Walkers/Cesco Glazes
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BRUSH ON GLAZES FAQs
LIQUID GLAZE ( BRUSHING GLAZE)
Liquid glaze is prepared ready to use. However, as materials in some glazes tend to settle after standing, it is important to shake or agitate the container vigorously, then stir, before use. If after shaking and stirring the glaze it is still too thick to load a glaze brush easily then it may be necessary to add a little water.
PRIOR TO GLAZING
Bisque fire the ware to its recommended temperature (minimum 1000°C). Sponge bisque with a damp sponge to remove any dust which may have collected. On narrow necked pieces where a sponge cannot work, use a clean damp brush. Do not eat, drink or smoke whilst handing your work as any grease transferred to the bisque will resist glaze. Although it may appear to cover grease spots when applied, glaze may crawl away when fired.
APPLICATION OF BRUSHING GLAZE
Once the container of liquid glaze has been shaken and stirred, load your glaze brush by immersing the hair up to the ferrule. Remove the glaze from one side of the brush and apply the fully loaded side to the bisque. As an approximate guide, a fully loaded brush will go about 80 mm before it should be re-loaded. Apply one even coat, let the “wet” look disappear, then apply a second coat in the opposite direction. When the second coat has lost its “wet” look, apply a third coat in the same direction as the first.
GLAZING THE INSIDE OF NARROW NECKED PIECES
This process should be done before application of the exterior colour. If using brush-on glazes exclusively, it will be necessary to thin some down for rolling the inside of any ware that cannot be reached by a brush. Do not thin down a whole jar unless it is to be used only for rolling. The addition of water will vary according to the original consistency, however as a rough guide, use three parts liquid to one part water. Replace lid and shake thoroughly. Pour thinned glaze into ware and roll piece around so the glaze can cover all internal surfaces. Pour out slowly whilst still rolling so the glaze can cover the internal lip of the ware. Leave upside down for five minutes to drain.
POWDERED GLAZE FAQs
Setting up a glaze from powder for Dipping, Spraying and Brushing
MIXING
For dipping or spraying
Wearing a suitable mask, sprinkle the glaze powder into a suitable container of water and stir thoroughly. Leave to settle overnight and pour off surplus water. Stir, sieve through an 80 mesh or finer sieve, then add water if necessary to achieve the desired consistency – a bit thicker than Full Cream Milk.
Mixing proportions start with:
Lead free glazes 1kg to 1000mL of water
Mid Fire & Stoneware glazes 1kg to 1150mL
Lead Bi Silicate Frit based glazes: 1kg to 810mL Water
TO REMOVE water: allow the glaze to settle and skim off clean water from the top
When ADDING water: add very cautiously, stirring well between additions
When some liquid glazes settle out, particularly over a long period of time, they sometimes set hard at the bottom of the container, making them difficult to re-mix. Others may settle during use and consequently demand thorough stirring or agitation during the dipping / spraying session. To correct this defect, a flocculant or ‘anti-set’ solution should be added a little at a time, (see Epsom Salts solution recipe below) stirring it in very well until the settling stops. Add carefully or the glaze will dry slowly on the ware and may cause ‘mud cracking’, ‘peeling off the biscuit’ and perhaps ‘crawling’ during firing. Glazes that have a high clay content, raw zinc oxide, magnesium carbonate, talc, etc., or have had excess dosing of ‘anti-set’ will have this defect. The cure is to add very cautiously, small quantities of a 10% solution of deflocculant – Soda Ash, Dispex or Sodium Silicate, stirring well, until normal drying and behaviour occurs.
APPLICATION
Use either a bucket or glaze wok or suitable spray gun. The type of glaze and the effect desired will indicate how the ware should be applied: transparent glazes should be thinner than opaque ones so dip once only. A rutile glaze may be dipped once or twice for varying colour effects. Walker Ceramics dipping glazes are delivered with a litre weight of 1500-1750 grams/litre (Specific Gravity (SG) of 1.5-1.75) depending on glaze composition. After application the glaze layer should be as thick as the diameter of a standard steel paper clip.
Litre Weight bottles are available to check your litre weights – Code HC80.
They are used to calculate accurate litre weights when mixing casting slips and dipping glazes. It is supplied with a simple conversion chart and also a method to test the accuracy of your scales. Litre weights can be checked on the supplied chart between 1380 and 1775 gm/L.
(To make Epsom Salts solution, mix 300 gm of Epsom Salts with 1 litre of hot water.)
It is highly recommended to use a Ford Cup or Viscosity Cup and aim for run-out time of 15 to 20 seconds.
After application the glaze layer should be as thick as the diameter of a standard steel paper clip.
For Brushing
Our Brushing Medium (Product Code CB180) and Painting Medium (Product Code CB160) have been developed so that they may be mixed with powdered glazes, stains etc. by simply stirring with a cake beater or paint stirrer and running the liquid through an 80 mesh sieve.
Suggested proportions are:
For lead-free glazes, approximately 1 litre of medium to 1 kg of powder plus water as required
For lead-bearing glazes, approximately 500-600 ml of medium to 1 kg of powder plus water as required