Update -- the cauldron finally broke!  We're pretty sure who did it, but that's not important now (and stop calling me Shirley) (either you get it or you don't).  We had it for the T-bird and the school, but not the house.  We were amazed by the number of tot'ers that asked what happened to it.  Anyway, we're going to take the opportunity this spring to redo it and make a few improvements.

This has been our signature piece.  It was actually one of the first things we ever used in the haunt.  The effect has an appearance just like the title says, a boiling cauldron of blood.

We have no construction pics, but we will describe its construction.  

Materials needed:

    1 small fishbowl (or large glass mayonnaise jar)

    aquarium sealer

    1 medium to large sized aquarium pump

    20 feet of aquarium tubing

    handful of 't' fittings for air hose

    handful of  suction cup holders for aquarium tubing

    1 small light bulb fixture

    1 lamp dimmer

    15 feet of lamp cord with a plug (male) end

    plastic 55 gal drum

    12 feet black heater hose (auto)

    black sheet or tablecloth

    building blocks or other suitable stand

    1 quart of red food dye

The drum is the sort that soap comes in, if you know someone who deals in commercial cleaning supplies, they can hook you up.

Turn the drum upside down.  Mark a line around the drum at the height you want your cauldron to be.  Cut around the drum with a sabre saw and a blade suitable for plastic.  It isn't crucial that the cut be 100% even, but try not to stray too far (later on, we'll hide the edge).  When determining the height of your cauldron, you must take 2 things into consideration: First, the deeper the cauldron is, the heavier it will be.  Water weighs 2lbs per quart - that adds up quickly!  Second, the deeper your water level, the more powerful your aquarium pump needs to be.  We made ours about 3 feet deep.  To gain some extra height, it is mounted on cement builder's blocks to raise it another 12-18 inches.  If the drum half you use has any openings, they will have to be sealed.  Unscrew them, add a generous coat of aquarium sealer or silicone RTV and screw them back on tightly.  Your basic cauldron is now prepped and watertight.

We went through a few mods from the original model. Tempting though it may be - DO NOT mount your light fixture in any pre-formed holes.  The inside of the drum will be irregular around these holes and a permanent seal WILL elude you. The best container for the job is a gallon mayonnaise jar - these are hard to find in glass these days, but any similarly shaped glass jar should do.  In a pinch, even an upside-down fishbowl can be used.   Take note: A jar with a screw on lid is preferred.  Presumably you are planning on replacing the bulb. If your cover isn't easily removable, you will be using foul language sometime in the future.

Find a relatively flat spot on the drum bottom.  The centerline will have a seam - you don't want it there.  Put a generous coat of sealant on the outside of the jar lid and stick it to the bottom of the drum. A few sheet metal screws will ensure it stays put. Also add a bead of sealant around the lid where the sides contact the drum.  When in doubt - add more sealant. 

Mount your light bulb socket in the center of the jar lid and drill a 3/8" hole beside it.  Remember that the jar will be screwed back on to seal things up, so do a test fit first, or the aforementioned cussing will start up again.  We've tried both white and red bulbs and found that a 40 watt red bulb is about right.  Once you have everything laid out, pass the lamp cord through the hole, wire the fixture, attach the fixture and screw the jar onto the lid. If you didn't distort the lid, the jar should seal perfectly. Give the sealant a day to cure.   Don't forget, the jar should be removable.  Now it's time to make that jacuzzi effect!

 Drill a ¼" hole in the bottom.  Pass the aquarium hose through this hole.  Every four to six inches put a 'T' fitting on (you'll need to cut the hose).  To mount the hose, you can get these nifty little suction cup holders for aquarium tubing at your local pet store.  If you don't mind getting messy you can even use epoxy or sealant to attach the tubing.  What you should end up with is a circle of tubing around the perimeter (but not right up against the side.  The 'T' fittings will send air bubbles up to give the appearance of a boil.  Seal the opening where the tubing passes through the bottom both inside and out.  Be generous.  Very generous.

Before actually using it, do a test run.  Fill it with enough water to cover the jar and let it sit overnight on newspaper.  Check to see if anything leaked.  Do not have the light bulb plugged in while doing this check.  Also have the free end of your air hose higher than the top of the water.  If it does leak, you can always add more sealant.

Now to 'dressing' the cauldron.  Our 55 gal drum was white.  We decided that the 'blood' looked better against the white than if we painted it black, so we didn't do anything to the inside.  For the outside, we took a black sheet and cut a hole in the center (it doesn't need to be perfect).  We then took a length of narrow radiator hose and sliced it lengthwise.  All you have to do is jam the hose over the lip of your cauldron and make sure it grabs a bit of sheet to hold it in place.  This also has the advantage that if you didn't cut you drum perfectly even or if your cut was ragged, everything is covered up. As mentioned earlier, we mount ours on some builder's blocks to get some height.  But not too much height, TOT’ers shoud be able to see the effect.

Now for the final hook-ups.  Run your aquarium tubing to your air pump.  If the pump is to be located below the waterline of the cauldron you MUST use a check valve.  We use a Rena 400, set to full output.  The first time you use it, twist the T connectors so they point in random directions.  Because of the nosie generated by the air pump, we mount it some distance away.  Somewhere along the lamp cord, you should put a dimmer.  An inline lamp dimmer directly underneath works great. You're now in business!

Soup’s on!

Notes:

We've tried several different formulas for our blood.  The key fact here is that you'll be adding it to a large volume of water.  Cool Aid smells like a big tub of  Cool Aid, and the color is all wrong.  Same thing with Karo syrup.  Use food dye, not clothing dye.  Those little vials you get in the supermarket won't cut it either.  You'll need to go to the warehouse club, or better yet, a restaurant supply.  If you can, get cake dye, not food dye.  However, all purpose food dye will work fine, you just may have to use a bit more.

The light fixture is optional, and we did try it one year without it when we didn't have enough extension cords.  The effect just isn't the same without an eerie glow coming out from under the water/blood though.

Depending on how powerful your pump is, you will not get a full 'boil' right away.  You will notice that it takes time until all fittings give out air bubbles.  As soon as the fittings are covered with water, start your pump.  When filling, be sure to stop a few inches before the top or when the pump hits full force, you'll start sloshing water over the sides.

When adding your food dye, go slow.  You can always add more, but it will be a major pain to lighten up the shade.  You going for a nice crimson shade, but remember if you make it too dark, it won't look like blood.  This is where the light fixture helps.

Drainage.  This is a big consideration.  Now I'm assuming you placed your cauldron somewhere where you can fill it with a garden hose, but just turning it over on it's side isn't very practical.  Ideally, your aquarium hose should be long enough to make it to the driveway or a drain.  When you unplug the pump, gravity will take over for you and send the water out the end of the hose.  It won't hurt your lawn, but the volume of water will, so if you drain on the lawn, move the hose around.  Whatever you do, don't drain this on concrete.  It will stain.  Of course, you may like having 'bloodstains' on your concrete....

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