I was curious about this and I had some left over milk that my kid will not drink. I think it got all lipasey in the freezer and it’s past it’s best by date anyhow. Besides, she’s suspicious of anything not water in cups. So I had loads of milk to play with (I’d tried to donate it a while back but we got crossed signals and I didn’t try again). I live in New Zealand so the artist that does commissions in the US is not an option for me. Plus I’m a naturally curious person and I’ve done resin casting before (though of scientific specimens). So be warned, this is a long picture heavy post. The step by step procedures (with pictures) are at the end, after I explore some things that didn’t work (or worked not so well), so if that’s what you want, skip on down. I’m not going to do any commissions (as I said, I live in NZ), this is just a starter guide for those interested in DIY milk-resin work.

I found this but I thought I’d try a few other things as well

I tried plasticizing milk via the vinegar-casein method and it really did not work. My milk separated some, but the globules did not stick together. They were so tiny that they just passed through my ultrafine cheese cloth.  I’m not sure how it’s been done by other people. I know the Etsy artist who does commissions in the US and a French design company both have plasticized human breast milk. I know the Etsy artist uses relatively small quantities, and from looking at her work I’m quite curious as to how that much precipitate comes from the volume of milk she requests. I’ve made cheese in the past and I know how cow milk precipitates, so I’d expect even less from human milk. Perhaps some sort of dehydration method. Well, whatever it is, it’s an interesting trade secret.

This is my milk after adding rather a lot more vinegar than the cow milk plasticization recipe called for (and lemon juice when the vinegar failed to do anything).

Still pretty liquid. The image doesn’t show it well, but there were tiny tiny precipitates in there. They, however, did not stick together. I left it sit for a bit with not much change. And they went right through 2 layers of ultrafine cheesecloth. So chalk that up as a failure.

Anyhow, on to things that did work, in various ways.

So what you need:

• Polyester clear casting resin. Mine is called Klear Kast. I bought 500ml of it (about 2 cups). You can get this from craft stores and even auto body hobby shops. Make sure it’s clear. There are some resins that are white and opaque when they harden. By the way, this (500ml) was an excessive amount even for experimenting. 250ml (1 cup) should be more than enough for any milk casting project alone. You’ll even have enough with that for some other small projects. Only buy more if you plan on doing some deep casting (like making paperweights or something).
• Moulds. There are special resin casting moulds. They are kind of a heavy duty thicker translucent plastic. Again, check a craft store. I suppose you could try some of the cheaper chocolate or candy ones. I can’t really see any reason why not to use a chocolate or candy one. The resin does get hot and will melt things (left over resin setting melted the little plastic medicine cups I had mixed it up in), but surely something you pour molten candy or chocolate into would hold up? I don’t know. Use at your own discretion. The chocolate/candy moulds tend to have more intricate designs, which you may not want for your resin project.
• Small plastic or paper cups for mixing in-disposable.
• Popsicle sticks (or some other wide thing to stir with, aka something disposable eventually)
• Gloves, face masks and a well ventilated work area.
• Toothpicks
• Your milk (you don’t need much if you know how you want to use it, otherwise if you want to play around you may need more-also consider playing around with cow milk if your milk is in short supply). I’ll include volumes of how much I used for each process. Make sure you pasteurize your milk (by heating on the stove or microwaving it until it’s nearly boiling) before using. Otherwise any bacteria in there can continue to grow and turn your project all kinds of colours you may not have intended.

Things you don’t need but may want depending on what you want to do

• Commercial resin spray- (I found cooking oil left a bit of a cloudiness to some of my castings). I’d say you may only need this if you are working with a complicated mould. All of my shapes came out without using it.
• Dyes if you want them.
• Pictures, other beads, mementos, glitter etc.
• Modelling clay. I bought Sculpey (I let my daughter pick a color, she picked sparkly blue) because I had an additional idea in mind. If you just want milk shapes, you can get any, preferably oil based,  kind.  If you might want coloured shapes as well, get something that you can bake like Sculpey or Fimo. If you aren’t a very good sculptor, I’m not an artist, but I have done some sculpting, there are push moulds available for this type of clay.
• Plastic wrap
• syringe or eyedropper-disposable is best. You’ll likely want one for your milk and possibly another one for resin use. I got through all my testing, though I reused some, with less than 5 disposable droppers.

So the numbers are 1: My thawed microwaved milk, 2: toothpicks, 3: my casting resin, 4: toilet paper for wiping stuff up (didn’t have paper towels), 5: That’s a straw for getting out air bubbles (didn’t need it), a wide handled scoop which proved to be very handy for stirring things since I didn’t have any popsicle sticks, and plastic bags (for cleanup, but also because I didn’t have plastic wrap), 6: plastic droppers for dropping milk, 7: My clay shapes, 8: my mould, and 9: my plastic medicine cups for mixing in.

So here’s the thing. Preparation is key. Get everything you might want and do a dry run, without resin made up, before you make your resin up. The resin brands vary and some have as few as 3 minutes of working time once the catalyst is added/ the solutions are mixed.

You should make up your resin in very small batches as it will harden up and be unusable if you forget something or are doing anything layered. Stir the resin and the catalyst/hardener with a popsicle stick in the plastic cups (while wearing your gloves and mask in your well ventilated area). The directions on mine has how to make up various volumes. The smallest was 1 ounce (30ml), so I pre-measured that volume with a marking pen on the side of one of my plastic cups. Everything has clothespins on it because it was windy and stuff was blowing away.

There are a few ways to do this. You can have abstract patterns, swirls etc, or you can have shapes.

To make abstract swirls, layers you mix the milk in (along with dyes, glitter, other beads etc) right before you pour it in the mould. It will not mix well. Use a popsicle stick or toothpick to mix it as it’s in the mould even. You can also pour a layer of resin (or dyed resin), wait for it to set, and then pour a milk mixed layer, set, pour another layer etc for a layered look.

Here are some results where I mixed about 10-15ml of my resin with around 4ml of milk. I mixed it really well and after a bit got it to be only bubbly looking, but of a uniform color. I poured that into a few moulds. On the left picture you can see that from the 10-15mls with added milk I got 4 (3 shown here) whole shapes and a few partial dribbles (shown in other pictures below). The right picture is a closeup of the bubbly appearance of the mix. I have no idea how this will hold up long-term, but after a few hours it was solid enough to remove from the mould. It was however tacky and flexible for several days. In subsequent tests of this method I had gummy shapes after letting the pour set overnight. So when you mix your milk and resin you will need to A) add extra catalyst, B) allow it to set for several days. Generally, after 2-3 days the gummy ones had set fairly well and hardened off after a week. I don’t think this in itself is a good long-term piece of jewelery. The milk resin cast shapes seem a bit brittle in texture. Maybe embedded in resin or coated with another clear coat they would be fine. I did find that it casts up much harder (not gummy) if you increase the amount of catalyst. I made several milk mix castings that are white, bubbly and opaque this way. This will only work if you have the kind of resin where you add a smaller amount of catalyst, rather than the kind where you mix equal volumes of two solutions.

To make shapes:

Mould your shape out of modelling clay. You are going for a bas-relief effect within your resin mould. So if I were to make a heart I’d make it sort of flattish and only finish it on one side. Make sure it is nice and smooth. You also want it to be smaller than the perimeter of your mould, so there will be resin all along the edges. A deep shape also works better than a shallow one.

Here are the shapes I made. I kept it simple and smooth-edged. So hearts, starts, moons. Make sure you measure them to your mould. Will they fit inside?

Now  wrap your model in plastic wrap. I used freezer bags and rubbed out the lines. Plastic wrap is a lot better since the freezer bags tended to un-cling (from themselves, the clay etc).

Pour your resin to the level you’d like your shape at, or halfway. Deeper holds the milk resin mix better and makes more of a contrast in the finished product.However, you don’t want your resin to go over the top of your clay shape. It will be very difficult to remove. So a deep, but straight edged shape is best. Now, while the resin is still liquid, use toothpicks to hold the model in place, shape and plastic wrap side in the resin.

Allow the resin to set for at least 24 hours (cover it with something, like a clean box, and set it out of the way. You pretty much can not bring this stuff inside unless you like the smell of varnish and paint thinner. So garages are cool. If you don’t have one, put a box upside down with rocks on it over this outside for the night). Now,  remove the plastic wrapped modeling clay, which should pop right out (but you may need to dig out), and dropper, pour, or syringe your milk-resin mix in there. See below for what happens if you use straight milk (even frozen). Allow your milk resin mix to set for at least a day, if not several days. Now, pour (or dropper, droppers work well for this) another thin layer of clear resin on top (you can always make up more), sealing the milk in and fill the mould the rest of the way.Don’t be afraid to overflow your mould a bit. You can sand off any imperfections later on. If you want to do a layered thing, maybe a photo or other memento you can put the photo in first or after the milk, but there should be a layer of resin between them.

So here are the various photos and what I did

Round 1:

From top, clockwise: Milk resin mix large oval, resin with clay shape large oval, milk resin mix small oval, milk resin mix long bar, resin with milk resin mix swirled in long bar, resin with clay shapes rounded rectangle, resin with milk resin swirl hexagon, milk resin mix heart.

Shapes held in place with toothpicks-solidifying

Set up, in the mould, after.

These were the initial ones I did where I put the clay (oiled in one case) right in the resin. I thought the oil, or the oiliness of the clay would allow it to come out. Alas, after much digging I only got most of it out. And blue dusty stuff everywhere.

Here they are after removing as much of the clay as I could (still blue tinted, as you can see. So unless you want that, use plastic wrap!):

With milk in:

I put milk in the recessed bits and froze it overnight, then poured clear resin on top of it. The milk when it thawed rose up through the second layer of resin. So that’s why you don’t use plain milk. These would have turned out great if I’d used a milk resin mix. It’s a shame these had the clay sticking issue (and the further milk issue) as these turned out very crisp.Well, lesson learned, experimentation and whatnot.

After less than an hour:

After several hours:

So that’s why I recommend mixing the milk and resin before putting it in the bas-relief shape. It’s a bit bubbly looking, but produces a slightly cleaner end product. You can see the results of putting a previously cast milk-resin shape into a larger shape above the heart in the second picture above. See below for finished versions of everything I tried. Still only 4ml or so of milk (which can actually make rather a lot of castings with the 10-15ml of resin).

Here’s round 2 in the mould:

Clockwise from top: Clear resin with previously cast milk-resin embedded in it, bas-relief resin with pure milk shape (used straight clay, had to dig out, left blue residue), clear resin with clay shapes embedded, bas-relief round 2 with plastic wrapped clay 1, bas-relief round 2 with plastic wrapped clay 2, milk resin mix squares (2 of them), bas-relief resin with 2 pure milk shapes (again, blue residue), clear resin with milk-resin swirled in it (hexagon), bas-relief round 2 with plastic wrapped clay 3, 2 drop shaped milk resin shapes, and 2 long rectangular milk resin shapes, trapezoid clear resin with swirled milk resin.

Here are the results from a more successful round.

Here are the processes and finished products from all rounds:

So what ultimately worked well.

Bas relief casting and pouring a milk resin mix (~4mls milk to 10-15 ml resin) into the recessed shape.

How to do:

1. Mould your shape (that you want to be made of milk) out of clay and wrap it in plastic wrap.
2. Make sure the shape fits in your mould (resin shape) and pour resin prepared per manufacturers directions into your mould.
3. Place your shape supported by toothpicks into your mould, and make sure it is about halfway submerged in the resin. You don’t want it to be too much more than halfway or it will be difficult to remove.`
4. Allow to set. After 4-6 hours you may be able to remove your shape, but allow to set at least overnight before doing the next steps.
5. As you can see I’m reusing some of the plain milk experiment ones.
6. Do any cleanup (removing errant clay, plastic wrap etc, any scraping you feel necessary and so on)
7. Prepare a small amount more resin per manufacturers directions. Pour a smaller volume of it into a separate cup and add milk. I used 10-15ml resin and 4ml milk and had way more than I needed. I found 4ml milk in 10-15ml resin gave a uniform whiteness that still hardened up if I used extra catalyst. I also found that increasing the catalyst increased the setting speed. Mixing the milk and resin before adding the catalyst often gave a smoother mix.
8. Stir up the milk resin mix until fairly uniform. It may mix well and it may retain a bubbly appearance (like oil and water)
9. Pour (or dropper with a disposable dropper) some of this milk resin mix into your shape. Allow to set (You can pour clear resin over the top of this, but you risk the milk floating out) for a few hours if not overnight.
10. A few examples
11. Make up more clear resin per the manufacturers instructions and pour another layer, fully filling your mould, over the top of your milk resin mix. Allow to set at least 24 hours or per manufacturers instructions.
12. Drill any holes and you have jewelry.

Here are some examples of this technique. You’ll notice some surface imperfections from resin rundown, but those are easily sanded away with a fine sandpaper. Cast resin polishes up well. You’ll also notice that some of the milk shapes are quite light. This is due to the shapes not being deep enough. This is after something like 4 or more separate shape runs and over a month of work, so I was getting a little tired since I had some I liked fairly well. Now that I (and you) know what to do I’ll adjust my future shapes accordingly. Deep, and well away from the walls of the mould.

Setting a milk-resin mix shape into a larger clear resin cast

1. For this you will need a smaller mould whose shape fits inside a larger mould.
2. Prepare a small amount of milk resin mix. I used 4ml milk to 10ml resin which made several castings.
3. Stir until well mixed.
4. Pour into first mould. Allow to set at least 48 hours (this will be tacky and flexible when you pull it out)
5. Pour clear resin into second mould
6. Place milk resin shape into second mould. Push into position with toothpicks.
7. Allow to set
8. Drill holes and you have jewelery

I actually like the way this one turned out best in terms of opaqueness and general appearance. Too bad I didn’t have many interesting shapes that fit into other shapes!

Swirling milk resin mix into resin

1. Make up some clear resin per manufacturers instructions
2. Pour off a small amount to a separate cup and add your milk. Stir to mix.
3. Pour some clear resin into your mould shape of choice, but do not fill.
4. Pour some milk-resin mix into the mould.
5. Use a toothpick to swirl however you like it
6. Pour more clear resin on top
7. Allow to set per manufacturers directions
8. Drill holes and you have jewelery

Here are some various examples of this technique.

Now that I have spent over a month testing things (getting resin on my brand new camera at least it’s only on the screen) and writing this post here are some more photos of my finished products. Here are some of my favourite results:

There are 6 (3 matching pairs) cast milk resin mix,  3 swirled resin mixes (2 small ovals and heart), 2 bas-relief cast shapes (oval with heart and trapezoid with heart), and 1 cast milk resin inside clear resin (oval in oval).

A close up of the non-solid milk resin cast ones. Same as above.

These all still need some minor sanding and drilling…but no drill yet so I can’t show off finished products.

Other tips. If you wanted a dyed layer decide if you want an opaque or transparent dye and where you want it. If you want an opaque dye, for example, behind your milk shape, you’d proceed as I described until step 9, then dropper a circle (or other shape) of dyed resin on top of the milk resin mix, let that set, then finish off with clear resin. Similarly if you want the whole thing translucently dyed, just use that instead of clear resin. If you want beads, glitter, a photo or other memento do a mock-up of how things will fit together so you know what order to put things in the resin.