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.
	D.	Contamination of coating.	D.	Keep containers sealed.
	E.	Minute blistering.	E.	See Blister.
	F.	Underfired	F.	Increase heat, slow down firing process. Consult supplier for coating with proper firing range.
Cracking	A.	Coating film too heavy.	A.	Apply thinner coating.
	B.	Shrinkage of coating film due to fine particle size of solids.	B.	Apply thinner coating. Consult supplier.
	C.	Moisture in coating material.	C.	Consult supplier. Keep containers sealed.
	D.	Condensation on substrate.	D.	Store substrate in screening and/or firing area 24 hours prior to processing.
Craters	A.	Water droplets from air lines; sprinklers; ; leaking pipes; condensation from ventilators, air conditioners, water lines, coolers, beverages.	A.	Clean air lines, use filters, wrap pipes, keep sources of water away from immediate work area.
Also:
Dimples
	B.	Oil droplets from air lines, lubricants, thinners, hand cleaners.	B.	Clean air lines, use filters. Avoid excess lubricants on equipment. Thin the coating materials away from usage areas. Use hand cleaners away from machines, conveyors, racks, screens, open containers of coating materials.
	C.	Solvent droplets from thinners, extenders, hand cleaning, wash-up.	C.	Remove decorated parts from areas where solvent is being used.
Crawling	A.	Poor wetting of the substrate.	A.	Add wetting agents. Consult supplier.
Also:
Creeping,
Fish eyes,
Pull-back
	B.	Contaminated supbstrate.	B.	Clean substrate.
	C.	Presence of silicone lubricant.	C.	Clean substrate. May require heating the substrate to 800°F if cleaning alone does not remove contamination.
Crazing	A.	Improper match of coefficient of expansion of the coating to the substrate.	A.	Consult supplier.
Creeping		See Crawling.
Crizzle	A.	Moisture in the undercoat.	A.	Avoid temperature extremes before firing. Contact supplier if condition persists.
Dark reaction	A.	Coated material has exceeded shelf life.	A.	Replace with new material.
(U.V. Ink)
	B.	Coating material was stored at elevated temperature.	B.	Change storage area to cooler (-room temp.) location.
	C.	Formulation unstable.	C.	Consult supplier.
Delamination	A.	Contaminated substrate.	A.	Clean or replace substrate.
Also:
Ragged lines,
Sawtooth
	B.	Overcured base coat.	B.	Reduce cure time.
	C.	Gross mismatch in expansion between layers.	C.	Consult supplier.
Digs	A.	Impact with a foreign object.	A.	Change storage location to a safer, protected area. Instruction on safe handling. Use a cover plate during storage.
Dimples		See Craters.
Distorted image	A.	Too much squeegee pressure.	A.	Reduce squeegee pressure.
	B.	Insufficient screen tension.	B.	Replace screen.
	C.	Weak screen frame structure.	C.	Obtain more rigid frames.
	D.	Distorted artwork.	D.	Obtain new corrected artwork.
	E.	Too much off-contact.	E.	Reduce off-contact. Replace screen.
Drying in	A.	Coating dries too fast.	A.	Use slower drying coating. Consult supplier. Use flood coat immediately after printing.
	B.	Operation is too slow.	B.	Speed up the process.
	C.	Too much air flow over the screen.	C.	Redirect air flow from fans or other sources.
Dull finish	A.	Underfired.	A.	Elevate temperature. Reduce speed through furnace. Use lower maturing colors.
	B.	Blistered.	B.	See Blister.
	C.	Surface contaminated by inorganic dust.	C.	Keep clean (dust covers).
	D.	Devitrification - crystallization.	D.	Reduce heat, increase speed through furnace, use higher maturing colors.
Film thickness variation	A.	Improperly tensioned screen fabric.	A.	Tighten or replace screen.
Fish eyes	A.	Waterspots on substrate when using oil base coating.	A.	Clean substrate.
Also:
Crawling.
	B.	Oil spots on substrate when using water base coating.	B.	Clean substrate.
	C.	Silicone lubricants and additives.	C.	Avoid the use of silicone containing lubricants where possible. Do not over lubricate. Be very careful and accurate when using silicone containing additives.
	D.	Foreign materials on substrate.	D.	Clean substrate.
	E.	Improper mix of coating materials.	E.	Improve mixing procedures.
Flaking	A.	Coating film too thick.	A.	Reduce film thickness with finer screen, thinner screen emulsion, thinner coating viscosity, or harder squeegee.
	B.	Damage to coating film from impact, handling or stacking.	B.	Handle with care.
Ghost		See Smearing.