Every prospector has his or her own opinion as to the best material to have under the riffles of your sluice box— 
Deep V Matting, Carpet, or Miners Moss. There is no single right answer just like there is no single right answer for which brand or size of sluice to use— the one you take to a beach for fine gold recovery is probably not the same sluice you should use in a river when shoveling in unclassified material.
- Carpet holds onto the finer gold particles when wet, making cleanup harder. To get every bit of gold, dry the carpet in the sun, then later shake it over a gold pan or tub to ensure you collect every grain of gold.
- Miners Moss is a good choice for stream sluices. It will help catch the gold and let the larger waster material run over the top and out of the box. It’s also great for collecting super fine gold. Miners Moss has two weaves— use the larger side when bigger gold is present, and use the tighter weave on the back side at the beach or anywhere you tend to find multiple sizes of gold.
No matter if you favor miners moss, matting, carpet, or a combination, using expanded metal over these materials can help create even more small pockets to help the fine gold drop out.
