Resin Properties (write up by mori.m)
title: Resin Structure
case: properties
type: resin in general
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resin = resin fiber + polyvinyl ether / polyester / epoxy
the higher the resin fiber, the stronger it becomes and harder to mold. polyvinyl ether / polyester / epoxy allows smoother mold, sanding and surface handling but invites 'micro cracking' which allows moisture intake. there is no 'perfect' resin grade, there are different grades for different users.
title: Sudden Climate Change and Plane Pressure
case: cracks, chipping, discoloration
type: high grade vs. low grade
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have been dealing with resins for the pass one year and so far i have encountered some cases of serious chipping and breaking of resin. did some research on resin properties and looking at the characteristics of resin, resin is basically made with two factors , volume and pressure. only with the correct pressure and constant volume, the resin would be able to have a strong hold and 'micro cracking' will be minimized. looking at the earlier batches of resin by some doll companies, their resin are lighter and more stiff unlike other better resin which have a higher volume/fiber adhesion that makes them more 'creamy' and easy to cut. being lighter and more stiff makes the doll more easier to sand or surface but NOT strong towards pressure, moisture or sudden climate change. i wouldn't know if you have ever brought your dolls on trips on a plane? cause the most worst condition is for example:
i am from Singapore, sunny, humid at times, takes my doll to Japan, which is like snowing and dry air on a plane ride. the following will occur:
hot (Singapore) -> pressure on plane -> cold (Japan) -> pressure on plane ->hot (Singapore)
the above factor will cause the condition of the resin to deteriorate and might cause it to become brittle and not durable to sanding or cutting. in an environment such as water or moist air, the micro-cracked surface will absorb considerably more water than an un-cracked surface. this will then lead to an increase in weight, moisture attack on the resin and fiber sizing agents, loss of stiffness and, with time, an eventual drop in quality properties. increased resin/fiber adhesion is generally derived from both the resin’s chemistry and its compatibility with the chemical surface treatments applied to fibers.
your dolls condition might be have already been threatened before it even it got to you, or perhaps due to traveling on planes and maybe of the country's climate change during the seasons.
in summary, weather, moisture and pressure plays important roles when it comes to the condition and discoloration of resin.
title: Staining of Resin Surface
case: dye stains, patches, yellowness
type: resin in general
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here is a tip, Do Not keep your dolls in an enclosed environment for too long a period of time. for example, in a bag with cushion padding. after studying and measuring the humidity levels of similar conditions with a elcometer, the readings show that the 'cushion padding' for the dolls actually retains most moisture in them. the 'enclosed environment' thus becomes damp. this causes the surface of the resin to become 'soft' and prominent to color dyes from clothes, bacteria and water. that is why most doll owners encounter the 'stained sculpt' and feet. most wigs and socks uses stretchable materials for their inner lining, and this material's color dye is likely to transfer upon contact with moisture. so if you leave the wig/socks on the doll when you store them away, you will notice that there will be dye stains on the resin over a period of time. the same environment also invites bacteria to grow on the surface, causing discoloration patches. excessive moisture also will cause the resin to turn yellow faster that the usual exposure to sunlight. In short, if you need to store your dolls over a period of time, remove all wig and clothing's off the doll and store them with dehumidifier crystals where possible. if not, take your collection out to 'air' often, in this case, dust is better than irremovable stains on the resin. where sunlight only discolors the surface of the resin, moisture degrades the resin from within, making it irreversible thru sanding.
mori.m