ASTM_C_1545_-_02_2016.pdf

Designation:C154502(Reapproved 2016)Practice forDispersing Pigments and Other Materials into Water-BasedSuspensions with a High Intensity Mixer1This standard is issued under the fixed designation C1545;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 In preparing ceramic glazes and slurries for use,it isoften necessary to add pigments to develop a desired firedcolor,to incorporate viscosity control agents for developing,orproviding to develop the desired thickness of the glaze on theware,to add materials which stabilize the suspension,controlbacterial growth,and develop the desired hardness of the glazeon the ware to allow moving and handling before firing.Whileit is convenient to add these materials to the glaze or slurry inthe dry form,it is often possible to use slurries where thesematerials are dispersed in a slurry and the slurry then added tothe liquid glaze.Regardless of the state of the additions(dry orslurry),the dispersion can be done efficiently and effectively bythe use of a high intensity mixer(sometimes referred to as adissolver)and the procedure used is described here.1.2 The values stated in SI units are to be regarded as thestandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C242 Terminology of Ceramic Whitewares and RelatedProducts3.Terminology3.1 Standard terminology for ceramic whitewares and re-lated products is given in Terminology C242.4.Significance and Use4.1 The traditional method of preparing glazes and slurrieshas been to add stains(pigments),stabilizers,viscosity controlagents,bactericides,and so forth,to the pebble mill batchalong with normal batch materials such as clay,frit,quartz,feldspar,whiting(calcium carbonate),zinc oxide,opacifier,and so forth.This method had the disadvantage of overgrinding some of the materials of the batch and under grindingother materials.While part of the disadvantage could bealleviated by double or triple batching(where the pebble millwas stopped at one or two points in the cycle and one or morematerials added),the practice was labor intensive and notalways well controlled.Another disadvantage of the traditionalmethod was that it was necessary to thoroughly wash out themill between batches of different colors.An obviousadvantage,however,was that small components of the batch(such as pigments)were thoroughly dispersed in the batch andeven today it is necessary to use this procedure when smallquantities of strongly colored pigments are to be used.4.2 With the advent of high speed intensive mixers using arotating shaft-mounted impeller,it is now the usual practice toadd pigments,conditioners,and so forth,to the batch from thepebble mill and accomplish the same uniform dispersion aswould be the case if the pigments were milled in rather than“stirred”in.In addition,the pigments tend to yield a strongercolor in the glaze because they have not been over ground inthe pebble mill.It is not uncommon to make a reduction in theamount of pigment needed to develop the desired color whenthe pigment is stirred in rather than milled in.An even greaterbenefit is using the“stirred in”technique is that a single largebatch of a base glaze(for example,clear)can be made bymilling,and individual colors developed by stirring appropriatepigments and conditioners into small amounts of the baseglaze.In this way,a large pebble mill can be dedicated to clearbase glaze and cleaning the mill between batches is not needed.Glaze stains frequently are treated with proprietary materialswhich assist in dispersing the stain into the glaze.5.Apparatus5.1 There are two types of high intensitymixers(dissolvers),those designed for laboratory use,where capacityis approximately 10 to 15 litres of liquid,and those designed1This practice is under the jurisdiction of Committee C21 on Ceramic White-wares and Related Products and is the direct responsibility of Subcommittee C21.03on Methods for Whitewares and Environmental Concerns.Current edition approved Nov.1,2016.Published November 2016.Originallyapproved in 2002.Last previous edition approved in 2012 as C1545 02(2012).DOI:10.1520/C1545-02R16.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 for production use,where capacity ca