I have always told my students that even if you dip your ceramic piece in pure gold it is not worth two cents if you do not clean it properly to begin with. Good cleaning is the difference between ceramics as a craft and ceramics as an art. Even a beginner can create a work of art.
Spending a little extra time to remove all traces of seams and re-incising details will always pay off in the long run. There are lots of little tricks of the trade that will help speed up the process, but you should never sacrifice quality for speed. Giving that extra bit of attention to your piece can raise its value and garner you a reputation that will keep your customers happy and returning.
There has been a lot of information written about the ‘how to’s’ in cleaning ceramic greenware, but my wonderful teacher showed me a method that I have passed on for almost 50 years that makes the process easy and quite fast. As you become experienced, you will be amazed at just how fast you can whip through a table full of greenware.
If you have gone out and purchased a bunch of cleaning tools, you have really wasted your money.
* All you need is a sponge – a silk or natural sponge is best;
* a cleaning tool – Kemper has a double ended tool with a curved, spoon shaped knife on one end and a sharp pointed knife on the other end;
* a sanding block – this is a block of sponge with sanding grit on all sides;
* a sanding stick – smaller version of the sanding block
* a round, stiff bristled brush - #6 or #8 (or both, depending upon the size of your item);
* and clean water.
All the other bells n whistles will work, but not any better than the things I just listed.
PLEASE NOTE: Cleaning Porcelain greenware is a different process. This article pertains to cleaning low-fire ceramic earthenware, stone ware and other similar clays.
Always remember, during the cleaning process, it is important to support the weight of the item. Never pick up greenware from the top or the opening and hold it firmly, but not so firm as to break it. Pretend you are working with half an eggshell, you don’t want to squeeze too hard.
Step one: Cover your work area with disposable paper such as newspaper. Make sure you have assembled all your tools and a bowl of water.
Step two: Using the tip of the curved, spoon shaped end of your clean-up tool, make fairly deep cross hatch cuts every where the seam crosses any detail. You will cut across the seam, following the detail line and creating a cut/groove that if you were able to view it as a cross cut it would look like a “V”. Follow the seam line, cutting through it where ever there are details or turns. You want to make cuts, not scratches.
Step three: Using the same spoon end, scrape way the seam lines scraping at an angle across the seam with short strokes, not long strokes following the line. Note, your knife will automatically stop when it comes to one of your previous cuts. Use the knife end of the tool in areas that are more difficult to access. Do not create gouges in the seam, but gently scrape away enough that you don’t see the ridge of the seam line. You may use a sanding stick for smaller areas and a sanding block for larger areas instead of the knife.
Step four: Use the sanding block in a circular motion for plain items and flat areas like the bottoms of your pieces. Use the corners or a sanding stick to reach into those crevices and turns
Step five: Check your item for any other blemishes and remove or repair them as needed. Make sure the bottom of your item is level, so it will sit properly. If you need to level your item, use a sanding screen.
Step six: With your dry round brush, brush away any dust on your item.
Step seven: Dip the round brush in water (selecting which ever size best suits the size of your item) and blot the brush on the sponge to remove excess. Brush out all of your cuts with a stroke that follows the cut. Rinse the brush frequently, always remembering to blot out excess. You do not want to over saturate the ware. You want to use enough water and pressure to smooth out the cuts so they blend in with the detail lines and are somewhat softened and rounded. You do not want to brush away the details, but rather enhance them. Touch up stubborn cuts with cleaning tool if needed.
Step eight: After opening up all the cuts, use the same brushing process to smooth out all the seam lines. Scrub slightly, just enough to move the surface of the clay if needed, but not so much as to wash away the details. Remember to rinse the brush frequently and go over any areas that show brush strokes with a lighter pressure. DO NOT over saturate your ware.
Step nine: Wet your sponge and wring out all the excess. You want your sponge damp, not wet. Wipe down your entire piece carefully. Remove any remaining brush marks and blemishes. Do not polish the surface. Too much water and too much rubbing can create ‘hot spots’ that will not readily accept paint. It can seal the ‘pores’ and repel paints and other products.
Step ten: Let your item dry, walk away so when you come back to examine it you will have fresh eyes. Check for any blemishes or missed spots and correct them. When satisfied that your cleaning job is done and your ware is perfect, you may paint with underglazes or fire it to your desired cone.