Drying and flattening paper – wiki electricity journal


Air Drying A support is air dried, without pressure, from a wet or damp state. The air dried sheet is often cockled. This cockling is due to the differential in shrinkage between wet, damp and dry areas of the paper. Air drying is often done on elevated screens so that both sides dry evenly. Blotters can use be used as a drying support but they tend to cause dramatic, local, cockling. Slant drying improves the drain–off somewhat and thus results in flatter, less cockled, supports. Slow air drying encourages the transfer of moisture within the sheet so that evaporation is more even. Slow drying is accomplished by controlling the humidity of the environment around the support gas x coupon 2014 to be dried, using:

This technique is used to encourage the preferential drying of a selected surface, e.g. the reverse. By turning a support face down on a non–porous surface, evaporation occurs principally on the reverse surface. Stains, if they might occur, would develop on the reverse. This also encourages stains to be drawn from the front (surface of slow evaporation) to the reverse (surface of fast evaporation) see drying on the suction table, see also stain removal electricity lesson plans year 6 on the suction table.

When a support is first removed from a bath it is very wet. If the moisture is not blotted away it will generally collect in pools, because the paper always cockles lightly when it is removed from a bath. Excess moisture will collect in these low areas slowing their drying rate, locally. The resulting minor stresses cause cockling electricity wikipedia simple english. Drying on a slant encourages the water to drain away evenly. The support should then dry evenly and possibly with only minor cockles.

Blotters and felts are used to absorb moisture from paper supports and hold them in a flat plane while the fibers are set (through the establishment of hydrogen ‘type’ bonds and physical entanglement which occurs during the various stages of drying) into their new configurations. Blotters and felts come in a variety of grades, qualities, thicknesses and densities. Blotters tend to hold a support flatter while felts allow it to move (somewhat). Weight is generally used to insure good contact with the blotter or felts and to reinforce the intended, new configuration. The length of time that a damp object stays within a stack of blotters or a pile of felts varies depending upon sheet dampness, hygro-expansivity and weakness (tears, folds, losses); the blotters or felts absorbency and slickness electricity invented timeline; and the weight of the stack/pile or dead weight resting on the object to be flattened. It is traditional to change the blotters or felts in contact with the support so that the drying process will proceed relatively quickly, release the hold the drying media has on the support so that the sheet can shrink (dry free of stress) or allow the object to be checked occasionally for unexpected problems. Common practice suggests that three blotter/felt changes are necessary with ever increasing blocks of time between changes, e.g., 15–60 min.; 30 min. – 4 hrs.; 2hrs. – several days.

There are many variations of this technique; although the technology is generally similar. The Japanese drying screen is the piece of equipment used for drying and flattening. It allows for the controlled evaporation of moisture from the support. Moisture generally evaporates from the exposed surface, but the surface against the paper membrane also evaporates at a much slower rate. Flattening is achieved because the margins gas news uk of the support are attached to the drying board while the support shrinks (dries). The Japanese screens have a semi-non-stick surface which allows continued use of the screen. Korean and Chinese screens are similar but do feature some differences. As the moisture evaporates the electricity magnetism support and lining shrink. This shrinkage causes the support to be pulled flat but also dry with built-in stresses. This can result in damage if the traditional Japanese drying/Flattening process are not considered: the Japanese climate is humid. Western climates are much less humid; therefore, drying on Japanese screens proceeds much more quickly, even violently, which can lead to curling at a minimum and damage if conditions are favorable.

The traditional Western adaptation of the Japanese techniques has been to dry lined supports face–in on the screen. This protects the image surface and stretches the lining causing flattening. The lining paper is stretched flat. The objects support is pulled flat because it is still damper than the lining. The objects support is pulled into an expanded state by the lining, is held in an expanded state; through its attachment to the drying board. The order of drying is: lining, paste, support, however it is not sequential (first one, then the next). The faster the drying rate (lower humidity) the more gas 4 less manhattan ks sequential; the slower the more even. Even drying results in linings that are dimensionally stable, usually don’t curl and have not subjected the support to severe stress. Face-in drying, after lining, allows the object’s support to shrink less than face-out drying, because the objects support is damper after the lining has taken its new configuration.

This is an adaptation of the preceding technique. It reverses the order of drying and allows constant viewing of the object during drying. In low humidity conditions this is vitally important because the object is subject to great stress and gas vs electric oven cost could possibly rip or be otherwise damaged. During face-out drying the object dries first, to a more normal dimension, and under less stress than with face-in drying. The shrinkage of the lining, later in the drying scheme, pulls the object’s support electricity formulas grade 9 flat. The order of drying of the object is: paste, lining, support (similar caveats about sequence apply). It is quite possible, if the hygro-expansivity of the lining and support are not matched, a curl will result; usually concave.

This is an adaptation of the above technique that takes into consideration the dangerously fast shrinking, drying and stretching of the lined support attached by its margins, under low humidity conditions, to a drying board. The margins between the area pasted to the board and the object are wet, usually with a brush, and kept wet so that the wet area will expand preferentially through the strain of drying, rather than damaging the support, weakening the support or stretching the support to a non-original size.

Directed hot dry air gas smoker recipes can be used to control the moisture content of paper or media. It should however, be used with great caution on paper supports, because permanent distortions from localized cockling can result. Control of the force of the air (blower motor control) and its temperature is desirable, but a skilled conservator can overcome these problems, especially in an emergency.

If media has started to bleed in a water bath or during a humidification process, it may be necessary to dry the support and/or media quickly to avoid additional bleeding or loss of media. The evaporating surface is the one the bleeding media will migrate to. If the media is moving and no other means is available to stop it (see “Small” suction tables) drying the reverse of the support will draw the media toward the reverse. This will minimize the effects of the damage or pull a stain away from the obverse. If the drying is done in stages it is possible to minimize the visual effects of the bled electricity distribution costs media. Lowering the overall moisture content of the paper will slow the bleeding. Keeping the paper moist will allow the bled media to be drawn to the reverse. Excess drying can result in additional damage due to cracking of media. If attempts will be made to reduce disfigurement, (after the emergency is over) the support should not be over dried because this will tend to set the damaged media. Localized applications of moisture, i.e., water on a small brush can be applied to the perimeters of the damaged design; capillary action will draw the water into the bleed area, if the reverse is then dried again the displaced media can be partially pulled gas near me open now to the reverse. Several attempts may be necessary. Severe damage to the design and support can result (loss of design, just more loss of design or setting of the bled media) if great skill is not practiced during this emergency treatment.

Localized drying can be used to reform or reshape a fiber mat (paper) that is “sprung” open or is distorted due to cockling, curling, rolling, folding or creasing. Drying a fiber mat sets it into a new configuration. If a damp area is dried, it shrinks locally. The remaining damp area around the dry area stretches to make up for the minute amount of lost space. This phenomena can be used to advantage to remove distortions.

In 2009, the Foundation for Advancement in Conservation (FAIC) launched the AIC Wiki with funding assistance from us electricity supply voltage the National Center for Preservation Technology and Training (NCPTT), a division of the National Parks Service. Along with catalogs from other specialty groups, the published Paper Conservation Catalog and the unpublished Book Conservation Catalog were transcribed into a Wiki environment. In 2016, the BPG Wiki Coordinators reformatted this chapter by removing the legacy numbered outline format and improving internal links.