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Puretch Troubleshooting Tips

Problem 1: Film coming off when removing top mylar for development

Cause & Trearment: Moisture is not being removed from film after water lamination. Make sure film is squeegeed evenly and firmly. A climate controlled room is strongly recommended. Use a blown heater or hairdryer to remove moisture from film and improve adhesion. If you are not able to get plate surface up to 180F then dry the plate for much longer time than recommended. Humidity in shop may also be too high, relative humidity should be 60% or lower. Plates can be dried overnight without heat in proper humidity. It is a good idea to laminate several plates at one time and dry overnight for exposure the next day as this saves time and energy. A digital hygrometer is highly recommeded to monitor relative humidity in the shop.

Problem 2: White, cloudy spots forming under film after lamination

Cause & Trearment: Usual cause is un-pure water or excess moisture not being removed, see Problem 1. Use distilled water for lamination. If using paper towels on clean copper, Bounty is preferred to other brands because it is chemically free. Powdered cleansers and contaminants not rinsed fully are also possibly to blame, check humidity first. If problem persists and humidity has been ruled out, eliminate powdered clenser and switch to a good metal polish, followed by a high strength degreaser such as Right Stuff or TSP, Tri Sodium Phosphate. Do not use cleaners with orange oil or D-limonene. DO NOT SAND YOUR PLATES. Sanding plates makes microscopic valleys and ridges that can trap cleaners and prevent Puretch from adhering because it may not let Puretch reach the valleys. This method only works for thicker films and is not recommended for Puretch. Sanding plates creates too much plate tone and can also negatively affect resolution fidelity because the surface is roughened and may refract light during exposure.

Problem 3: Not able to etch small dots in hilghights

Cause & Trearment: Ensure that dots are opaque. Exposure may be too long. Shorten exposure and use a Stouffer to determine correct exposure times. It may be necessary to expose at the #4 or 5. See this page and see Stouffer. Use very dillute ferric chloride and brush over plate right after developing. If the copper stays shiny in the details then develop a little bit longer. When the copper looks dull after the ferric it is developed. Do not increase strength of developer. Flourescents can cause dots to not develop, always use a point light; one clear bulb light source from one point. If you don't have a Stouffer then test a small piece of Puretch exposing it with your lightest gray swatch or thinnest lines, expose for varied times, develop and etch. Use the longest exposure that allows an etch of all the dots.

Problem 4: Film breaking down during development

Cause & Trearment: Exposure may be too short, use a Stouffer to determine correct exposure, do not adjust development time, always keep this standard and adjust exposure. If exposure has been ruled out then usually the film has not dried fullyafter laminating it to the plate with water. The mylar may remove properly but areas that should remain on the plate will swell during development and eventually come off. The film needs to be dried longer. See problem 1.

Problem 5: Plate not biting evenly, streaky or splotchy

Cause & Trearment: Plate may be overexposed. See Stouffer info above.
Since high resolution halftones require shorter etch times than line work, sometimes a small difference in etch time can be visibly apparent. Placing a dry plate in ferric can sometimes result in this. We highly recommend you briefly wet the plate surface with Puretch developer in a 'pre bath' followed with a quick rinse of both sides prior to placing in etch. It is important to rinse this before etching or it will begin to neutralize the ferric.
Use a feather to agitate the ferric into the entire surface immediately upon submersion.
Plate may not have been handled carefully after development, do not touch plate surface with fingers after drying.
Plate may be oxidizing before laminating the film. Laminate film immediately after cleaning plate.
Etch that day if possible to prevent oxidation of exposed copper. If the developed plate has sat around for a while before etching and become oxidized then brighten the copper in a mild salt, vinegar and water solution, rinse thoroughly and go straight into the ferric.
Sometimes a very thin layer of undeveloped scum will remain in areas that are to be etched. It is still possible to rub with developer and a soft brush to remove this prior to etching if the emulsion has not been hardened yet. Examine plate in regular incandescent light to make sure all traces of unwanted resist are gone before hardening the resist.
If using paper towels on clean copper, Bounty is preferred to other brands because it is chemically free.

Problem 6: Film not adhering at edges of plate

Cause & Trearment: Do not bevel plates before lamination. A slight burr from shear may cause an air pocket at edge, carefully knock this off with a scraper or file without over beveling. Clean back of plates around edges to keep grease, etc from creeping in at edges. Always trim film from front side of plate with very sharp blade. Do not prop plates on edge for drying, this can cause delamming at that edge, dry flat instead.

Problem 7: Small holes in film and etch

Cause & Trearment: Dust and dirt particles in lamination or exposing unit. Clean glass in contact frame on both sides with razor blade and glass cleaner. Always work in a clean, dust free lamination room. Use compressed air on plate prior to spray and lamination. Inspect plate and retouch pinholes with paint marker or asphaltum prior to etching.

Problem 8: Film is not exposing and developing like it was previously

Cause & Treatment: Film may be old or stored improperly. Puretch has a one year shelf life, check date of purchase. Store film in black bag in the box between 40 and 70F and between 30% and 70% humidity. The shelf life may be extended beyond a year if it is stored in the cooler temps within this range. If you do timed exposures and don't use a light integrator, your light source may have weakened. Do a Stouffer test to determine how film is responding and make necessary adjustments.

Puretch Info Puretch Halftone TutorialJennifer PagePrint Sites ofJennifer Page - OwnerGravure Pigment PaperPhotogravurePhotogravure PlatesCape Fear Press