Permanent Modifications Primer [sanding, epoxy, dye]

DoA Mod Squad submitted a new tutorial:

Permanent Modifications Primer [sanding, epoxy, dye]

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Subtractive Modifications

Some collectors may choose to perform permanent, subtractive modifications on their dolls. This can be something simple, like removing the tips of elf ears to make human ears, and some can be more complex, like carving designs into the resin.
These mods are performed by removing parts of the resin, by either sanding it away with sandpaper, or removing large pieces with a rotary tool. The parts can then be finalized by giving a smooth finish with fine/high-grit sandpaper.

Types of subtractive mods:
Breast/genitalia removal or reduction
Elf ear removal
Eye opening
Sanding down a neck or the inside of a head for a better fit when making a hybrid
Seam removal
Slight restructuring of facial features or musculature
Carving designs into resin

Many people may sand a doll simply to clean up the sculpt and parts. Some dolls may have uneven eyes, or other symmetry issues that can be fixed by sanding. Some people may want to sand parts of a head to change features they don't like. And some people may want to modify a body to fit a certain character – for example, you can remove breasts from a female body to make a more feminine looking male body. Some people may want to add more definition to a body by enhancing musculature. Some people may want to have more drastic modifications, such as carving into resin. This can be used for any number of effects. You can carve small, light, decorative designs, or add scars. Or, you can remove entire chunks of resin from pieces, to emulate an old carved wooden box, or give a mech/robot effect.

Links and tutorials:
Seam Sanding
Bevelling eyewells
Opening eyes
Modifying elf ears into human ears
Breast Reduction tutorial

 

Materials to remove resin

Sandpaper

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Sandpaper is a simply, easy tool to remove small amounts of resin. It is good for buffing out light scratches or gouges, and can be used to remove the top layer of resin from a piece in de-yellowing efforts.
Sandpaper is measured in grit size - grit is the number of particles per square inch of paper, which is designated by numbers. The larger the number is, the finer the sandpaper's grit is - 400-grit is very coarse, but 1600-grit is very fine. Smaller numbered/coarse grit papers are good to remove a lot at once, but can leave large scratches. Larger numbers/finer grits will be less likely to leave scratches, but they will not sand much off at once, and you may end up polishing resin to a shine if you go too fine.
There are dry-only varieties, and wet-or-dry varieties. Using wet-or-dry sandpaper can be helpful, as dipping resin in water while working can remove dust from the pieces, and can keep the dust from floating around in the air.

To use:
Lightly rub sandpaper on resin in small, circular motions.

Warnings:
Always use a respiratory mask while sanding, as resin particulate can get into your lungs. Wet sanding can help avoid this, though it does not negate it entirely.

Rotary Tools

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A rotary tool is a type of electric, multi-purpose power tools suitable for the hobbyist. They are very well-suited for working on smaller surfaces that are not too hard, and do not require an extreme amount of torque. They make an ideal tool for working on polyurethane resin - specifically, for use in removing small amounts of resin that is impossible with sandpaper.
Dremel is the big-name brand of rotary tool, but there are other brands as well. There are also many different model types of tools; some have to be plugged in with a cord, which may or may not get in the way of work. Some recent smaller models can come cordless.
Hundred of different attachments are available for sanding, drilling, buffing, polishing and cutting. Make sure your tool and attachments are compatible, as not all attachments fit all types of rotary tool. For example: there are some oscillating saws/tools, which would be incompatible with the rotary-style tools.

Rotary tools can be purchased new from: Amazon.com, Home Depot and other hardware stores, other big-box stores may also have inexpensive models (Wal-Mart, Target, etc) - just be aware that cheaper tools are often inferior.

As some models of rotary tools can be expensive, watch for Black Friday specials and other discounts.

To use:
Here are some basic tips on using a rotary tool:
-Make sure to get appropriate respiratory and eye protection for use while working with a rotary tool. The speed of the tool will cause resin dust to quickly fly into the air, so you will definitely, absolutely get resin dust into your eyes and inhale it if you do not use proper protection.
-Make sure to use the proper bit for the job. Certain shaped bits are better at certain jobs.
-Make sure to clean your rotary tool after each use.

Very broadly, you will secure the bit in the tool first, then plug in the tool, and then turn the tool on. You will carefully press the tool against resin as it spins. You will need to hold the tool firmly to keep it aligned properly. You will drill out the area as you like, then dust it off and use sandpaper for a smoother finish.

Warnings:
Once again, make sure to use a proper mask when working with a rotary tool, as well as proper eye protection (safety goggles). The speed of a rotary tool will cause resin to fly off in any number of directions, and the dust can be an extreme irritant to both lungs and eyes.

For further information on using a rotary tool, the following WikiHow tutorial is very thorough.
How to Use a Dremel Tool

 

Additive Modifications

Some collectors may choose to perform permanent additive modifications on their dolls. This could include making eyes smaller or changing their shape, changing the structure of a face, or adding breasts or genitalia for a gender change. These modifications are done by adding some kind of clay on top of the existing resin.

Types of additive mods:
Adding breasts/genitalia
Adding elf ears
Closing eyes
Adding on to a neck for a better fit when making a hybrid
Adding raised designs onto resin

Many people get a BJD to fit a certain character they have in mind. In the case of fantasy-themed characters, some may have elf ears, horns, claws for hands, ridges on their heads, or other effects. Some people may modify their dolls to fit these characters if the doll is normally a human. Using different kinds of clay or epoxies, people can add elf ears on to existing ears, add claws onto fingers, and can even add scales onto faces and bodies. For non-fantasy mods, people can change the look of a sculpt by adding onto mouth, cheeks etc, to change features they don't like.

Links and tutorials:
Adding teeth
Adding claws
Adding elf ears
Closing eyes
Enlarging breasts

 

Types of epoxy or clay for additive modification

Epoxy is a polymer-based type of adhesive, usually a liquid material that comes in two parts. When the two materials are mixed, the chemicals in the materials bond together, to form a super-strong glue-like adhesive. In the case of BJD materials, epoxy is the general term for an epoxy putty - an air dry, clay-like material that has the adhesive strength of epoxy.
Epoxy putty cures to be rock-hard, and can be drilled, sanded, dyed, and painted. It can be scratched or gouged, but is overall equally as strong as resin. Acrylic paints can be added during mixing (or maybe ground pastels), to tint the epoxy to try to match the resin color. The opacity and texture will always be slightly different from the resin though, and will not take dye the exact same way, so it will not be a perfect match.

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Product: Epoxy putty
Brands to looks for: Aves Apoxie Sculpt & Milliput are the most popular
Where to buy it: Check each manufacturer's website for where to buy the item. Amazon is also a good place.
Correct usage: Mix epoxy according to manufacturer's directions. Press epoxy on to desired location, mold/sculpt to desired shape. Water can be used to keep the surface smooth, and the excess can be cleaned with water before it has cured. After curing, epoxy can be sanded for a finer finish and to smooth edges further.
Incorrect usage: Mixing parts incorrectly; not wiping excess epoxy before curing. Careless application can leave bits of cured epoxy in undesired locations, so cleaning up the excess is very important for a smooth finish. Try to avoid working with dirty hands - epoxy putty will attract and trap every type of dirt, dust, and lint, and it is very hard to remove any dirt from the putty after it has been mixed.
Possible damage: Getting epoxy in small nooks of a head will make it very difficult to clean out after it has cured. If you use water while sculpting, water with dissolved epoxy can get into nostrils, lip and eye creases, and in ears. It is important to make sure you are cleaning these areas carefully while still wet, otherwise a hazy residue will remain, and must be sanded out to be removed.


Some information on specific types of epoxy putty and clay:

Apoxie Sculpt
Apoxie Sculpt is made by Aves: Aves Studio They make many varieties and colors of epoxy clay. The best option is their Super White Apoxie, because it takes color better when tinting. The regular white Apoxie Sculpt can be used, as well as all their other colors, but they will just be a different color, and take color differently when tinting.

Milliput
Milliput also makes a variety of epoxy putties. The best option is their Superfine White variety, as it is lighter-colored, and can be tinted better. They also have their standard yellow version, and a silver-grey version; both of which can be used, but again, the color will be more difficult to work with.
May dry faster than Aves brand, so may be harder to work with.

Less popular brands:
Amazing Sculpt Ultra Fine Synthetic Sculpting Clay at AmazingSculpt.com
Magic Sculp Magic Sculp
Dollmore epoxy putty - very dark yellowish-grey, may take longer than specified to cure fully.

Rarely used brands:
Bondo - meant for fiberglass/car use, seems to be very toxic while curing.
Tamiya - Tamiya offers two kind of epoxy putty, one that dries yellow, and another 'quick-dry' type that dries green. They do not seem to be very recommended, as they dry too quickly, and are brittle when dry.
Mr. Hobby Mr. Putty - very little information available


Other clay:
Polymer clay (Sculpey) - Some people have tried to use polymer as a material for additive mods. This is not recommended though, as polymer clay needs to be baked in order to cure, which can damage the resin. And even if the baking turns out alright, polymer clay does not stick to resin well, so the mod may just pop off.
Plumber's putty - Some people have used Plumber's putty to some extent. It is another 2-part mixable putty. Most varieties are grey, and they may be more grainy and have less potential for fine sculpting when soft.
Paper clay - generally too fragile for serious mods


General info and tips:
Sanding after the epoxy has cured will lighten the epoxy in most cases.
When using any kind of epoxy to make ears or nails or some other long shape, the putty may need some kind of armature, or may need to be sculpted in layers, to prevent the soft putty from bending or collapsing before it has cured.
It may be possible to smooth putty with rubbing alcohol - the alcohol will evaporate, without making the putty as wet as using water.
If not sculpting something directly on a doll, make sure to sculpt the piece on something bendable, or like tin foil or wax/parchment paper. The putty will stick to most items, so you will need to make sure you can take the piece off once it has cured.
Most epoxy putties may be too sticky right at the start - give them a few minutes to rest, and they should be less sticky and easier to work with.


FAQ: Apoxie Sculpt and other epoxy putties

 

Repairs

Sometimes a doll does not need a visual change, but rather, may need some modification to improve posing, or fix a problem with how an s-hook fits in the head, or make sure eyes fit properly in the head.
And sometimes, a doll may be damaged in some way. There could be a chip or crack, or large scratches or gouges that cannot be fixed by sanding. Many repair mods are done with epoxies. In the event of damage, or if a subtractive modification goes wrong, a modder can use epoxy to replace what was removed. They can also use dremels or sandpaper to re-modify a doll back to its original form if it has been added to with epoxy.

Sometimes epoxy can also be used to create replacement parts. If a joint peanut or some other small part is lost, epoxy can be used to replicate another part, which will be strong enough to be a permanent solution, if the part cannot be replaced through the doll's company.

Tutorials:
Fixing 'gappy' eye wells
Adding magnets to a headcap

 

Dye

Some collectors may decide they want their doll to be a different color. While some companies offer a wide selection of colors to choose from, not all companies do so. Sometimes, a person may want a very specific color that is simply not available from a company. A good way to achieve the color they want, is to permanently dye their doll a different color of their choice.

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Product: dye for synthetic materials
Brands to looks for: iDye Poly and RIT DyeMore
Where to buy it: Craft/fabric stores, online
Correct usage: Mix dye according to manufacturer's directions. Multiple colors can be used at the same time to achieve a different color. Use a stainless steel pot to avoid bad reactions with the dye.
Incorrect usage: Do not use cold water, avoid plastic or glass containers, do not submerge multiple parts at once.
Possible damage: If you do not dye pieces properly, they can look marbled, splotchy or streaky, or dye may not stick.

Avoid:
Glass or plastic containers. Glass on a stovetop is not recommended - glass in general is not made for stovetop use. Plastic will melt.
Depending on what dye you use, you may want to avoid aluminum or copper. Disperse dyes like iDye Poly and Rit DyeMore should not be affected by pot material, but if you choose to use a different type of dye, pot material may effect the result. Aluminum can become scratched and pitted from contact with dye. Copper may react with non-disperse-type dyes, causing a different color result.

Many thanks to Tokoz for her very thorough experimentation with and comparison of different brands of dye, including RIT, iDyePoly, and others:
Part 1 | Part 2 | Part 3 | Part 4 | Part 5

When dyeing your doll, you will always want to start by thoroughly cleaning every part. You may choose to lightly sand the entire doll to help it absorb more color. But keep in mind, if your sanding is uneven, the resulting dye job will also be uneven. Some people opt to spray a layer of sealant beforehand. This means the outermost sealant layer is what is dyed, so the dye job can be removed more easily if desired.
You will generally want to use a large, tall pot for dyeing, and make sure to have a pot designated for dye use only. If you use a pot to dye something, and then use it for food, chemicals from the dye can leach out into your food, possibly causing health issues.
Various manufacturers will have different recipes for their dyes, so you will mix their dye with their specific required amount of water. This solution will then be heated on the stove, and kept at the required temperature. Resin pieces should be tied to some kind of string, yarn, or other non-reactive material (so as to not change the composition of the dye itself), then dipped into the dye bath until the desired color is achieved.
You should then rinse the parts to remove excess dye, and then leave them to air dry.
You should do this procedure one piece at a time. If you put all the parts in at once, it will be hard to remove them all at once. This means that when one part reaches the color you want, some parts will stay in the solution longer, and parts that are left in longer will be darker, so you will not achieve a uniform color. It is best to time one piece until you get the color you want, then use that exact same time for each other piece.
Once the piece has been dyed and cooled enough to touch, a light washing or gentle scrub with a magic eraser may help even out some mottling/streaking before the dye has completely dried.

Link and tutorials:
Video tutorial on dyeing a BJD
Tutorial on dyeing your doll (photos are missing, but instruction is helpful)
De-zombification Serum - Resin Color Restoration (for yellowed dolls)