Types Of Plasters Research Articles

Determining the impact of plastering materials on temperature distribution in lightweight concrete enclosure structures exposed to fire

The object of this study is lightweight concrete wall structures treated with various types of conventional plasters. The problem addressed in the paper is to determine the effectiveness of different types of plastering to protect walls from the effects of high temperatures and improve the fire resistance of structures. The samples of one series were fabricated by plastering the aerated concrete wall with a cement-lime plaster while the samples of the other series were plastered with vermiculite-perlite plaster. Samples of the third series were made without plastering (control series). In accordance with the research program, the distribution of temperatures under fire load was determined for all series. Studies have shown that wall structures plastered with verliculite-perlite mortar demonstrated 3.8 times better thermal insulation characteristics compared to plastering with cement-lime mortar. The fire protection effect of plastering (compared to non-plastered samples) for vermiculite-perlite solution was 6.3 times, and for cement-lime – 1.6. Adhesion failure was observed in cement-lime plaster under high temperatures, highlighting the need for additional fixing when applied to lightweight concrete walls. Theoretical analysis of the results revealed a discrepancy of up to 19 % with the experimental findings. The high thermal insulation properties of vermiculite-perlite plasters in comparison with cement-lime plasters are well known. A distinctive feature of this study is the quantitative determination of temperature distribution for the investigated plasters under conditions approximating real fire exposure. The findings of this research can be applied to the design of buildings and structures requiring enhanced fire resistance for wall systems

Analysis of Plaster Solutions for the Rehabilitation of Historical Buildings

Abstract Through this study, the analysis of 6 types of plaster suitable for the rehabilitation of historical monuments is proposed. The proposed types of plaster have superior thermal insulating properties compared to commonly used plaster. The study is purely theoretical and aims to compare the efficiency of each type of plaster when applied as a rehabilitation solution to a case study building. The case study building is an historical building located in Timisoara for which classical facade insulation system cannot be applied due to its historical status. Their analysis and comparison will be carried out from an economic perspective, thermal transfer and water vapour behaviour and impact on the energy consumption of the building. The purpose is to identify the solution that is the most cost-effective.

Preparation and Characterization of Anti-Microbial Wound Healing Materials from Natural Origins

Abstract Many types of polymers utilized as wound dressings, Polycaprolactone (PCL) displays high degree of biocompatibility as well as biodegradability, the mechanical strength states PCL in the foreground materials used in wound healing therapies. Current work aims to develop new types of wound plaster dressing, a multiple of natural and medical materials (aloe Vera, calendula and phenobarbital) were used to enhance the anti-microbial behavior as well as pain removal during wound healing period. Aloe Vera gels, Calendula extraction, with phenobarbital drug were precipitates on PCL layer in different percentage. Microstructure observation proves that polycaprolactone polymer is good base material supports dressing constituents, wound dressing homogeneity increased due to chemical reactions between the Aloe Vera and other materials. the main elements of dressing (carbon and oxygen) observed from chemical analysis (EDS) which is also showed that using combination of natural plants (aloe vera and Calendula) with phenobarbital medicine create wound plaster layer with wide range of active elements lead to therapeutic effects including antibacterial, In (FTIR) the results show using mixture of natural additives (aloe, calendula), medicine like phenobarbital in PCL lead to create wound plaster with high (OH) content acts to expedite the skin’s healing process by maintaining the natural level of minerals and hydration at wound area. Hydrophobicity of wound can minimized when adding some hydrophilic materials like Aloe Vera, phenobarbital and calendula, Aloe Vera gel, phenobarbital, as well as calendula decrease the contact angle value. Providing high adhesion between wound plaster and skin tissue. All prepared wound plaster has same and high resistance to Staphylococcus bacteria (40mm).

ИЗУЧЕНИЕ ПРОСТРАНСТВЕННОЙ ТОЧНОСТИ МОДЕЛЕЙ ЧЕЛЮСТЕЙ В ЗАВИСИМОСТИ ОТ МЕТОДА ПОЛУЧЕНИЯ ОТТИСКА И ЕГО МАТЕРИАЛА

Methods for obtaining working and auxiliary dental impressions of patients have been revised in recent decades, which is associated with 3D scanning. At the same time, the policy of import substitution in dentistry is also developing quite actively, which is reflected in the introduction of domestic impression masses for analog prints into public health institutions.
 The aim of study. Reducing the number of complications of dental orthopedic treatment by optimizing the approach to choosing a method for obtaining a working anatomical impression.
 Methodology. Impressions of the mandible of 10 patients were obtained. 7 impressions were obtained from each patient using the most commonly used techniques, silicone impression materials and intraoral scanning. Further, jaw models of 4 types of plaster were made for each impression and scanned with an off-site dental scanner. With the help of a micrometer in the oral cavity, measurements of teeth 3.5, 4.4 and 4.2 were made according to the maximum vestibular-oral size of the clinical crown, which were taken as a standard. The reference size is compared with the dimensions obtained on digital models according to the selected parameters with an accuracy of up to thousandths of a millimeter. A statistical analysis of the data obtained was carried out.
 Results. The data obtained confirmed the manufacturer's claims about the accuracy of the impression masses. A slight decrease in the studied sizes was noted on the models obtained by intraoral scanning. Whereas on models obtained using silicone impressions, the dimensions, on the contrary, were slightly larger than the reference ones. A statistically significant difference was revealed when comparing models obtained using intraoral scanning and models obtained by laboratory scanning from analogues of jaws using silicone impressions. When comparing the data obtained with the standard, no critical differences were revealed.
 Conclusions. It is impossible to unequivocally assert the advantage of a digital or analog method of obtaining impressions in modern orthopedic dentistry. The method of obtaining an impression should be chosen depending on the indications for a particular type of treatment and clinical conditions.

Experimental investigations on lime mortars reinforced with hemp braids

The need of experimenting sustainable components for building products is underlined by the prominent energy and raw material consumptions and carbon dioxide emissions for which the construction industry is responsible. Natural fibres, particularly hemp fibres, are worth of mention thanks to their acceptable mechanical properties and environmental advantages. The research aims to experiment two types of lime-based plasters reinforced with hemp braids, having different diameters, added in the mixture with different percentages. Two pre-mixed Natural Hydraulic Lime (NHL) mortars of M5 and M15 types, and three diameters of hemp braids (0.4 mm, 1 mm and 2.2 mm) in percentage by lime weight from 0.25% to 3% were considered. A first phase of the research consisted in physical tests to assess the amount of water absorbed by the hemp fibres to evaluate the plaster workability. Afterwards, only the mixtures with acceptable workability values were subjected to mechanical tests. The results of the laboratory tests showed that hemp braids produce a decrease in the workability of the plasters, that remains acceptable for low percentages of fibres. Compared to the unreinforced plaster, the braids allowed an increase in the flexural strength and a decrease of the compressive strength. In both mechanical tests it was evident the sewing and confinement effect of the fibres that led to a more ductile behavior of the mortar.

Design method for masonry structures retrofitted with steel reinforced plaster

In this paper an analytical approach for the design and assessment of masonry structures retrofitted with steel reinforced plaster (SRP) is proposed. The aim of the proposed method is to consider the main parameters affecting the performance of the strengthened wall (such as masonry properties, plaster properties, spacing and number of connectors) and provide a general formulation for practitioners to use in the design of SRP retrofitting interventions in place of the common empirically-based numerical coefficients proposed by the Italian Standard. The approach is developed starting from the experimental results of diagonal compression tests performed on clay brick walls retrofitted with SRP presented by the authors in previous studies. The maximum load is analytically predicted considering that the plaster and masonry layers work in parallel. A validation is conducted using additional experimental data available in literature. The obtained formulation is able to approximate the experimental values, being on the safe side against them in most of the cases. It is important to note that the method has been developed and validated using a limited number of experimental results. For this reason, adjustments may be needed for different types of masonry, plaster or anchor configurations.

Comparative assessment of physical and mechanical indicators of packing materials of complete removable dentures

Successful dental rehabilitation of a patient with complete removable dentures depends not only on a number of features of the selected design and clinical conditions of the patient's prosthetic area. Also on the manufacturing technology of the materials used for its manufacture. The purpose of our study was a comparative assessment of the physical and mechanical properties of doped packing materials for removable denture structures using an improved method. An alloyed packing material based on gypsum and supergypsum, modified with nitrile rubber latexes and organosilicon emulsion, was developed. The selected modifiers differ in their structure, group polarity and lyophilicity. The comparative analysis of the quality of auxiliary dental materials included a generalization of the results of a laboratory study of the physical and mechanical properties of various types of plaster. In the system of qualitative assessment of plasters, the indicative properties of auxiliary materials were investigated: "ORTHOGYPS", "Gypsum highness type 10", "Base Stone", provided by ISO 6873, which are divided by us into technological (defining features of the material packaging process) and physical and mechanical (total working time, structuring time, relative expansion during structuring, relative expansion after structuring, compressive strength, linear shrinkage). As a result, it was determined that the developed modified components of the alloy packing material, in turn, provided acceptable accuracy of the base of the removable dentures, which corresponded to the working model due to the improvement of the physical and mechanical properties of the packing material and, as a result, improved manufacturability of removable orthopedic structures of dental prostheses. Keywords: orthopedic treatment, physical and mechanical properties, complete removable dentures, modifier, gypsum mixture.

Parameters of thermal performance of plaster blocks: Experimental analysis

This work aims to obtain parameters of thermal performance of various types of plaster blocks for vertical sealing. The methodology consisted of making test elements with 8 types of plaster blocks, in addition to plasterboard of different densities. Thermal resistance, transmittance, capacity, and delay were calculated, according to the Brazilian standard NBR 15220. Thermal behavior tests were carried out with controlled heating through a heat source, digital thermometer, infrared thermography, and an instrumented thermal chamber developed for this work. The experimental results corroborated with the trend indicated by the calculated parameters. The massive and hollow blocks of 100 mm had the best results followed by the 76 mm hollow blocks. The 50- and 70-mm massive blocks were among those with the worst thermal behavior. The study through the thermal chamber and real test elements associated with the normative methods allowed the practical verification regarding the thermal behavior of the components.

Dolomite in archaeological plaster: An FTIR study of the plaster floors at Neolithic Motza, Israel

Material studies of ancient plaster can provide invaluable information on pyro-technological advancements, living practices, stylistic preferences and possibly the cultural organization needed to produce the plaster. Past studies have established methods of analysis for calcite and gypsum-based plaster, but studies of dolomite-rich plaster can be more complicated. In particular, the useful FTIR-based method for determining the structural organization of calcite, which differentiates pyrogenic and geological calcite, is hindered by the overlapping calcite and dolomite peaks. Therefore, a new FTIR-based calibration is presented for quantifying the dolomite percent of the carbonates. This was tested both on known mixtures and in comparison to XRD analyses of ancient plaster. Weighted mixtures of calcite and dolomite were used to demonstrate the problem that dolomite causes when using FTIR to study calcite’s structural order. Limits were established for when dolomite can be considered a small error versus when additional steps must be taken, such as a density separation step to separate disordered calcite from dolomite-rich samples. These methods were applied to a case study of red-painted plaster floors from PPNB Motza. Two types of plaster were found: the plaster preparation layers which contained large aggregates and, based on the new calibration, a high percent of dolomite and some sediment, while the finishing topcoat was almost pure calcite with finer aggregates. The same technology persisted across the examined PPNB building phases. Additional examination by light microscopy was able to clarify the outlier results and provide possible insight on the use of a sunken floor or basin. These methods can now be applied for comparison studies of plaster across sites and time periods, and could also be useful in geological studies where mixtures of calcite and dolomite are present.

Thermal Characteristics of Fireproof Plaster Compositions in Exposure to Various Regimes of Fire

The problems of the fire safety of oil and gas facilities are particularly relevant due to the increasing complexity of technological processes and production. Experimental studies of steel structures with three different types of plasters are presented to determine the time taken to reach the critical temperature and loss of bearing capacity (R) of the sample, as a result of reaching a rate of deformation growth of more than 10 mm/min and the appearance of the ultimate vertical deformation. The simulation of the heating of steel structures showed a good correlation with the results of the experiment. The consumption of the plaster composition for the steel column was predicted, which allowed a 38% reduction in the consumption of fireproofing. It was found that to obtain the required fire resistance limit, it is necessary to consider the fire regime and apply plaster compositions with a thickness of 30–35 mm, depending on their thermal characteristics. The dependence of thermal conductivity and temperature on density is obtained, showing that the use of plaster compositions with a density of 200 to 600 kg/m3 is optimal to ensure a higher fire resistance limit. It is shown that the values of thermal conductivity of plaster compositions at 1000 °C are higher by 8–10% if the structure is exposed to a hydrocarbon fire regime. It is shown that the values of the heat capacity of plaster compositions at 1000 °C are higher by 10–15% if the structure is exposed to a standard fire regime.

Effect of different strengthening materials on tensile behaviour of plasters and renders

The purpose of strengthened plasters (interior applications) and renders (exterior applications) in this paper is to control cracks at the interface between the main structure and the infill wall rather than strengthen masonry and reinforced concrete structures. Cracks in plasters and renders have caused severe issues that need to be resolved urgently. Cracks affect not only the aesthetics but also the normal use of a building. The presence of cracks changes the perceptions of the owners of a structure, forcing them to question its safety and even take legal action against its developer. Consequently, the present paper discusses the effects of different strengthening materials on the tensile behaviour of plasters and renders, particularly on the first cracking. One test group without strengthening materials and six test groups with strengthening materials were tested under uniaxial tensile loads. Each experimental group included the same six specimens. A glass fibre-reinforced polymer (GFRP) grid, two types of basalt fibre-reinforced polymer (BFRP) grids, and three types of welded wire meshes (WWMs) were selected as the strengthening materials in the tests. Four types of plasters and renders were used: cement mortar, anti-crack mortar, gypsum plaster, and thermal insulation mortar. The crack pattern, stain–stress relationship, first cracking strain, energy dissipation capacity in the uncracked stage, and microstructure were investigated to gain better insight into the tensile behaviour of the plasters and renders. It was found that a strengthening material with a small mesh size resulted in numerous cracks and a narrow crack spacing. The stress–strain curves of the strengthened specimens could be divided into uncracked and cracked stages. The higher slopes in both stages of the strengthened specimens could be attributed to the higher longitudinal strain coefficient, smaller opening size, and larger cross-sectional area of each strand of the strengthening materials. The first cracking strain of the unreinforced specimen was smaller than that of a strengthened specimen. Stronger bond strength between plaster/render and strengthening material, smaller mesh size and greater cross-sectional area of each strand of strengthening material led to the larger first cracking strain. The energy dissipation capacity in the uncracked stage of the strengthened thermal insulation mortar was the least. The energy dissipation capabilities in the uncracked stage of the plasters/renders reinforced with BFRP grid-2 and WWM-3 were the second-highest and highest, respectively. The bond strengths of the GFRP and BFRP grids to the plasters/renders were stronger than those of the WWMs. The bond strengths between the gypsum plaster and the reinforcing materials were the highest, whereas those between the thermal insulation mortar and the strengthening materials were the lowest. Additionally, stress–strain relationships were proposed for the strengthened plasters and renders; the results were found to be in good agreement with the test results.

Possibility of producing thermal insulation materials from cementitious materials without foaming agent or lightweight aggregate.

Due to the high increase in the consumption of building energy in the world, it is urgent to develop and use thermal insulation materials to limit the demand of energy. In this article, the possibility of producing thermal insulation plasters from common cementitious materials such as fly ash (FA), metakaolin (MK), and silica fume (SF) without employing any foaming agent or lightweight aggregate was investigated. Either cement or gypsum was used as a binder material. Eight different types of plaster based on different pozzolanic materials were investigated and compared with the traditional cement mortar plaster (TC). The compressive strength, bulk density, total porosity, thermal conductivity, and thermal resistance were measured. The results showed that it is possible to produce thermal insulation plasters based on pozzolanic materials without including foaming agent or lightweight aggregate. The obtained insulating plasters exhibited low density (888.75-1575.63 kg/m3), high porosity (39.5-57.75%), low thermal conductivity (0.30-0.48 W/mK) and suitable compressive strength. Using gypsum as a binder material was better than cement for insulation purposes. SF showed the highest insulation efficiency followed by FA and MK.

Diagonal tensile tests on historical brick masonry wallets strengthened with fabric reinforced cementitious mortar

Masonry structures comprise a significant portion of the historical building stock all over the world. Previous studies have clearly pointed out that unreinforced masonry buildings are vulnerable against extreme loading conditions, such as seismic actions. Therefore, strengthening is inevitable in most cases for historical masonry to withstand severe loads. In this paper, the efficiency of fabric reinforced cementitious matrix is investigated experimentally by using diagonal tension tests. Fourteen wallets with a nominal size of 750x750x235 mm were produced with using solid clay bricks and a low-strength mortar. The bricks were collected from the structural walls of an early-20th century building under restoration. The low-strength mortar represents the historical mortar commonly used in similar historical brick masonry buildings located in Istanbul, Turkey. By testing the specimens under monotonic diagonal compression loads, the effects of different types of plasters on the wallet surface, varying types of fibers used in textile reinforcement and anchors used for the connection between FRCM and substrate are investigated. Although the wallet samples have inherent shortcomings in representing overall component response accurately, still the qualitative findings are enlightening the effectiveness of the FRCM system by increasing shear strength, stiffness (shear modulus) and dissipated energy of the masonry wallets. The strengthened specimens were failed due to shear sliding along a bed joint and/or by a stair-shaped separation while the refence specimens were failed due to the splitting of the specimen into two parts in the stair-stepped shape and a slipping through a bed joint.

Lightweight Vapor-Permeable Plasters for Building Repair Detailed Experimental Analysis of the Functional Properties.

Three types of lightweight plasters for building repair were prepared and tested. The composition of plasters was designed in respect to their compatibility with materials used in the past in historical masonry. For the hardened plasters, detailed testing of microstructural and macrostructural parameters was realized together with the broad experimental campaign focused on the assessment of mechanical, hygric, and thermal properties. As the researched plasters should find use in salt-laden masonry, specific attention was paid to the testing of their durability against salt crystallization. The mechanical resistance, porosity, water vapor transmission properties, and water transport parameters of all the researched plasters safely met criteria of WTA directive 2-9-04/D and standard EN 998-1 imposed on repair mortars. Moreover, the tested materials were ranked as lightweight plasters and due to their low thermal conductivity they can be used for the improvement of thermal performance of repaired masonry. The salt crystallization test caused little or no damage of the plasters, which was due to their high porosity that provided free space for salt crystallization. The developed plasters can be recommended for application in repair of damp and salt masonry and due to their compatible composition also in historical, culture heritage buildings. The added value of plasters is also their good thermal insulation performance.

Clinical and Radiographic Outcomes Following Management of Benign Bone Lesions of the Hand With Calcium Phosphate Bone Cement

Background: Enchondromas are benign primary bone tumors that often occur in the hand. Surgical curettage is often indicated for symptomatic lesions, but controversy exists regarding whether and how best to fill the void. Autograft and allograft bone in addition to various types of plaster or cement are common means addressing the postexcision defect. This study reports long-term clinical and radiographic outcomes of excision with calcium phosphate bone cement (CPC) for benign bone lesions of the hand. Methods: This is a retrospective review of symptomatic benign bone lesions treated with curettage and CPC by a single surgeon with long-term follow-up. Following Institutional Review Board approval, consenting patients returned for postoperative research visits, during which radiographs were taken and functional outcome scores were measured. Results: Of the 7 patients who consented to participate, all initially presented with pain at the site of the tumor. Average follow-up time was over 6 years and overall functional outcome scores were good with early return to work. Cementation filled nearly the entire lesion on postoperative films and there were no postoperative fractures, infections, wound problems, or revision surgeries. Conclusions: This study reports good long-term radiographic and functional outcomes, without recurrences, in a series of patients with symptomatic benign bone lesions of the hand when treated with excision and CPC by a single surgeon.

Uticaj načina pripreme na mehaničke karakteristike gipsa

Introduction: Plaster is widely used in dentistry for the production of master casts, as a binder in investment materials and as an auxiliary material in the laboratory stages of denture production. Due to its brittleness, there is a constant need to improve its mechanical properties. In this regard, in the research we started from the assumption that increasing the proportion of powder during the preparation of plaster improves its mechanical properties. The aim of this research wasto determine the significance of the change in the ratio of powder and liquid to the mechanical characteristics of plaster (compressive strength). Material and methods: Three types of plaster were used in the research: type 2, 3 and 4. For each type of plaster, three samples were made with different ratio of powder and amount of water (n = 9). After 24 hours, the samples were analyzed at the Faculty of Mechanical Engineering in Niš, on a universal testing machine. Results: Plaster type 2 showed the lowest values of compressive strength, and higher values of types 3 and 4, regardless of the ratio of plaster powder and water. As the powder content increased, the compressive strength of the samples increased. Conclusion: In order to improve the compressive strength, the proportion of powder in the liquid phase can be increased during the preparation of the material without visible changes in its structure.

Experimental Study on Capillary Migration of Water and Salt in Wall Painting PlasterA Case Study at Mogao Grottoes, China

ABSTRACT The plaster of the wall paintings at Mogao Grottoes is all made of earth, and the migration of water and salt in this kind of plaster is one of the most important factors that cause the deterioration of the wall paintings. However, the characteristics of the migration in the earthen plaster, which are quite crucial for the research on the formation mechanism of deteriorations and the conservation treatments, have not been fully comprehended yet. In order to study the migration rule of water and salt in the plaster, different types of simulated plasters were made according to the material composition of the plaster at Mogao Grottoes. Through a series of experiments and analyses, pore-size distribution, microstructure and capillary migration rules of the plasters were characterized. Due to the difference in capillary performance, a capillary barrier effect will occur at the interface between the coarse plaster and the fine plaster. After the capillary migration, the salt is more likely to accumulate on the area of the capillary front, which will directly damage the paint layer. And the salt-water migration process inside the plaster will make the plaster structure loose and porous. Therefore, it is important to prevent rain infiltration and the rising damp after rainfall for wall painting conservation.

The Influence of Two Natural Reinforcement Fibers on the Hygrothermal Properties of Earthen Plasters in Mogao Grottoes of China

Murals in Mogao Grottoes consist of three parts: support layer, earthen plasters and paint layer. The earthen plasters play a key role in the preservation of murals. It is a mixture of Dengban soil, sand, and plant fiber. Two different natural fibers, hemp fiber and cotton fiber, were reinforced to earthen plasters in the same percentage to evaluate the influence on hygrothermal performance. The two types of earthen plasters were studied: one containing hemp fiber in the fine plaster (HFP) and the other containing cotton fiber in the fine plaster (CFP). Specific heat capacity, dry thermal conductivity, water vapor permeability, and sorption isotherms were investigated. The results showed that the difference between two natural fibers has much more impact on the hygric properties (water vapor permeability and sorption isotherms) of earthen plasters than on their thermal performance (specific heat capacity and dry thermal conductivity). The CFP with higher density has higher thermal conductivity than the HFP with lower density. But no significant differences of specific heat capacity were observed. Compared with HFP, CFP used in murals can reduce the rate of water transfer and prevent salt from transferring water to the mural surface. The overall findings highlight that all these features of CFP are beneficial to the long-term preservation of murals. The study of the earthen plasters in Mogao Grottoes is of general significance, and the measured properties can be used to obtain coupled heat and moisture analysis of the earthen plasters and to dissect the degradation mechanism of murals.

Biodegradation of Mineral and Silicone Plasters and Its Comparison

The article focuses on the determination of a fungal growth range on plaster depending on external conditions. The experiments compare three types of plaster which are the most widely used in Europe. The selected plaster is two mineral and one silicone. These types of plaster are standard mixtures developed and donated by manufacturing company from Czech Republic.The article contains comparison of germination and growth of mould on the surface of samples with the type of used degradation process before inoculation of mould. The types of used degradation were carbonation, freeze-thaw cycle, degradation by soil microorganism and high moisture. The microbial resistance was made based on modified Norm ČSN EN ISO 846. The samples were placed on mineral agar and in the 100 % humidity. The resistance of samples was evaluated by microscopy analyses.

Biological susceptibility of earth plasters: The influence of relative humidity on fungal growth

All building materials can be affected by microbiological agents during their lifecycle. The presence of microorganisms changes the appearance of the surface, degrading it, and they can even cause health problems to the residents. The biological susceptibility is dependent on the content of nutrient based on organic compounds. Thus one of the most susceptible of those materials are earthen construction materials. The degree of fungal growth is influenced by the chemical composition and plant fibres additives as well as the external conditions such as temperature and relative humidity. The earth plastering mortar has started to gain more attention recently as it is considered to have a low environmental impact and to increase the indoor air quality. Mechanical and physical characteristics of earth materials were studied by a number of authors but the knowledge about the biological resistance of the material is scarce. This study intends to look into the issue of the biological colonisation of earth plasters depending on the relative humidity. The samples, made of four types of earth plasters with different plant fibres, were placed to an environment of the relative humidity ranging from 33% to 100%. During a period of 4 weeks the extent of fungal growth was observed.