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2.3-2 Knowledge of dirt (what dirt?)



House dirt is foreign substances that attach to and contaminate floors, walls, pillars, ceilings, partitions, and furniture. To distinguish among many types of dirt, you need to examine why it got dirty (source), what kind of dirt it is (type), how it is attached (condition of attachment), and when it got dirty (chronological change).

★What dirt? Steps to analyze dirt
(1)Examine why it got dirty  (2) Examine what kind of dirt it is  (3) Examine how it is attached  (3) Examine when it got dirty and how it changed over time


(1) Why did it get dirty? Examine the source
The first thing to check when you want to know about dirt is the source of contamination. Ignorance leads to employment of wrong technique, resulting in Muda (waste of labor) and sometimes damage to architectural materials. Examining dirt enables us not only to guess the mechanism of contamination and chief component of dirt, but also to prevent the same kind of contamination from troubling us again.
They are ways for foreign substance to get attached to architectures; "natural source" and "man-made source."

 1) Natural source
Even an uninhabited house gets dirty after a period of time. The sources are...
1. Particles floating in the air such as dust, pollen and carbon, get carried in by air current or enter through a small gap and get attached to architectural materials.
2. Substances mixed in rainwater get dried up and adhere.
3. Activities of animals such as excretion.
4. Outbreak of mold and hygiene pests.
5. Chemical substances in the air or acid rain cause chemical reactions.
6. Others


2) Man-made source
Different substances attach to houses as people use them. This source accounts for the contamination more than natural sources do. The sources are...
1. Mad and dust on shoe soles spread by walking.
2. Grime, secretions, excretions, fallen hair, etc.
3. Food and drink, fumes from cooking oils, smoke and ash of cigarette, etc.
4. Strips(?) produced by moving things
5. Dust and strips(?) from cloth
6. Others



(2) What kind of dirt? Examine types.
Though there are various types of dirt, general categories include water-soluble substances (dirt that blends with water), oil-soluble substances (dirt that repels water), and other contaminating substances, each of which requiring different types of detergents. In reality, however, dirt consists of multiple substances in a mixed form. A Practical solution is to discern the chief component from surrounding conditions, smell , touch, and investigate whether it blends with or repels water.

1) Basic investigation of dirt
1. Analyze attached dirt from the source of contamination and surrounding conditions.
2. See if it blends with or repels water.
3. Analyze from smell and touch.


※ Since dirt consists of multiple substances in a mixed form, the more you investigate, the more you will find. So-called house dust is mixture of different kind of dust generated inside a house except for those that enter from outside such as pollen and soil dust. As most types of house dust are tiny particles of fiber of cloth and papers, we call it "lint." Other substances include dandruff, grime, debris of food, pets' hair, mold, ticks, etc. Toxic matters in the air add to this diversity. Therefore, it is advisable to undertake a basic investigation to distinguish the chief component when you try to analyze the type of the dirt that you want to clean.



(3) How is it attached? Examine the condition of attachment
The same type of dirt may require different technique if its condition of attachment is different. Moreover, the types of dirt and the types of architectural materials make a difference in the condition of attachment. Some dirt is just sitting on the surface of the material while another permeates the material with water-absorbability. When you try to remove dirt, you need to know the condition of attachment and the mechanism that is functioning there as well as the type and nature of dirt. Not only the types of dirt but also the disposition of architectural materials and the chronological change after the attachment influence the condition of attachment.
As in the above, there are various conditions of attachment, ranging from a simple one to a complicated one, and mechanism working there is no less diverse. I will illustrate the typical conditions of attachment below.
Other phenomena such as getting rusty, getting dull, getting scarred, getting burned, coming off, getting discolored or faded are considered to be dirt or the condition of attachment of dirt.


(4) When did it get dirty? Examine chronological change
Some dirt transforms over time through processes such as oxidation and solidification. For instance, steel gets rusty (rust is oxidized steel) by oxidation. Tannin contained in coffee and green tea makes stain that becomes harder and harder to remove. Hence, it is important to deal with dirt as soon as possible. It is also notable that you need to adjust your cleaning method according to time elapsed.

1) Examples of dirt and chronological change


① Dirt such as dust builds up on old air conditioner's filters and disable their filtering function. This type of dust contains more moisture and fat content than regular dust and is harder to remove because it has been solidified by air pressure over a long time. Physical force such as brushes used together with a vacuum is an optimal solution.

② Smoking over a long period of time browns the cover of an air conditioner all over. It looks dirtier than wallpaper around it because greasy dirt sticks to conditioner's plastic materials and also because it is staticky.

③ Dirt on gas stoves. Liquid spilled during cooking has got solidified with time and now it is stuck really hard. It would have been much easier if you took action immediately after spilling happened.

④ Mold damages wallpaper. After the outbreak it proliferates and widens the range of contamination. If left untouched, mold could discolors and damages wallpaper and it is not good in terms of sanitary too