Top Pour vs Side Pour sand casting

Joanne Tinley Author

You can set up a sand cast mould using the top-pour or side-pour method - but what are they and which one is best?

One of the most important pieces of sand casting equipment is the casting rings. The set I prefer can be used for both the top-pour and the side-pour method, but what exactly do those terms mean, and which one is best to use?

I absolutely love sand casting! It's such a fantastic way of recreating found objects in silver, and as you get more confident with the techniques you can also add textures, combine two different metals and even cast stones in place. I never get bored of opening up the mould to reveal the cast as you can never be exactly certain what the results will be!

One of the most important pieces of sand casting equipment is the casting rings, the frame into which the sand is packed. They come as a pair. To describe the general casting method very quickly, one side is filled with sand, the item to be cast pushed into that sand, and then the second ring is fitted on top and sand is packed firmly on top of the item. The two halves are then carefully pulled apart and the item is removed, revealing two halves of a mould. A sprue and funnel (the route the molten metal takes to the mould) are cut through the sand and air vents cut into the sand.

I use sets of rings made by Casting Clay Sales, a small Southampton-based business. They produce rings of different sizes and also provide the fine casting sand that I prefer. The two halves of the casting rings can be very easily and accurately aligned (very important!) using the grub screw on the side, and the sets that I buy have a hole cut into the side. It is this hole that allows these casting rings to be used for side-pour as well as top-pour castings.

So now that I've mentioned those terms again I really need to explain what they are and what types of castings they are best for! The setting up of the mould is almost the same for each method, but the way that the funnel and sprue are cut through the sand and so the orientation in which the mould sits when the molten metal is poured in to it differs.

A top-pour sand cast has a sprue and funnel cut through the top side of the mould, as shown in the photo on the right. It is especially important to pack the sand tightly into the mould as quite a bit of it will be cut away. If the sand is loose it could all fall apart! Once the rings are put back together ready for the molten metal, they are sat flat so that the metal can be easily poured into the funnel. This is set up is sometimes called a horizontal cast, because the mould sits horizontally as the metal is poured in.

The top-pour set up is often used when you don’t want to disturb the edges of a mould, for example the fluted edges of a button, or if there are stones laid against the bottom of the mould and you don’t want to risk disturbing them. The cast of the flower button shown here fits both of those criteria. If the sprue had been attached anywhere else but the back of the button it would have spoilt the shape of the lovely petal edges. Setting up as a top pour also meant that the stone stayed where I wanted it to.

A side-pour sand cast has half of the sprue and funnel cut into each of the bottom (male) and top (female) halves of the mould leading out to a hole cut in the sides of the rings, as shown on the right. It is important to make sure that the sprue in each half lines up so that the molten metal can pour in easily. I often add a small length of 3mm brass wire to my mould to create the sprue to make sure that it is aligned perfectly. This set up is sometimes called a vertical cast as the rings and mould sit vertically with the sprue upwards when the metal is poured.

The side-pour set up works best for thinner moulds as gravity helps to pull the metal down through the mould. The metal may not have spread fully around the thin ring shown here if a top pour set up was used. Using the side-pour method also helped to keep the stones sitting on what would become the top of the ring.

Now that you've found out what top-pour and side-pour castings are it's time to learn

all the wonderful ways you can use them to create your own wonderful cast work!

My Sand Casting ebook takes you though everything you need to know,

and includes all the tips for adding textures and stones that I share in my studio workshops,

plus how to finish your casts beautifully.

Click here to find out more!

Categories: casting, getting started, jewellery making tips, jewellery tutorial, tool talk