Air Bag Tightness
The bag should be checked for air tightness. To do this, remove all the pipes from their stocks, except the blow-piece. Stop firmly each remaining stock with a suitable size rubber stopper or wine corks (without any leaks).
Inflate the bag by mouth (not a high-pressure pump) to as high a pressure as possible, and beware of any of the stoppers popping say into your eye, hence “stopped firmly” mentioned before. The bag should be “as tight as a drum” and not lose any appreciable air over the next 20 to 30 seconds as a guide. If the bag becomes slack too soon, then check that all stocks are bound firmly by trying to turn them with a strong twisting action. If loose, then rebind very firmly with good strong twine if a hide bag, or if clamped tighten or re-adjust. The next step would be to see if the hide on a hide bag appears to be dry internally and needs a suitable amount of dressing to become airtight. Check also the seams for signs of leaks, which dressing can often prevent. If the hide appears to be old and stiff etc., renew the bag. Patented bag dressing should have a directions label. Test as before, which also helps to pressurize dressing through any tiny seam leakage. Clean all stocks thoroughly with a suitable dowel and moist lined cloth or similar cloth, then with a dry cloth.