور حيث تفرز الأنثى مادة عطرة تعلن فيها استعدادها للجماع يلتقطها الذكر بقرونه الاستشعارية فينجذب إليها الذكر ويمكن أن تبيض أنثى الصرصور لمدى الحياة بمجرد التقائها بالذكر لمرة واحدة. يوجد في العالم 3500 نوع من الصراصير وقد أثبتت أبحاث علمية إن الصراصير توجد على سطح الأرض منذ خمسين مليون سنة أي سابقة وجودنا على هذه الكوكب بست وأربعين مليون سنة عن وجود الإنسان على كوكب الأرض والذي يقدر بأربعة ملايين سنة وهذا يعني أنها من أوائل المخلوقات التي وجدت على سطح الأرض ويصنف الصُّرْصُور ضمن الحشرات القارضة حيث يستعمل فكيه الأماميين الذي يسميان الفكوك الطاحنه لتمزيق و لقطع ومضغ الطعام كما يوجد زوج من الفكوك أقلّ قوّة من الفكوك الأمامية يُسمّى الفكوك الخلفيّة وتُستعمل في التعامل مع الطعام ودفعه إلى أسفل الحنجرة. وله شفتان؛ الشفة العليا، وهي غطاء يتدلى إلى أسفل فوق أجزاء الفم مغطيًا الفم من الناحية الأمامية. أمّا الشفة السفلى فهي تغطي الفم من الخلف .
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