PROBLEM		CAUSES		SOLUTIONS
Poor Adhesion	A.	Underfired.	A.	Increase temperature and/or slow down speed through firing cycle.
	B.	Contaminated substrate.	B.	Clean or prefire substrate.
Alligatoring	A.	Overprint is higher melting and/or more viscous during firing operation than undercoat.	A.	Obtain higher melting undercoat or lower melting overcoat from supplier.
Also: Tearing, Cracking
	B.	In UV systems this is often due to the wet film thickness being too thick.	B.	Reduce wet film thickness.
Backlap	A.	Too much coating on the screen.	A.	Reduce volume of coating material.
Also:
Backlash
Belt marks		See Chain marks.
Blister	A.	Moisture	A.
		(1) Condensation caused by substrate being brought into warm room after being stored in cool area.		(1) Bring substrate into printing and/or firing area 24 hours prior to processing.
		(2) Condensation under print caused by screening on cold substrate.		(2) Same as A (1).
		(3) Moisture in the color itself caused either by leaving containers open for excessive periods of time or moisture in the powder prior to being mixed with oil.		(3) Keep container tightly sealed when not in use. Consult supplier if problem persists.
	B.	Carbonaceous Materials	B.
		(1) Resins or other ingredients in the oil (or additives) that leave a residue (ash) upon firing. Usually gives the color a grayish cast.		(1) Keep records of additives and quantities. Consult supplier if problem persists.
		(2) Excessive furnace heat combined with low melting ceramic coating which causes the surface film of the enamel to fuse before the organic materials (oils, thickeners, etc.) are completely burned out.		(2) Preheat to 800F (427C) for 4 to 6 minutes. May need to change vehicle (medium) or use higher firing ceramic. Lower temperature a entrance of furnace. Slow firing cycle.
		(3) Dirty substrate.		(3) Clean. There is no substitute for a clean substrate.
		(4) Mixing incompatible materials.		(4) Be sure you know what you are mixing. When in question, ask!
		(5) Contamination, either organic or inorganic, usually covered, causing localized blisters but in sufficient quantity, can be dispersed throughout the coating.		(5) Same as A (3). Keep containers covered.
		(6) Coating too heavy.		(6) Add thinner or extender.
Blocking	A.	Coating material not dry.	A.	Improve drying process.
	B.	Substrate stacked prior to firing while still too warm.	B.	Add more cooling before stacking.
Bloom	A.	On glass surface, a result of moisture and/or atmospheric attack.	A.	Keep glass dry; fabricate as soon as possible. There is no method currently in use for removing the stain.
	B.	On silver stains: overfired.	B.	Reduce firing temperature and/or increase speed through firing cycle.
Blur		See Smear.
Breakage	A.	Improper heat treating.	A.	Adjust heat-cooling cycle.
	B.	Damaged glass surfaces or edges.	B.	Improve handling procedures.
	C.	Improper match of coefficient of expansion of the coating to the substrate.	C.	Consult supplier.
Chain marks	A.	Excessive heat during firing cycle.	A.	Lower the temperature.
	B.	Firing cycle too slow.	B.	Speed up the cycle.
	C.	Coating material too high maturing for substrate and cycle.	C.	Consult supplier.
Checking		See Cracking.
Clogging		See Pinholes D. and N..
Coating too heavy	A.	Coating too viscous.	A.	Add thinner and/or extender.
	B.	Screen mesh too coarse.	B.	Use finer mesh screen, monofilament fabric.
	C.	More pigment (and cost) than necessary.	C.	Consult supplier.
	D.	Dull squeegee.	D.	Sharpen squeegee.
	E.	Insufficient squeegee pressure.	E.	Adjust downward pressure.
Coating too thin	A.	Excessive thinning of coating material.	A.	Reduce amount of thinner used. Change to more effective thinner.
	B.	Screen mesh too fine.	B.	Use coarser mesh monofilament or stainless steel fabric and dull squeegee.
	C.	Insufficient pigment mix	C.	Unlikely, but perhaps can be increased if all else fails. Consult supplier.
Color variation	A.	Too much heat for coating being used.	A.	Reduce heat or speed up firing process. Consult supplier for coating with proper firing range.
	B.	Unstable pigments.	B.	Consult supplier.
	C.	Contamination of substrate.	C.	Clean substrate.