Enamel slip is a dry powder mixture that is suitable for applying to a metal surface. Slip is created by milling raw materials into powder in a ball mill that contains porcelain-grinding materials. The raw materials may include enamel frit (vitreous glass granules), water, clays, pigments and electrolytes.

What you must do

Dry milling and the addition of frit to wet milling operations can be noisy and create substantial quantities of dust. You may need to take measures to control noise and dust from your premises.

Air quality

Noise and vibration

Ball milling can produce liquid wastes in the form of mill room washings and cooling water.

You must not make any discharge to surface water or groundwater without consulting your environmental regulator. If you discharge without an authorisation, permit or consent from your environmental regulator you could be prosecuted and fined or imprisoned.

Preventing water pollution

You must not discharge trade effluent to a public sewer without trade effluent consent or a trade effluent agreement with your water and sewerage company or authority. If you discharge without a consent or agreement you could be prosecuted and fined or imprisoned.

Trade effluent - managing liquid wastes

You must comply with your duty of care responsibilities when dealing with waste.

Duty of care - your waste responsibilities

Controls have been introduced to limit the sulphur content of fuels. You must not use gas oil with a sulphur content exceeding 0.1% by mass.

You must not use heavy fuel oil with a sulphur content exceeding 1% by mass. This is particularly relevant if you have stocks of stand-by fuel that can remain unchanged for considerable periods of time. If you operate pre-1987 combustion plant you can apply for a Sulphur Content of Liquid Fuels Permit from your local council in Northern Ireland or SEPA in Scotland.

Good practice

  • Store empty packaging and collected dusts in sealed containers.
  • Locate milling operations away from your site boundaries to avoid causing a nuisance.
  • Limit milling to daylight hours. Any noise you make at night is more likely to be a nuisance than during the day.
  • Consider using pre-packaged and pre-weighed ingredients kits. This should lead to efficient use of materials.
  • In some areas, your water company or authority will have zero discharge limits for certain metals, eg cadmium, lead and nickel. If your effluent treatment system cannot achieve the required limits and your business is located in such an area, you should use tankers to take your water off-site for treatment.
  • Water that has been used for cooling can be reused in rinse baths and washing activities.
  • Provide accurate measuring vessels for slip ingredients.
  • Use funnels to add mixtures to the ball mill. This will reduce the risk of spillage.
  • Regularly investigate alternatives to enamels that contain hazardous metals such as cadmium and lead. Eliminating these substances from your waste can reduce your waste management costs.
  • Work with your waste contractor to find out if mill room washings should be handled as hazardous/special waste. If you change your colour ranges, reassess whether the waste needs to be handled as hazardous/special waste.
  • Segregate cadmium-bearing waste from general waste. This allows you to treat and recover or dispose of this waste separately. Consider using dedicated mills for enamels that contain cadmium.
  • To reduce waste, carefully estimate the amount of slip you require.
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