Classification, detection and evaluation of Stone cleaner
Nearly two decades, stone has become one of the most fashionable architectural decoration materials, and its natural and simple appearance is incomparable to other decorative materials.But, the stone 'fault' that had not expected before also shows more and more now.For example, the stone rust spot that often sees, organic color spot, water mark and water spot, salt spot and white hua, surface loses light and oily spot to wait.These blemish destroyed the adornment effect of stone material original, and clear them to have quite difficulty, because they already went deep in the micropore of stone material, not be ordinary surface is scrubbed can clear, and knock off heavy outfit cost is considerable.Therefore, the corresponding cleaning and prevention technology came into being.The special cleaning medicaments of stone material has become the indispensable branch field in stone material industry, showing the economic prospect that can concept.At present, the development, production and use of China's stone cleaning agent is still in its infancy. It is of great significance for the development of China's stone cleaning industry to standardize the testing and evaluation methods of stone cleaning agent as soon as possible.This article is only an exploration for the reference of people inside and outside the industry.
1. Classification of stone cleaning agent
Stone cleaning agent can be divided into liquid type, aerosol type, powder type, etc.
According to the properties of the solvent can be divided into: water, solvent, emulsion, gel, etc.
According to the cleaning agent can be divided into: acid type, neutral type, alkaline type;
Can also be divided into cleaning objects: remove all kinds of dirt (inorganic dirt, such as rust, ink, white, salt spots, water spots, etc.;Organic dirt, such as oil spots, tea stains, biological pigments, etc.) special cleaning agent.
Because the reason that stone material surface dirt forms is very different, the action principle of corresponding cleaner and use method are different inevitably also.Therefore, stone cleaning agent must be marked categories, especially cleaning objects and conditions, as well as a detailed method of use.
Obviously, stone cleaning agent unlike protective agent, it is difficult and not necessary to unify all technical requirements.Different cleaning agents can be based on their own characteristics of the basic performance and decontamination ability of the test.Basic performance measurement is to ensure the stone, environment, human harmless, decontamination ability measurement is to determine the cleaning effect of cleaning agent.
2. Basic performance
The basic properties of stone cleaner include physical and chemical properties.Main should:
(1) appearance: cleaning agent liquid products (except slurry products) shall not be layered, suspended or precipitated;Aerosol products should not show significant phase separation;The powder product should not be caked.This is the most basic way to determine whether a product has gone bad.
(2) smell: cleaning agent should not be similar to benzene, kerosene, fish fishy, spicy and other pungent smell or odor, and should not make cleaned stone left obvious smell.This is the most basic way to determine whether a product is contaminated.
(3) removability: when cleaning with water or other materials, cleaning agents and products should be able to be completely removed.This is the most basic way to determine whether a product will remain
(4) flash point: the flash point must be measured for solvent products, which can be measured in accordance with astm-d39.This is the most basic way to determine whether a product is flammable or explosive.
(5) pH measurement: at room temperature, the pH value of the cleaning agent stock and the pH value (accurate to 0.1 pH) at the applied concentration was measured with a pH meter and marked.
(6) stability: stability mainly depends on the stability of the cleaning agent at high or low temperature: pour the liquid cleaning agent into a clean 60ml glass reagent bottle, put it in a 40±1℃ oven or a 3 ~ 10~ (2 refrigerator, take it out after 24h, put it in the room to restore to room temperature, check its appearance and smell, compared with the determination should be basically unchanged.
(7) toxicity: that is, safety.Cleaning agent raw materials should not contain toxic raw materials, such as hydrofluoric acid.The harm of cleaning agent to human body and the environment is a very important problem. Recently, a city in zhejiang province happened the incident of poisoning death after the outer wall cleaning agent was poured on the human body.Toxicity, possible irritation and damage to the skin, mucous membranes, and respiratory system, as well as the resulting environmental hazard, may be determined by the department of health's environmental disinfectant test (or by the recently published archives of environmental health of the American medical association).At present, the detection of related cleaning agent toxicity is still a weak link in China, and few detection methods can be referred to.However, the harm and negative effect of human body, biology and environment will attract more and more attention from the society. It is necessary to include toxicity test and evaluation method of cleaning agent in the specification of stone cleaning agent prospectively.
3. Test method of detergent decontamination ability
3.1 preparation of stone samples
The actual stain is very different, in order to facilitate in the laboratory to assess the detergent deconfouling effect, should first unify the stone stain sample laboratory preparation process.Common stone stains mainly have: rust spot, white China (salt spot).Water spots.Organic stains (tea, coffee, straw rope yellow, biological excretion or decay, etc.).Grease spots (including lipids and waxes).Divided into mineral, plant, animal).Cement spot, glue or adhesive, etc.Old dust and dirt.Chemical dirt such as ink, microbial stains, etc.In order to ensure the consistency of the standards, the method of preparing smear samples in the laboratory should be representative, and the closer to the reality, the better.We already have a method for making such stains, which I will not describe here for the sake of space.
3.2 cleaning steps of samples
Because the dirt of stone material and the kind that clean agent are various, use method also is each different, so unified clean step is difficult, the method that can according to the use instruction book place that can produce a manufacturer to introduce only undertakes generally.In order to evaluate decontamination effect more scientifically, it is required to set;
(1) blank sample: that is, the same stone sample without stains and without cleaning, as a reference for cleaning effect, cleaning influencing factors and residual comparison;
(2) blank cleaning samples: that is, the same stone samples without stains but cleaned in the same way, to compare the impact of cleaning on the appearance and surface morphology of stone;
(3) reference sample: that is, the stone sample that has stains and is cleaned only with similar solvent of cleaning agent to ensure the credibility of artificial stains.In addition, at least three parallel samples are required for the cleaning and testing of stone stains to reduce accidental errors.
3.3 inspection and evaluation of cleaning effect
The inspection and evaluation of stone cleaning effect mainly includes two aspects, one is the improvement of appearance, the other is the improvement of surface properties (especially the cleaning of stone cultural relics must be examined and evaluated).It should be pointed out that numerical value should be used as far as possible to reduce the influence of human factors.
3.3.1 changes in stone appearance, the detection methods are as follows:
Visually and visually judge the difference between the appearance of blank samples before and after cleaning;
Gloss meter, measuring the change rate of gloss of blank samples before and after stain cleaning (△Gs);
Three primary chromatimeters, measuring the chromaticity change rate (AE) of blank samples before and after stain cleaning;
A microscope.Microbe stains can be counted by microscope.Change rate of microbial sojourn before and after cleaning (△N) was measured.
The change of appearance of stone after cleaning can judge the change level according to the vision, glossiness meter, three primary chromaticity meter, microscope and so on.Here, naked eye vision may vary from person to person, the AGs, delta E, AN numerical size of the comparison is relatively easy to promote.
3.3.2 changes in surface characteristics of stone materials, the detection methods are as follows:
Water absorption coefficient, the change of water absorption coefficient between blank samples and after cleaning before and after cleaning was measured./ h);
Water vapor diffusion resistance, wet cup detection before and after cleaning stains, blank samples and after cleaning water vapor diffusion resistance difference delta.
The evaluation method for the change of surface properties of stone after cleaning can be based on the changes in the water absorption coefficient and water vapor diffusion resistance, AW and delta values are compared to evaluate (generally blank samples and cleaned delta w and delta value after the smaller the better).
3.3.3 evaluation and classification of stone cleaning effect
According to the appearance of the stone before and after cleaning and the determination of surface properties of the grading, generally can be divided into: special effects, obvious effect, effective and ineffective.The numerical results of the above instruments can be used not only to determine the effectiveness of cleaning agents, but also to determine the specific requirements of different levels of cleaning agents.
4. Influence of cleaning on stone materials and residue of cleaning agent
Cleaning for stone is a double-edged sword, it can eliminate stains, may also harm stone.In order to let people understand this kind of harm, especially to understand the long-term harm of cleaning agent to stone cultural relic, in the specification of stone cleaning agent must stipulate the detection and evaluation of this aspect.From the existing related specifications and standards, can refer to the test and evaluation methods are still very few, so that the residue impact problem has become a difficult point in the development of stone cleaner specifications.
4.1 test the influence of cleaning on stone materials
The influence of cleaning on the surface morphology of stone can be detected by the following methods:
Stereoscopic microscope: before and after stain cleaning, the change of morphology of blank sample and stone surface after cleaning was observed under stereoscopic microscope (digital value AZ could be obtained by adding camera and computer software);Surface roughness measuring instrument: the surface roughness measuring instrument is used to observe the roughness change of blank sample and sample surface after cleaning before and after cleaning (△Ra, △Rz);
Glossometer measures the change rate of glossiness of blank samples before and after stain cleaning (△Gs).
The destructive size of the stone surface can be measured before and after the use of cleaning agents according to the stone surface of △z, △Ra, ARz, △Gs values to compare and evaluate, (before and after the general cleaning AZ, ARa, ARz, AGs the smaller the better).Ratings can be divided into: no impact, small impact, impact and serious impact.The numerical results of the above instruments can also be used to specify the requirements of different grades of cleaning agents.
4.2 detection of residues and residues after cleaning
After cleaning, the chemical substance that remains on stone material and its residual quantity can use instrument analysis method to detect.Many instruments, such as energy spectrometers, atomic absorption spectrometers, can directly measure the sample of empty white stone and stone after cleaning.But in most cases, especially some simple chemical analysis methods often need to be cleaned from the stone samples of the chemical residues extracted.At present, the most convenient extraction method is to use the dip method or the sorption method, so that the residue transferred to the solvent, and then for analysis.The analysis after this kind of transfer has certain difficulty in quantity, but as long as the proper choice of reference matter, still can complete a lot of stone residue analysis, such as the total soluble matter, acid, salt, surfactant and other matters determination.Stone cleaning agent specifications should specify some of the greater harm of residue detection methods and permitted maximum residue.
4.3 assessment of the long-term impact of residues
At present, the negative effect of chemical substances remaining on stone materials, as well as the long-term effect of residues, can only be evaluated qualitatively.In the laboratory, part of the problem can be seen in a short period of time through the strengthening test, especially for some easily corroded stone.Can be used to strengthen the test such as: cleaning agent soak experiment, that is, in the specified time with cleaning agent soak some kinds of stone, in order to observe the negative impact on stone and so on.
All in all, this paper puts forward some testing and evaluation methods of stone cleaning agent, and hopes to discuss with people inside and outside the industry to make the development of China's stone cleaning industry more standardized and prosperous.