(2) Make cores for casting so that they are filled with air bubbles and an imperfect cast results.
(3) See that the core in a mold is not properly supported, so that the core gives way or the casting is spoiled because of the incorrect position of the core.
(4) In tempering steel or iron, apply too much heat, so that the resulting bars and ingots are of poor quality.
(b) Other Metals
No suggestions available.
(4) Production: Mining and Mineral Extraction
(a) Coal
(1) A slight blow against your Davy oil lamp will extinguish it, and to light it again you will have to find a place where there is no fire damp. Take a long time looking for the place.
(2) Blacksmiths who make pneumatic picks should not harden them properly, so that they will quickly grow dull.
(3) You can easily put your pneumatic pick out of order. Pour a small amount of water through the oil lever and your pick will stop working. Coal dust and improper lubrication will also put it out of order.