Have You Heard My Coat Story?

    Anybody that visits Dogwood Ceramic Supply's showroom on a regular basis will often hear the question "Have you heard my coat story" being directed towards a customer.

What is a Coat?

What is a COAT?

    Hint:    Both are coats.  In simple terms a coat is a covering.  Depending upon the usage (or the weather) the idea of a coat may mean different things to different people.

    And now you have heard my COAT Story.

    So what is important about glaze COATS?

    Color manufacturers will direct their customers to apply 2, 3, 4 even 5 "FLOWING COATS" of a product, usually a glaze or opaque underglaze, to a bisque or greenware item being decorated.

    Drum roll please.....

What is a FLOWING COAT?

    In general terms a COAT is a covering, so a FLOWING COAT would be considered a flowing covering of glaze.  What really complicates matters (much like the problem between windbreakers and parkas) is that one glaze manufacturer's idea of a FLOWING COAT may be totally different than another manufacturer's idea of a FLOWING COAT.

    This FLOWING COAT concept is important, because the most common errors that we see at Dogwood Ceramic Supply are glaze application errors.  Actually the #1 error of 1988, 1989, 1990 and every year since has been excessive application of color products.  Yep, customers are wasting color products and the results are not always very pretty.

    Let's evaluate a classic glaze, such as Spectrum's 1140 Textured Kiwi.  Your Textured Kiwi has a serious case of the "glaze blisters", vertical surfaces, flat surfaces, textured ware, smooth ware, brown clays, white clays, hotter fired bisque, cooler fired bisque, soaks and holds and firing one or two cones cooler ... it don't matter what you do the glaze always blisters.  Well, at this point we can pretty much guarantee that too much glaze is being applied.  But you exclaim "I am applying three coats just like the bottle says".

    Yes, you may be applying three flowing coats, but if you haven't figured it out by now, your "flowing coats" are different than Spectrum's idea of a "flowing coat".  Sure, sure, you can never use Textured Kiwi again, or change glaze brands, or swear off of brushing glazes, or even stand on your head and use your left hand to apply the glaze.... but guess what..... eventually you are going to have the same problem with another glaze.

    Oh My Gosh, what should anybody do?

    At this point too many academic types will give you a lecture about the angle of your brush, the viscosity of the glaze, ambient room temperature, micro-calibration of your kiln, the density of the bisque, the firing rate of your kiln or even the phase of the moon.

    Dogwood Ceramic Supply has a simpler suggestion...

CHANGE THE NUMBER OF COATS YOU APPLY

    Hey, who said you can't change the number of coats you apply?  We can't remember anybody ever saying the number of coats was considered an absolute number.  Gosh darn, the manufacturers can't even agree on the definition of a "Flowing Coat", so who is to say that your idea of a "Flowing Coat" is not correct?  And if your idea of a "Flowing Coat" is correct, then the manufacturer's directions of three "Flowing Coats" must be wrong.

    Yep, changing the number of coats you apply is pretty simple.  A lot simpler than a discussion about the angle of your glaze brush or the phase of the moon.

   How do you know that you are applying the correct amount of glaze?  Test Vases.  Heard of test tiles?  Well Test Vases are similar to test tiles in purpose, but the vertical surface of the vase is quicker to demonstrate under or over application of glazes.  So throw, buy, shape, cast or whatever a handful of relatively small vases and bisque fire to your normal temperature (Cone).  Keep the vases around and whenever you need to check your glaze application use a couple of your vases.  Apply a different number of "Flowing Coats" to each vase.  If your problem is over-application then you may want to apply 2 Coats to one vase, 2 Full Coats plus one Half Coat to another vase and 3 Coats to a third vase.  In a few extreme cases you may even want to try less than 2 Coats.  We are willing to bet that one of the lighter/lightly glaze applied vases will achieve glaze perfection for you.

   What is the "HALF COAT" previously mentioned?  No, it is not a windbreaker with only one sleeve.  A Half Coat is an application of thinned color.  The Half Coat is ALWAYS applied as the first coat, allowed to dry and then normal, full strength coats are applied on top of the Half Coat.  A Half Coat is also sometimes known as a Glaze Scrub Coat.  Glaze Scrub Coats are commonly used with glazes, such as Duncan IN 1653 Downright White, which have a tendency to pull or shiver from areas when the product is not applied perfectly even.  Glaze Scrub Coats will be applied with a slightly stiffer brush and intentionally scrubbed across the surface of the item to be decorated causing some of the glaze material to travel deep into the pores of the ware and tacking down the glaze to keep it from wanting to shift during the firing.  Glaze Scrub Coats are also common on highly detailed wares to bind the glaze into the fine details.

    For our purposes the Half Coat is just a thin layer of color that is added to, or in place of, full strength Flowing Coats.  The Half Coat is best achieved by diluting a small quantity of the glaze material in a disposable paper cup with equal quantity of water.  Tap water is fine for 99% of our customers, but if your water is high in dissolved minerals, especially iron, then distilled water should be used.  Any excess quantity of this diluted glaze should be disposed, not returned to full strength product reservoir.

    The use of Half Coats has allowed many customers to achieve glaze perfection.

    Perfect glaze is achieved when the surface of the glaze is free of defects.  Even when there appears no large defects, excessive application of glaze will often result in extremely fine bubbles in the surface of the glaze.  In the automotive industry, a car with a bad paint job with similar fine bubbles will be said to suffering from an "orange peel" paint job.  Evaluate your glazed items from various angles with the light coming from different directions.  Those fine bubbles are easy to spot once you know what to look for.  Excessive application of glaze will also obscure the fine details in the ware, or in the case of clear glazes will show as yellowing when the glaze pools near details or can even obscure underglaze decoration.  Extremely excessive application will result in large bubbles, often called "glaze volcanoes".  Under application of the glaze will result in mottled, splotchy or uneven color on the smooth areas and rough surface on the detailed areas as the glaze is usually insufficient on the sharp edges of the details.

    Still got problems with your COATS?  How about changing your brush?  Yes, brushes can make a difference.  Actually worn out brushes are usually the problem.  Remember, clay is abrasive and bisque is especially abrasive!  When you apply glaze with a brush the bisque acts much like sand paper, slowing grinding away the ends of the bristles.  Natural hair brushes are more resilient that synthetics, even so the life expectancy of a good glaze brush may only be a few dozen projects.

    (Yea, right, you just want to sell me more brushes.  Ok, maybe we do want to sell you more brushes.  But take a look at your OLD brush... bristles worn away, other bristles suffering from a serious case of the split ends, the shape of the brush has been so modified that some bristles are now shorter than others or the brush has the appearance of an angled shader.  Yep, it is time for a new brush.)

    Besides the worn-out brush issue, Dogwood Ceramic Supply has found that some customers will really benefit from changing the type (style) of glaze brush they are currently using.  We sell a variety of glaze brushes, sometimes switching to (or from) a stiffer or softer glaze brush will make a world of difference.  And like the Coat Story, there is no right or wrong type of glaze brush.

    Need some more help with your COATS?  We have a couple more tricks up our sleeve, so visit the Dogwood Ceramic Supply showroom and bring a COAT 'cause it might be cold outside.

© 2008-2012, Dogwood Ceramic Supply

12590 Dedeaux Road
Gulfport Mississippi, 39503
Telephone (228) 831-4848        Fax (228) 831-3111

Showroom Business Hours:

Monday, Tuesday, Friday and Saturday 10AM to 5PM
Thursday 1PM to 6PM

Closed Wednesday and Sunday

In general terms a coat is a covering, so a flowing coat would be considered a flowing covering of glaze. What really complicates matters (much like the problem between windbreakers and parkas) is that one glaze manufacturer's idea of a flowing coat may be totally different than another manufacturer's idea of a flowing coat.