BS EN 15757:2010 pdf free.Conservation of Cultural Property—Specifications for temperature and relative humidity to limit climate-induced mechanical damage in organic hygroscopic materials.
BS EN 15757 In general, organic hygroscopic materials require a mid RH range as the extremes (high and low RH ranges), affecting the EMC, can result in structural damage, deformation and cracking.
However, a material that has been stored for significant periods of time even in a poor quality environment will have become acclimatised to the conditions. Careful analysis of the material’s needs is required to ensure that specified standard levels do not generate further damage.
Any change from a particular historical climatic environment may be problematic, even though the new conditions appear better for long-term preservation. If the change is sudden, the strain-stress may generate a climatic ‘shock’ leading to more intense levels of damage. Even if the change is slow, it may still generate stress and result in damage.
Therefore, the strategy of this standard focuses on maintaining the microclimate in terms of levels, seasonal cycles and fluctuations of temperature and RH, to which the materials have become acclimatized for a long time if this microclimate has been proved not to be harmful. Before a decision is made on the harmfulness or otherwise of pre-existing climatic conditions, the professional conservator involved in the project should carry out a condition report on the most vulnerable and/or valuable objects to be subjected to any environmental control proposal.
If the material has to be moved to a different climatic environment, then a careful, frequent monitoring of the condition of the material is necessary to detect symptoms of deterioration allowing stabilisation of environmental conditions which are appropriate for the needs of the materials.
When dealing with composite objects or when objects made of different materials occupy the same location,an evaluation of potential interaction between materials or parts of objects made of similar materials is necessary, as this situation is more complex. If there is synergy in the behaviour of the materials, the object as a whole may be more vulnerable than the most vulnerable of its component parts. However, the specifications concerning stability of temperature and RH and the importance of a careful consideration of the historical climate generally remain valid.BS EN 15757 pdf download.