Metal Casting Zone

I have only just started out in pewter casting as i would love to make small jewellery pieces and animal ornaments. all of my equipment consists of a small ladle, pewter, polymer clay and silicone that is heat resistant and reccommended for pewter casting. so far i have made i 1 half open backed mould and a two part mould, both have come out smooth with so surface marks at all. When i have tried to pour metal into either/both of the moulds i keep getting un uneven surface, it looks like small smooth bubbles so im not sure if air is getting trapped inside. On the 1 half mold i sometimes get a rough back on the open side as well. Can someone please help as i am starting to despair and i can find no book for sale in england on the subject. Thanks for any replies

Hi Chezzychick
Welcome to the exassperratting world of pewter casting. I know your disapointment. try try try again and no results..
Sounds like the moulds have been produced ok Depending on what you are casting the two part mould need good venting so as metal drops in air is pushed out, and pushed out quickly,if retarded air can cause a rough surface on your casting. Your moulds need to very warm, good surfaces will never be acheived in a cool or cold mould,
Now the bigger problem,,, How are you melting your metal??? and how much metal volume are you melting in your melt pot???? Good casting can only be had if you have a sizable volume of metal melted and held at correct casting temp. Yes this means equipment ,,Sorry But pewter casts well 50oC above it melting point or a little less sometimes. A electric melt pot with temp control, even if only a small pot is a necessaity. Melting a laddle over a gas burner is too hit and miss and doesen't give a correct constant metal temp causing holes in the casting if too hot. I think this may be your area you need to look in to .
I had this prop in 1990 when I started casting , all fixed when I bought a melt pot with temp controller. Hope this help you..

Thanks John, i really apreciate you taking time out to help me. I have put vent holes in my silicone molds and that seems to have solved one of the problems. i am going to buy a melting pot with a thermostat so hopefully that should solve my problem! thanks again

Glade To help
This area of metal casting temp caused my great problems when I started my spin casting in the early days. a difference of 5 to 10 degrees can be the difference between casting coming out or not. When moulds heat up temp can be lowered a bit.
One area you could look at for melt pots on a small scale is to visit a gun shop. many of the pistol shooters in clubs make their own lead shot .A friend of my fathers years ago was making his own shot one day when I visited, I never forgot the neat melting pot he was using ,these small melt pots hold around 1 to 2 lb of metal a small wire lever is pushed up to allow metal to pour from the bottom of the pot when the shot mould is held underneath. I purchased one of these pots at first and found it quite satisfactory to start with. When I started casting more items on a regular bases I upgraded to a thermo coupler and 15lb pot. they don't come cheap ,new, 2nd hand can sometimes be found. All the best and keep me posted on your casting .