Frequently Asked Questions about Alginate

How much alginate do you need for your project?

Different jobs require varying amounts of alginate.

	Single hand cast in a bucket	1 pound
	Face Casting	3 to 5 ounces
	Head Casting, as described on our website	3/4 to 1 pound
	Torso Casting (pregnant bellies, etc)	1 1/2 to 2 pounds

For hand casting projects "in a bucket", there is one "BEST WAY" to determine how much water and powder you're going to need.

1. Choose a "bucket". Half gallon milk cartons work fine, cut-off 2 liter soda bottles work fine, various "Tupperware" food containers can work also. This selection is really up to you, but make sure that the hand or hands that you're going to cast fit inside comfortably but not too loosely. Any extra space will require extra alginate to fill. Too tight and the hand(s) might touch the inside of the "bucket" during the procedure and spoil the casting.

2. Fill your bucket with water. Have your subject(s) put their hand(s) into the water until they are in the position you will want them during the molding. Some of the water will pour out of the bucket as it overflows. This is correct.

3. Measure how much water you have left by pouring it into some container with markings on it or by weighing it. (You'll have to subtract the weight of the empty bucket to get the water weight).

4. Luckily, 1 pint of water weighs almost exactly 1 pound. That's 1/2 pound per cup, 2 pounds per quart and 8 pounds per gallon.

5. For a hand cast job you're probably going to want to mix at about 4 water to 1 part alginate (by weight)- so if you've got 2 quarts of water (4 pounds, then you'll need about 1.0 pound (16 ounces) of alginate. (HERE'S THE MATH PART: Divide the pounds of water by 4 to get pounds of alginate, then multiply that by 16 to get the number of ounces. Round off to the nearest ounce.)

How much water do I mix with my alginate?

Different types of jobs require different alginate mix viscosities. Fortunately for you, Accu-Cast has already taken this into account when formulating the various products.

The Thin, Flowable Alginates

A hand cast (in a bucket) should be done with a thinnish mix. This allows the alginate to flow well all around the hand to get good detail. The 370-SD, 380-CC, 390-S2 and 570-PVG formulas all mix up nice and thin at a 4 to 1 ratio (water weight to powder weight). You might even try a little thinner, like 4.25 to 1 and find that it works better for you. Just be aware that the thinner you mix alginate, the weaker it will be when it sets and the faster it will lose water and shrink.

The Thick, "No-Slump" Alginates

A face cast needs a thicker mix so the alginate doesn't flow off the face so quickly and so you can build up a thicker layer without developing "thin spots" on places like the bridge of the nose, etc. Our GENESIS, 590-IBG, 680-LS and the 880 formulas all mix up nice and thick at a 4 to 1 ratio (water weight to powder weight). You might even try a little thicker, like 3.5 to 1 and find that it works better for you.

What is the best way to measure the water an powder?

There are two ways to measure out the powder.

1. By Weight: (RECOMMENDED) This is the most accurate way to measure alginate. Alginate is a highly compressable (fluffable) powder. In its compressed state it can be almost twice as heavy as in its fluffed state. This is the main problem with measuring by volume.

2. By Volume: (IF YOU MUST) This is not nearly as accurate a way to measure alginate, but some guidelines can help.

If the alginate is compressed (if it has been sitting in its bag for some time), then a 1 to 1 ratio (BY VOLUME, meaning 1 cup to 1 cup) is about 3.5 to 1 (BY WEIGHT). This means that when the alginate is compressed, water is about 3.5 times as heavy as the alginate. For a face cast job, it would take 3 cups of alginate (7 ounces) and 3 cups of water (24 ounces) if the alginate is compressed.

If the alginate is fully fluffed, then a 1 to 1 ratio (BY VOLUME) is about 4.75 to 1 (BY WEIGHT). Fluffed alginate is considerably lighter than compressed alginate. This isn't quite enough alginate for a hand casting job.

In its "average" state (neither fluffed nor compressed) you can safely figure that about 5 parts water to 4 parts powder (by volume) is about 4 to 1 by weight.

Water weight is pretty simple to figure out from its volume.

Water Weight/Volume Ratios
	1 cup	0.5 pound
	1 pint	1.0 pound
	1 quart	2.0 pounds
	1 gallon	8.0 pounds

Volumetric Water/Powder Guidelines for Various Jobs- IF YOU CAN'T WEIGH IT OUT
	Powder	Powder
Job	(Compressed)	(Fluffed)	Water	Recommended Accu-Cast
Face Cast	1 cup	1 1/2 cups	1 3/4 cups	590-IBG, GenesisV, 880
Single Hand Cast	5 cups	7 cups	8 cups	390-S2, 380-CC, 570-PGV
Head Cast	7 cups	9.5 cups	9 cups	590-IBG, 680-LS, 880, GenesisX

What's the best way to mix the alginate for my job?

There are a lot of ways to mix alginate. Some are better than others. Alginate Mixing Videos HERE.

1. Mixing by Hand (literally)- Some people like to put the alginate and water into a bucket and mix it with their hand. This is the least efficient and messiest technique and generally results in the lumpiest mix. If you are very quick and strong you can mix up to about 1 1/2 pounds of alginate this way in a little over a minute (any more than that and you really should be using the Power Mixing Technique described below). You must keep mixing until the alginate smoothes out. Some lumps are inevitable, but these generally will not affect the final casting.

2. Mixing with a Kitchen Whisk- This technique works very well for alginate amounts up to about 1 1/4 pounds. More than that and it requires a REALLY strong arm. Put the alginate into a big bowl. Add about 2/3 of the water and whisk until the water is nicely incorporated into the powder. Then add the last bit of water and whisk it in. For a pound of alginate and 2 quarts of water, this should take about 1 minute.

3. Mixing in a Bag- This is the technique we use in our Hand Casting Kits. We sell "Mix-In-The-Bag" alginates or you can measure out your own. We use a 3-mil bag to keep it from breaking during mixing.

With this technique measure out your alginate into a sturdy plastic bag, pour the water directly into the bag and mix in the bag by rubbing the bag against a table or counter top. This works better for thinnish mixes as for a hand cast. It is pretty efficient and very neat, but there are a couple of things you MUST do to make this technique work.

First, you must have a flat table available. The actual mixing in this method consists of kneading, mashing, smashing and generally vigorous rubbing of the alginate mix THROUGH the bag. A flat tabletop really helps.

Second, after the water goes into the bag, you've got to get most of the air out of the bag before you start mixing. This means that you've got to push down on the bag, pinch the bag closed right at the top of the alginate/water mix, then grip the bag right at the top. Twist it a couple of times around your finger, then start the general Mashing, Smashing and Rubbing. You need to be able to flatten the bag out on your table without too much extra air in the bag so you can work out the dry lumps in the alginate as efficiently as possible.

Again, don't worry about a few small lumps in the mix. They very rarely affect the quality of the casting.

4. Power Mixing- The very best way to mix larger quantities (over about 1 1/2 pounds) of alginate is to use a power drill with a paint mixing attachment on it. We sell these "Jiffy Mixers" here on our site or they are available at any paint, home improvement or hardware store. DO NOT get the one that looks like a black hamster wheel. It is WAY too difficult to clean up afterward. The best one looks like an airplane propeller at the end of a metal shaft. It has a ring around the outside and two spiral blades attached to the ring. This one mixes very well and is fairly easy to clean.

Put the alginate and 2/3 of the water into your bucket and put the paint mixer in. Mix slowly until the water is completely mixed into the powder. Then increase the mixing speed. After about 30 seconds, add the rest of the water and continue mixing. To avoid mixing a lot of air into the alginate, make sure that air is not being sucked down the shaft of the paint mixer attachment. If it is, reverse the direction of the drill so that alginate is coming UP the shaft and down the sides of the bucket. Very large quantities of alginate can be mixed very quickly with this technique using a large Jiffy Mixer.