In BSL we use English mouth patterns to help clarify some signs. This means we mouth the English word without using the voice.
For example, we always mouth place names and the names of people whether they are finger spelt or signed. In fact we mouth most nouns as we sign them but we don’t usually sign verbs.
Some signs are not always signed because their meaning is clear e.g. YOU and ME
When we are signing our mouths must be clearly visible. Big moustaches, beards, scarves and eating while we sign make it difficult to understand mouth patterns!
One sign may have several different meanings so the word needs to be clearly mouthed. For example: toilet and live, nephew and niece, number and date.
Also, many signs use just the first letter of the word. So, some letters of the alphabet can have several meaning. Mouth patterns are needed to make the meaning clear.