I usually spray on glazes. Recently, I made some shapes much too complicated and restricted to get even an airbrush in position to spray. The only alternative I can see is brushing on glazes. However, my glaze brushing looks like a four-year-olds fingerpainting. Can someone explain how to get very nice smooth glaze application with a brush, or point me to an article that lays it out.
Brushing Glaze Smoothly
Posted 21 March 2015 - 02:16 AM
Posted 21 March 2015 - 02:29 AM
( ' x ' )
( u u ) . . . .
Posted 21 March 2015 - 03:00 AM
What cone are you using ? I find that higher temperature glazes are harder to brush, but discovered that adding a few drops of glycerine to the glaze helps.
Posted 21 March 2015 - 03:19 AM
Brushing over with a soft brush and finger sanding the dry glaze will smooth out the worst irregularities (if you can reach them!)
I've also added glycerin, which helps by slowing down the drying time. If you use this, I'd advise against tipping it back into your main bucket, as it tends to grow mould.
Posted 21 March 2015 - 11:50 AM
What do you mean that "the glaze has to be formulated for brushing"?
I'm firing at cone 6 oxidation
In the right brush, what parameters do you look for?
Is there any reason to believe that brushing additives do any better than glycerin. I've tried glycerin. It seems to help a bit, but I'm not impressed.
Has anyone tried V-gum or CMC to make the glaze more brushable?
Posted 21 March 2015 - 04:49 PM
Doc - I have these notes about CMC gum.
Powdered gum resists dispersion in water thus it is difficult to add it to an existing liquid batch. However if gum powder is mixed with other dry ingredients before adding them to the water it can be done (often 0.5-1.5%). A much more effective method is to boil water, add about 25-30 grams of powdered gum per litre and mix vigorously with a mechanical mixer. Normally this mixture is added during mixing to replace part of the water however I have found that for brushing it should be used to makeup the entire water complement. There is room to use 40 grams per liter if needed.
CAD 14/2/15 Neilstrick
Add 2 tablespoons CMC Gum to a gallon of water. Add 1/4 teaspoon copper carbonate as a preservative, otherwise bacteria will eat up much of the gum within a few days. It will not affect the color of the glaze. Let it sit overnight, then blend with a hand blender. When making your glaze, substitute the gum solution for about 1/3 of the water.
Posted 22 March 2015 - 10:56 PM
For brushes, it's more a personal choice. I like the soft bristled synthetic ones. Fan brushes in particular I found do a large area with little glaze waste and brush on smoothly. For smaller areas I like the cheap bamboo brushes.
- Mari likes this
Posted 22 March 2015 - 11:05 PM
wet the greenware before trying to brush anything on it. just dunk it in a bucket of water, it is surprising how little water it takes to make the piece not act like it has been in a desert for a week.
Posted 23 March 2015 - 08:36 AM
Oldlady, you mean bisqueware, right?
Commercial brushing glazes directions usually advise to brush each coat in opposite directions....but I have never done that and get good results anyway. Having done a lot of brushing, I've found that some glazes come out better than others. Some I need to be meticulous with, and others come out good now matter what I do. My best advice is don't try brushing a glaze that is too thick, thin it down with water, work quickly, and be sure to let each coat dry before applying the next one.
"Promoting the joy of handmade pottery"
Posted 23 March 2015 - 10:39 AM
Brushing on glaze does take practice. I brush all of my glazes and have great difficulty in teaching the technique in class. I use a four section Sumi brush and try to FLOW the glaze off of the brush instead of painting it on. By flow I mean never let the brush starve out and go dry. This means loading it up fully till it almost drips and immediately brushing it on the piece till the brush starts to run out of glaze. You need to go fast and keep a wet edge. you can be a little sloppy and come back and brush over the runs and drips later.
I am usually able to to keep the whole piece moist enough to cover it with a full coat before it dries. I can then FLOW another coat over the first and even out the rough spots. The key is to keep the brush totally saturated with glaze and go fast enough so that you keep a wet edge between brush strokes. The big mistake people make is brushing on too thin. That is why four coats are required to do the job. I never use more than one thick coat and a second touch up on the thin areas. I tell my students to put it on till it looks way to thick, and then it is about right.
I formulate my own glazes and keep them at about 60% solids. The thicker the better for brushing. I add 1% brushing medium (CMC + perservative) to help stick it to the pot and smooth the brushing. I weigh out the brushing medium and add just enough alcohol to get it so it is soluble, and swishes around on the bottom of the cup I use. I then quickly add this to the water I use for the glaze and wash the cup and water back and forth . I find this prevents the gum from clumping when the water hits it, and I don't need to use heat or high speed mixers to get it dispersed through the glaze mix.
I try to mask parts of a piece I don't want to glaze and just slop it on rather than use small brushes around tight areas. I use latex masking that pulls off and seldom require touch up around the masked areas.
As Cilia said, the glaze tends to level in firing, and if I have applied it heavy enough I don't get brush marks.
Posted 23 March 2015 - 07:10 PM
thanks for all useful suggestions. As I have been experimenting with them, it also seems helpful to flocculate the glaze with Epson salts or calcium nitrate.
Posted 23 March 2015 - 10:40 PM
thanks, doris, i fixed it with "edit". a late night after a long day...................
0 user(s) are reading this topic
0 members, 0 guests, 0 anonymous users