JP7828631B2 - Methods for preserving plants, animals, or excavated cultural artifacts - Google Patents

Description

This invention relates to a method for long-term preservation of plants, animals, and excavated cultural artifacts in their pre-excavation state, and more particularly to an improvement of a method for preserving plants, animals, or excavated cultural artifacts (hereinafter referred to as "artifacts, etc.") using higher alcohols.

Generally speaking, artifacts and other relics are part of humanity's cultural heritage, and their preservation is extremely important for understanding human lifestyles and environmental changes. Therefore, when preserving artifacts and other relics, it is desirable that they be treated in a way that preserves them permanently in the same condition they were in.

Incidentally, artifacts, especially those unearthed from moats surrounding archaeological sites, are often buried in clay or mud layers and therefore contain a supersaturated amount of water. As a result, after excavation, artifacts, particularly wooden ones, undergo decomposition and leaching of their main component, cellulose. Even if they initially retain their appearance due to moisture, as they dry, they undergo severe shrinkage, sometimes deforming to the point where they are unrecognizable. Similarly, plants and animals can shrink as they dry, deforming to the point where they are unrecognizable.

Therefore, conventionally, as a measure to preserve the original form of artifacts and other objects (hereinafter referred to as "objects"), methods have been employed such as impregnating the object with a water-soluble resin such as heated and melted polyethylene glycol (polyethylene glycol impregnation method), impregnating it with a mixture of tertiary butyl alcohol and polyethylene glycol in a certain ratio and then vacuum freeze-drying it (vacuum freeze-drying method), or impregnating it with a solution of higher alcohols.

However, in the polyethylene glycol impregnation method, there are concerns that if polyethylene glycol is used near its dissolution temperature, it will undergo air oxidation over time, causing the polyethylene glycol to change into a low molecular weight form. Furthermore, because polyethylene glycol is water-soluble and absorbs moisture from the air, it has the drawback of being prone to deformation and cracking of the treated object (hereinafter referred to as "treated object"). This necessitates the establishment of appropriate storage facilities and environments to improve preservation, and the impregnation process itself is lengthy.

On the other hand, vacuum freeze-drying also presents similar problems regarding shelf life because polyethylene glycol makes up about 50-60% of the material. Furthermore, there is a tendency for the rate of shape change to increase as the size of the material being preserved increases.

Therefore, a preservation method using higher alcohols has been provided in prior examples (see Patent Document 1) as a method that is less affected by temperature even at room temperature, significantly shortens the number of days required for preservation treatment, and allows for the long-term preservation of the original form of artifacts. The method for preserving excavated cultural artifacts using higher alcohols, as described in Patent Document 1, has already been provided by the applicant of this application.

Patent Document 1 describes two methods for preserving excavated cultural artifacts, consisting of the following steps: A first step involves immersing the excavated cultural artifact in a water-soluble solvent consisting of a linear or branched alcohol with 1 to 4 carbon atoms to replace the impregnation water of the artifact with the water-soluble solvent; a second step involves immersing the cultural artifact, impregnated in the water-soluble solvent, in a poorly water-soluble solvent prepared by adding a compound consisting only of saturated higher alcohols with 16 to 22 carbon atoms and alkylene oxides to a poorly water-soluble solvent consisting of a higher alcohol composition, in an amount that does not exceed the melting point range of the higher alcohol composition (limited to an amount that maintains the melting point range); and a third step involves solidifying the cultural artifact impregnated in the poorly water-soluble solvent.

Furthermore, the preservation method for other types of excavated cultural artifacts consists of a first step similar to the first step described above, a second step in which the cultural artifact, impregnated with the water-soluble solvent, is immersed in a poorly water-soluble solvent prepared in the same manner as above, thereby replacing 40% of the water-soluble solvent impregnating the artifact with the poorly water-soluble solvent, and a third step in which the cultural artifact, impregnated with the water-soluble solvent and the poorly water-soluble solvent, is frozen and dried under vacuum.

Patent No. 4634517

Incidentally, when preserving artifacts and other items according to their conditions of existence, state of deterioration, thickness, and material, it is necessary to carefully select various treatment conditions, such as the need for antibacterial and sterilizing properties of the preservation solution, and to apply a method appropriate to the object. Even in the method using higher alcohols described above, efforts and improvements are required to ensure that the higher alcohol penetrates deep into the tissue of the object and to minimize deformation and cracking of the object after treatment due to crystallization during solidification.

This invention was made in view of the current situation, and aims to provide a method for preserving artifacts, etc., that is based on the use of higher alcohols, and that, after preservation treatment, the treated object has a fine structure, is unaffected by humidity, ambient temperature, biological external factors, etc., even at room temperature, and is preserved for a long period of time without changing its state before preservation treatment.

The method for preserving plants, animals, or excavated cultural artifacts according to claim 1 of the present invention comprises: a first step of immersing the object to be preserved, which is a plant, animal, or excavated cultural artifact, in a water-soluble solvent consisting of a linear or branched alcohol having 1 to 4 carbon atoms to replace the impregnation water of the object with the water-soluble solvent; a second step of immersing the object, which has been impregnated with the water-soluble solvent by the first step, in a poorly water-soluble solvent consisting of a higher alcohol mainly composed of saturated alcohol with a melting point of 50 to 70°C, a cationic surfactant, and lignophenol or lignocresol to replace the impregnation water-soluble solvent of the object with the poorly water-soluble solvent; and a third step of solidifying the object, which has been impregnated with the poorly water-soluble solvent by the second step. For convenience, this preservation method will be abbreviated as "Preservation Method 1".

The method for preserving plants, animals, or excavated cultural artifacts according to claim 2 of the present invention comprises: a first step of immersing the object to be preserved, which is a plant, animal, or excavated cultural artifact, in a water-soluble solvent consisting of a linear or branched alcohol having 1 to 4 carbon atoms, thereby replacing the impregnation water of the object with the water-soluble solvent; a second step of immersing the object, which has been impregnated with the water-soluble solvent by the first step, in a poorly water-soluble solvent consisting of a higher alcohol mainly composed of saturated alcohol with a melting point of 50 to 70°C, a cationic surfactant , and lignophenol or lignocresol , thereby replacing at least 40% of the impregnation water-soluble solvent of the object with the poorly water-soluble solvent; and a third step of freezing and drying the object, which has been impregnated with the water-soluble solvent or poorly water-soluble solvent by the second step, under vacuum. For convenience, this preservation method will be abbreviated as "Preservation Method 2".

In the above preservation methods 1 and 2, the reason for including a first step of immersion in a water-soluble solvent before the second step of immersion in a poorly water-soluble solvent is that if the object is immediately immersed in a poorly water-soluble solvent, the impregnating water in the object does not smoothly replace the poorly water-soluble solvent, making it difficult for the poorly water-soluble solvent to penetrate to the fine details of the object's structure. Therefore, by performing the first step of immersion in a water-soluble solvent before the second step, as in preservation methods 1 and 2, the impregnating water in the object dissolves into the water-soluble solvent and smoothly replaces it. Subsequently, by performing the second step of immersion in a poorly water-soluble solvent, the water-soluble solvent impregnating the object is smoothly replaced with an alcohol-based poorly water-soluble solvent similar to the water-soluble solvent. This allows the poorly water-soluble solvent to penetrate to the fine details of the object's structure in a short time, thereby improving the dimensional stability of the object after treatment.

Furthermore, in the above preservation methods 1 and 2, in the second step, which involves immersing an object impregnated with a water-soluble solvent via the first step into a poorly water-soluble solvent, it is necessary to use a poorly water-soluble solvent, which is made by adding a cationic surfactant (soluble in higher alcohols) to a higher alcohol mainly composed of saturated alcohol with a melting point of 50 to 70°C, depending on the condition of the object. For example, it is known that if a brittle object or an object undergoing embrittlement is treated at a high temperature, the object is likely to deform or shrink, and conversely, if an object is treated at a low temperature, the object is likely to be affected by the ambient temperature after treatment, leading to a decrease in dimensional stability. To further explain this, although it is possible to treat objects in relatively good condition at relatively high temperatures, it is known that, due to the nature of the object, treatment at high temperatures above 70°C is likely to cause shrinkage or deformation. In contrast, when using higher alcohols with a melting point of 50°C or lower, there is a risk of the higher alcohol melting when the object is solidified via the third step (storage method 1) or when the object is frozen and dried under vacuum via the third step (storage method 2). Furthermore, it has been found that the processed object is more susceptible to external temperature changes. Therefore, it is appropriate to use saturated alcohols with a melting point of 50-70°C, selecting the appropriate alcohol depending on the processing temperature.

In the above preservation method 2, the substitution ratio between the water-soluble solvent and the poorly water-soluble solvent (a higher alcohol with a cationic surfactant) is sufficient if at least 40% of the initially impregnated water-soluble solvent is replaced by the subsequently impregnated poorly water-soluble solvent. Preferably, it is around 40-60%, and particularly preferably around 50%. When at least 40% of the initially impregnated water-soluble solvent is replaced by the subsequently impregnated poorly water-soluble solvent, the third step of freezing and drying the object under vacuum allows only the water-soluble solvent to evaporate and disappear from the object, while the poorly water-soluble solvent penetrates to the finest details of the object's structure, improving the dimensional stability of the object after treatment.

When preservation methods 1 and 2 involve treatment using higher alcohols, specifically the second step of immersion in a poorly water-soluble solvent prepared by adding a cationic surfactant to a higher alcohol, the treated object may exhibit a white appearance. This phenomenon hinders the preservation of the object while maintaining its original form before excavation. Therefore, to address this issue, it is desirable to add naturally derived lignophenol or lignocresol to the poorly water-soluble solvent for color correction, and to use these lignophenol or lignocresol in combination with a cationic surfactant that has bactericidal or antibacterial properties. By adding a cationic surfactant with antibacterial and bactericidal properties to a higher alcohol, and, in some cases, using naturally derived lignophenol or lignocresol, which is said to have termite-resistant and preservative properties, as a supplement or color corrector, the penetration into the object is improved compared to using only a higher alcohol, resulting in improved dimensional stability of the treated object. Furthermore, if the object is a plant or animal, preservation stability is also improved.

The method for preserving plants, animals, or excavated cultural artifacts according to claim 3 of the present invention is characterized in that the amount of cationic surfactant in the poorly water-soluble solvent does not exceed the melting point range of the higher alcohol. "An amount of cationic surfactant in the poorly water-soluble solvent that does not exceed the melting point range of the higher alcohol" means an amount of cationic surfactant added such that, even if the melting point range of the poorly water-soluble solvent changes due to the addition of cationic surfactant, the melting point range of the poorly water-soluble solvent does not exceed the melting point range of the higher alcohol.

The method for preserving plants, animals, or excavated cultural artifacts according to claim 4 of the present invention is such that the poorly water-soluble solvent is obtained by adding 2 to 15 wt% of a cationic surfactant to 85 to 98 wt% of a higher alcohol having 16 to 22 carbon atoms. If the amount of cationic surfactant added is less than 2 wt%, the effect of adding the cationic surfactant is difficult to exhibit, and if the amount of cationic surfactant added exceeds 15 wt%, it becomes difficult to secure the required amount of the poorly water-soluble solvent obtained by adding a cationic surfactant to a higher alcohol.

The method for preserving plants, animals, or excavated cultural artifacts according to claim 5 of the present invention is characterized in that lignophenol or lignocresol is added to the poorly water-soluble solvent in a maximum of 3% of the amount of cationic surfactant contained in the poorly water-soluble solvent. A mixture of a higher alcohol, which is a poorly water-soluble solvent, and a cationic surfactant may solidify. In this case, using a mixture of higher alcohols (a poorly water-soluble solvent) with a melting point in the range of 50 to 70°C, in which a portion of the cationic surfactant is replaced with lignophenol or lignocresol derived from natural products, prevents the formation of large crystals under temperature conditions and also prevents the occurrence of cracks. As a result, the poorly water-soluble solvent can be more reliably filled into the dense parts of the structure of the object, and a treated object in which the structure is completely replaced with the poorly water-soluble solvent can be obtained. This further improves the densification of crystals, dimensional stability, and preservation stability of the treated object, making it effective for preservation treatment of a wide range of objects. Therefore, in order to maintain the dimensional stability of the object after processing, it is optimal to use a mixture consisting of a higher alcohol mainly composed of saturated alcohol with a melting point of 50 to 70°C and a cationic surfactant soluble in the higher alcohol and having bactericidal and antibacterial properties, or a mixed composition in which a portion of the cationic surfactant having bactericidal and antibacterial properties is replaced with lignophenol or lignocresol derived from natural products, depending on the state of the object to be processed.

Furthermore, in preservation methods 1 and 2, it is also possible to add soluble fatty acid glycols with 8 to 12 carbon atoms, cellulose alkyl ethers, termite repellents, colorants, etc., to a composition containing a higher alcohol with 16 to 22 carbon atoms, a cationic surfactant, and a portion thereof substituted with lignophenol or lignocresol.

In this invention, the higher alcohols having a melting point of 50 to 70°C are those having 16 to 22 carbon atoms. Typical examples of such higher alcohols include the following:
Cetyl alcohol 70 (melting point 50-54°C, 70-75% C16 alcohol, 25-30% C18 alcohol)
Cetyl alcohol 50 (melting point 52-55°C, 50-55% C16 alcohol, 45-50% C18 alcohol)
Stearyl alcohol (melting point 57.5-59.5°C, C16 alcohol 20% or less, C18 alcohol 80-90%)
Behenyl alcohol 65 (melting point 65-70°C, 65-70% C22 alcohol, 20% or less C20 alcohol, 20% or less C18 alcohol)
Cetostearyl alcohol (melting point 54-56°C, 45-55% C16 alcohol, 45-65% C18 alcohol)

The cationic surfactant added to the above-mentioned higher alcohols having 16 to 22 carbon atoms and a melting point of 50 to 70°C is soluble in the higher alcohol and contains a saturated or unsaturated long-chain alkyl group having 8 to 22 carbon atoms in its structure. Examples include the following:
• Dodecyldimethylbenzylammonium chloride • Tetradecyldimethylbenzylammonium chloride • Stearyldimethylbenzylammonium chloride • Hexadecyldimethylbenzylammonium chloride • Octadecyldimethylbenzylammonium chloride • Oleyldimethylbenzylammonium chloride • Behenyldimethylbenzylammonium chloride • Cetylpyridinium chloride

Furthermore, lignophenols and lignocresols, which can be used by substituting a portion of a cationic surfactant containing saturated or unsaturated long-chain alkyl groups with 8 to 22 carbon atoms, are derived from lignin extracted from natural wood using phenol or cresol. They have an estimated molecular weight of 1000 to 5000 and a thermal pour point of 130 to 170°C, and are manufactured by Fujii Foundation Design Office Co., Ltd. at their manufacturing plant on Oki Island.

In this invention, the animals and plants included in the artifacts refer to all animals and plants as generally understood. Furthermore, excavated cultural artifacts include a wide variety of items excavated from various archaeological sites and burial mounds, such as products (wood fragments, dugout canoes, wooden vessels, etc.), metal products (circular mirrors, bronze bells, swords, fishhooks, iron tools, etc.), earthenware (pottery, etc.), animal products (textiles, human bones, animal bones, etc.), and excavated animal and plant materials (leaves, textiles, fruits, seeds, hemp, silk, lacquer coatings, etc.).

The present invention provides a method for preserving artifacts and other objects that, compared to methods using only higher alcohols as poorly water-soluble solvents, results in a more densely structured solid object after treatment. Furthermore, this method can be used for a wider range of objects, and the treated object becomes less susceptible to the effects of humidity and ambient temperature, enabling long-term preservation in its pre-treatment state. Additionally, a composition of a higher alcohol (a poorly water-soluble solvent) and a cationic surfactant, or a composition containing a higher alcohol and a cationic surfactant with some of the cationic surfactant substituted with lignophenol or lignocresol, forms a dense structure in the treated object. Therefore, the treated object does not absorb moisture from the surrounding environment, preventing problems such as aging and cracking. Moreover, treated objects with such characteristics, such as treated plants and animals, can be obtained in a shorter processing time.

This is a process diagram illustrating the method for preserving artifacts and other items according to the present invention. This is a process diagram illustrating another method for preserving artifacts and other items according to the present invention.

The invention will be described in further detail below.

In Figure 1, which illustrates preservation method 1, the first step involves immersing the object in a water-soluble solvent consisting of a linear (saturated) or branched alcohol with 1 to 4 carbon atoms, thereby replacing the water impregnated in the object with the water-soluble solvent. This first step results in an object in which the water contained in a supersaturated state has been replaced with the water-soluble solvent.

In the second step, the object impregnated with the water-soluble solvent via the first step is immersed in a poorly water-soluble solvent, which is a higher alcohol mainly composed of saturated alcohol with a melting point of 50-70°C, to which a cationic surfactant is added. This replaces the water-soluble solvent impregnating the object with the poorly water-soluble solvent. In this second step, lignophenol or lignocresol may be added to the poorly water-soluble solvent as needed. Furthermore, lignophenol or lignocresol may be added in place of a portion of the cationic surfactant contained in the poorly water-soluble solvent, up to a maximum of 3% of the solvent. By going through this second step, an object is obtained in which the water-soluble solvent has been completely replaced with the poorly water-soluble solvent.

In the final third step, the object impregnated with a poorly water-soluble solvent is cooled and solidified in air at room temperature and atmospheric pressure. This yields the processed object after the preservation treatment according to preservation method 1 is completed.

In Figure 2, which illustrates preservation method 2, the first step involves immersing the object in a water-soluble solvent consisting of a linear (saturated) or branched alcohol with 1 to 4 carbon atoms, thereby replacing the water impregnated in the object with the water-soluble solvent. This first step results in an object in which the water contained in a supersaturated state has been replaced with the water-soluble solvent.

In the second step, the object impregnated with the water-soluble solvent via the first step is immersed in a poorly water-soluble solvent, which is a higher alcohol mainly composed of saturated alcohol with a melting point of 50-70°C, to which a cationic surfactant is added. At least 40% of the water-soluble solvent impregnating the object is replaced with the poorly water-soluble solvent. In this second step, lignophenol or lignocresol may be added to the poorly water-soluble solvent as needed. Furthermore, lignophenol or lignocresol may be added in place of a portion of the cationic surfactant contained in the poorly water-soluble solvent, up to a maximum of 3% of the solvent.

In the final third step, the object impregnated with a water-soluble solvent and a poorly water-soluble solvent is frozen and dried under vacuum. This causes only the water-soluble solvent to evaporate and disappear from the object, resulting in a processed object that has undergone the preservation process described in preservation method 2.

Next, we will explain the examples with specific examples.

[Example 1 ]
Example 1 describes an example in which a piece of wood, an excavated artifact found at an archaeological site, is treated according to preservation method 2.

Preservation method 2 is almost the same as preservation method 1 up to the intermediate steps. Specifically, in the first step, the wood chips are immersed in tertiary butyl alcohol, a type of lower alcohol that is a water-soluble solvent, for one to several days. During immersion, all the water in the wood chips is replaced by tertiary butyl alcohol, resulting in wood chips in which all the water content within the wood tissue has been replaced by tertiary butyl alcohol. As the water content in the wood chips leaches into the tertiary butyl alcohol during immersion, the concentration of the tertiary butyl alcohol decreases. Therefore, the specific gravity is measured as needed, and the tertiary butyl alcohol is replaced with fresh tertiary butyl alcohol several times during the process.

As a pretreatment for the next step (Step 2), a mixed composition (melting point 60.19°C) of tertiary butyl alcohol (a type of lower alcohol), stearyl alcohol (a higher alcohol as described above), and 4.5% cetylpyridinium chloride and 0.5% lignophenol (both cationic surfactants) is dissolved in a constant temperature incubator at 62°C. The wood chips are then immersed in this mixture, maintained at 62°C, for several days. This pretreatment is intended to prevent cracking and shrinkage of the wood chips in the next step (Step 2) due to differences in concentration and molecular weight between the tertiary butyl alcohol and the higher alcohol, which is a poorly water-soluble solvent.

In the second step, a mixed composition (melting point 60.91°C) of stearyl alcohol (a higher alcohol as described above) and 4.5% cetylpyridinium chloride and 0.5% lignophenol (a cationic surfactant) is dissolved in a constant-temperature incubator at 62°C. The wood chips are then immersed in this mixture, maintained at 62°C, for several days. The immersion is terminated when approximately 50% of the tertiary butyl alcohol in the wood chips has been replaced by the mixed composition of stearyl alcohol, cetylpyridinium chloride, and lignophenol, and the wood chips are removed from the constant-temperature incubator.

In the third step, the wood fragments are rapidly frozen in a freezer, and then dried using a vacuum freeze-drying apparatus. While this completely sublimes and eliminates any remaining tertiary butyl alcohol within the wood fragments, the mixed composition of stearyl alcohol, cetylpyridinium chloride, and lignophenol remains within the wood fragment's tissue because it is a poorly sublimable solid. As drying progresses, the wood fragments solidify, ultimately yielding a solid, preserved object as treated in preservation method 2. This preserved object (wood fragment), a cultural artifact treated in preservation method 2, retains its original form from before excavation and can be preserved semi-permanently without deformation. Furthermore, the preserved object possesses the reversibility necessary for the preservation of this type of cultural artifact.

[Example 2 ]
This second example describes the case where rice of the Kame-no-o variety (7 days after harvest) is treated according to preservation method 1.

In Step 1, one rice plant (specifically, the "Kame-no-o" variety) is immersed in a water-soluble solvent, methyl alcohol, for several days. During immersion, all the water in the rice is replaced by methyl alcohol, resulting in rice plants where all the water content within the rice tissue has been replaced by methyl alcohol. As water leaches into the methyl alcohol during immersion, the concentration of methyl alcohol decreases. Therefore, the specific gravity is measured periodically, and the methyl alcohol is replaced several times during the process.

As a pretreatment for the next step (step 2), a mixed composition (melting point 60.19°C) of methyl alcohol (a lower alcohol), stearyl alcohol (a higher alcohol as described above), and 4.5% stearyldimethylbenzylammonium chloride (a benzalkonium-type cationic surfactant) is dissolved in a constant temperature incubator at 62°C. The pretreated rice is then placed in this mixture, maintained at 62°C, and immersed for several days. The reason for this pretreatment is as described above.

In the second step, a mixed composition (melting point 60.20°C) of stearyl alcohol, a higher alcohol, 4.5% stearyldimethylbenzylammonium chloride, a benzalkonium-type cationic surfactant, and 0.5% lignocresol as an auxiliary agent is dissolved in a constant temperature incubator at 62°C. The pre-treated rice is then immersed in this mixture, which is maintained at 62°C, for several days. This completely replaces the methyl alcohol in the rice with the mixed composition of stearyl alcohol, stearyldimethylbenzylammonium chloride, and lignocresol. After the replacement is complete, the rice is removed from the constant temperature incubator.
In the third step, the rice is cooled and solidified at room temperature to obtain the treated object (rice) preserved using preservation method 1. The treated object, a cultural artifact thus processed, retains its original form from before excavation and can be preserved semi-permanently without deformation. Furthermore, the treated object possesses the reversibility necessary for the preservation treatment of this type of cultural artifact.

Regarding dimensional stability, the lengths of 10 leaves along the leaf veins (vein-direction portion) and the portions perpendicular to the leaf veins (lateral portion) were measured for rice plants before treatment. These values were then compared with the lengths measured at the same locations for rice plants after treatment. The dimensional changes of treated objects (1) and (2) were similarly measured before and after treatment. This was done for both treated objects (1) (preservation treatment using a mixed composition of stearyl alcohol (a higher alcohol), stearyldimethylbenzylammonium chloride (a benzalkonium-type cationic surfactant), and lignocresol) (preservation treatment using only stearyl alcohol as a poorly water-soluble solvent).

[Dimensional changes]
Object after treatment: Leaf vein direction, transverse direction (1) 0.01% 0.1%
(2) 0.015% 0.2%

This shows that the treated object (1), preserved using preservation method 1, exhibits smaller dimensional changes in the vein direction and lateral direction compared to the treated object (2).

Claims (5)

The first step involves immersing the object to be preserved, which is an animal, plant, or excavated cultural artifact, in a water-soluble solvent consisting of a linear or branched alcohol with 1 to 4 carbon atoms, thereby replacing the water impregnated in the object with the water-soluble solvent.
The second step involves immersing the object to be preserved, which has been impregnated with a water-soluble solvent via the first step, in a poorly water-soluble solvent prepared by adding a cationic surfactant and lignophenol or lignocresol to a higher alcohol mainly composed of saturated alcohol with a melting point of 50-70°C, thereby replacing the water-soluble solvent impregnating the object with the poorly water-soluble solvent.
The third step involves solidifying the object to be preserved by impregnating it with a poorly water-soluble solvent through the second step,
A method for preserving plants, animals, or excavated cultural artifacts, characterized by comprising the above. The first step involves immersing the object to be preserved, which is an animal, plant, or excavated cultural artifact, in a water-soluble solvent consisting of a linear or branched alcohol with 1 to 4 carbon atoms, thereby replacing the water impregnated in the object with the water-soluble solvent.
The second step involves immersing the object to be preserved, which has been impregnated with a water-soluble solvent via the first step, in a poorly water-soluble solvent prepared by adding a cationic surfactant and lignophenol or lignocresol to a higher alcohol mainly composed of saturated alcohol with a melting point of 50 to 70°C, thereby replacing at least 40% of the water-soluble solvent impregnating the object to be preserved with the poorly water-soluble solvent.
The third step involves freezing and drying the object to be preserved, which has been impregnated with a water-soluble or poorly water-soluble solvent, under vacuum, via the second step.
A method for preserving plants, animals, or excavated cultural artifacts, characterized by comprising the above. A method for preserving plants, animals, or excavated cultural artifacts according to claim 1 or 2, wherein the amount of cationic surfactant in the poorly water-soluble solvent does not exceed the melting point range of the higher alcohol. The above poorly water-soluble solvent is obtained by adding 2 to 15% of a cationic surfactant to 85 to 98% of a higher alcohol having 16 to 22 carbon atoms, as described in any one of claims 1 to 3 , for the method of preserving plants, animals, or excavated cultural artifacts. The method for preserving plants, animals, or excavated cultural artifacts according to claim 4 , wherein lignophenol or lignocresol is added to the poorly water-soluble solvent in a maximum of 3% of the amount of cationic surfactant contained in the poorly water-soluble solvent.