A detailed analysis is made in this problem solving guide for common problems faced in Gravure . A brief description is given of each dilemma along with the possible causes and remedies. If you still have more questions , please use our Enquiry section to ask our experts.

Abrasion ?  Adhesion ? Blocking ?
 Blushing ? Cobwebs ? Drying-in ?
Foaming ? Hazing or Toning ? Misprints ?
Mottled Print ?  Offset on Idler roller ? Poor Trapping ?
Pinholes ? Rub or Scuff ? Screening ?
Snowflakes ?  Static ? Streaks (hard) ?
Streaks (soft) ? Striation ?  

Abrasion ?

How Recognised: Cylinder Wear. Doctor blade wear.
CAUSE REMEDY
1.Poor dispersion 1.Re-grind ink
2.Specific pigment 2.Better pigment selection
3.Foreign matter 3.Filter ink
4.Soft chrome &/or copper 4.Remake cylinder
5.Excessive blade pressure 5.Reduce blade pressure
6.Corrosive ink 6.Consult ink maker

Adhesion ?

How recognised: Ink or varnish does not bind to each other
or to the substrate.
CAUSE REMEDY
1.Improper thinner used 1.Consult ink maker for proper thinner
2.Ink film not cured 2.Increase oven temperature
3.Improper ink used
 3.Consult ink maker

Blocking ?

How recognised: Ink adheres to back of web in rewind.
CAUSE REMEDY
1.Oven temperature too low 1.Check oven temperature
2.Thinner too slow for press speed 2.Use faster thinner
3.Trapped solvent 3.Use proper solvent balance. Check for surface drying
4.Web too hot when rewound 4.Reduce web temperature, use chill rolls
5.Excessive rewind pressure 5.Adjust web tension
6.Ink too soft 6.Consult ink maker

Blushing ?

How recognised: Printed ink has milky white looks.
CAUSE REMEDY
1.Improperly balanced thinner 1.Use balanced thinner
2.Humidity too high 2.Add slow prime solvent to thinner
3.Ink contaminated with water etc. 3.Discard ink - consult ink maker

Cobwebs ?

How recognised: Spider web-like build up on blade, impression roll cylinder & in oven.
CAUSE REMEDY
1.Ink starvation 1.Check pipes for ink blockage
2.Oven imbalance 2.Adjust air flow for a slight negative pressure
3.Oven air velocity too high 3.Reduce air flow in oven
4.Ink drying too fast 4.Slow reducer
5.Ink viscosity too high 5.Reduce viscosity

Drying-in ?

How recognised: Weak print. Colour intensity varies light to dark.
CAUSE REMEDY
1.Ink drying too fast 1.Scrub cylinder. Retard ink with slower reducer
2.Ink viscosity too high 2.Reduce viscosity
3.Ink not flowing out 3.Add clear extender
4.Air blowing on cylinder 4.Balance oven to achieve negative pressure
5.Poor wipe 5.Adjust doctor blade
6.Too much impression pressure 6.Adjust impression pressure
7.Ink contaminated 7.Replace with fresh ink

Foaming ?

How recognised: Air bubbles on surface of ink.
CAUSE REMEDY
1.Air entrapped in ink 1.Increase level of ink sump to prevent starvation
2.Slow pump and application flow
3.Use recommended defoamer

Hazing Scumming or Toning ?

How recognised: Very light and uneven transfer of ink in non-image area.
CAUSE REMEDY
1.Blade pressure too light-blade angle too flat 1.Increase blade pressure& sharpen blade angle
2.Poor knife edge on doctor blade 2.Replace blade-use pregroung lamella type blade
3.Ink dried on bottom of blade 3.Clean blade thoroughly or replace
4.Ink in non-image area not drying between blade and impression 4.Put air on cylinder-move blade away from nip. Put air on cylinder.
5.Rough cylinder 5.Hand polish or rechrome

Misprints (Voids) ?

How recognised: Solid areas show random areas in which ink is not transferring- Dots missing in process printing.
CAUSE REMEDY
1.Rough substrate 1.Increase impression
2.Partially plugged cylinder 2.Scrub etch with solvent & brass brush
3.Impression too light 3.Increase impression pressure
4.Ink starvation 4.Increase applicator flow
5.Damaged or pitted impression roll 5.Regrind or replace impression roll
6.Particles in ink 6.Filter ink through fine ink filter
7.Excessive foam 7.See remedies for foam

Mottled print ?

How recognised: Solid areas have variation in colour - grainy pattern.
CAUSE REMEDY
1.Viscosity too low 1.Increase viscosity with fresh ink
2.Pigment selection 2.Better pigment combination for colour match
3.Ink solids too low-ink not flowing 3.Add pigmented extender
4.Cylinder too deep or cylinder worn out 4.No immediate solution-replace cylinder

Offset on idler roller ?

How recognised: Printed image transferring to idle roll.
CAUSE REMEDY
1.Ink drying too slowly 1.Use faster thinner blend
2.Ink viscosity too high 2.Reduce viscosity
3.Oven temperature too low 3.Increase oven temperature and air velocity
4.Web temperature too high 4.Decrease oven temperature
5.Ink too soft 5.Consult ink maker for proper non-stick additives
6.Improper ink for substrate 6.Consult ink maker

Poor trapping ?

How recognised: Over printing ink not transferring over underlying inks pick back.
CAUSE REMEDY
1.First down ink not drying 1.Increase oven temperature and air velocity
2.Over printing ink redisolving 1st down ink picking back 2.Consult ink maker for lean reducer blend. Sandwich dissimilar inks
3.No pick back but ink not transferring to 1st down ink or not flowing 3.Use slower reducer mix reduce oven temperature of 1st down ink

Pin holes ?

How recognised: Small uncoloured holes in printed area.
CAUSE REMEDY
1.Rough or contaminated substrate 1.Increase impression pressure
2.Ink fails to flow out 2.Reduce viscosity - retard ink drying
3.Wrong ink for substrate 3.Consult ink maker for reformulation
4.Contaminated ink 4.Discard ink

Rub or scuff ?

How recognised: Dried ink rubs off printed product.
CAUSE REMEDY
1.Ink improperly dried 1.Increase oven temp., air velocity
2.Ink too soft 2.Use additives as recommended by ink maker
3.Insufficient wax or slip compound 3.Consult ink maker for wax additive

Screening ?

How recognised: Definite pattern of cell walls. Ink not flowing out.
CAUSE REMEDY
1.Ink viscosity too high 1.Reduce viscosity with recommended reducer
2.Ink drying in cells 2.Set oven for negative pressure to prevent air from blowing on cylinder
3.Improper ink for substrate 3.Consult ink maker for proper ink
4.Ink contaminated by foreign matter 4.Thoroughly flush system and start with fresh ink
5.Cylinder worn or cell walls too wide 5.Remake cylinder
6.Ink starvation 6.Increase ink flow, raise inner pan

Snowflakes ?

How recognised: Small random spots of unprinted area showing through a deposited ink missing dots in process.
CAUSE REMEDY
1.Ink drying too fast 1.Retard with slow reducer
2.Ink viscosity too high 2.Reduce viscosity
3.Rough stock 3.Increase impression
4.Cylinder plugged 4.Scrub cylinder thoroughly
5.Cylinder worn 5.Replace cylinder

Static ?

How recognised: Hair lines of ink starting from printed area occurring in random directions.
CAUSE REMEDY
1.Ink viscosity too low 1.Raise viscosity with fresh ink
2.Static in web 2.Use tinsel or static bar
3.Low moisture contact 3.Use steam generator to add moisture

Streaks(Hard) ?

How recognised: Distinct solid lines that occur in non-image area. This condition may be continious or intermittent. Lines move as blade oscillates.
CAUSE REMEDY
1.Abrasion or mars in surface of cylinder 1.Repolish cylinder
2.Worn or nicked doctor blade 2.Rehone or replace Doctor blade
3.Insoluble particles 3.Filter or replace with fresh ink

Streaks (Soft) ?

How recognised: Relatively wide streaks that show up in non- image area. Usually in non - systematic pattern.
CAUSE REMEDY
1.Soft particles behind doctor blade caused by contamination of ink 1.Clean blade well filter or replace ink. Thoroughly flush system
2.Excessive ink 2.See remedy for foam
3.Damaged doctor blade 3.Replace doctor blade
4.Worn cell walls on trailing edge design 4.Replace cylinder

Striation ?

How recognised: Wavy print pattern in direction of web travel.
CAUSE REMEDY
1.Ink viscosity too low 1.Raise viscosity
2.Vehicle solid too low 2.Add high solids extender
3.Ink contaminated 3.Replace ink
4.Too much impression 4.Reduce impression pressure
5.Worn cylinder, incorrect engraving 5.Replace cylinder
6.Ink not wetting substrate 6.Consult ink maker