Water Soluble Ink for Waterless Lithography and
Nik Semenoff, February, 2003
History of development
Oil based inks have served printmakers well over the centuries, but today's climate for safer workshops has put a cloud over their continued use because of the hydrocarbon solvents needed for cleanup. After developing my waterless lithography process and it's reliance on less dangerous chemicals, my hope was that some day a suitable water-soluble ink can be found to eliminate hydrocarbon solvents from the studio. In 1996, I started to do some research into modifying existing oil based ink with emulsified additives and produced encouraging results. The lack of some necessary water reducible resins made my research difficult, as these only seem to be available to major manufactures in large quantity. Since my goal has always been to use materials available to the artists in their community, I looked at alternative materials.
In 1998, I became aware of Green Drop Ink that relied on binders using the water reducible resins that made ink water-soluble until drying. Since companies focusing on ink manufacturing were better positioned to do research and get proper materials, it was my hope that this group would be able to supply the printmaking community a product we so sorely need. I encourage the company to work towards a product acceptable to printmakers, giving them feedback from the samples they sent me. While the ink was not perfect in my opinion, it had some desirable qualities. The greatest problem I had with the ink was the speed of drying on the slab and its greater tendency to tint. Printmakers have rejected commercial oil based ink made for offset presses because of the drier added to the product. We need ink that will keep a constant viscosity on the slab during the printing session and can be easily modified to take into account the temperature of the studio. After much frustration, I fell back on my past research and tried mixing Green Drop ink into the Van Son Rubberbased Plus ink that I have found best for waterless printing. To my delight, I found the modified ink printed better that either ink alone and still cleaned up with soapy water from plate, slab and roller. I communicated this discovery to the Green Drop Ink company, urging them to produce a modified form of ink to fill the printmakers’ needs. They chose to reject my suggestions, and closed all communications between us.
Theory behind modifying inks
While it would be desirable that plain water alone could be used for cleanup, this requires binders to prevent fast drying on the slab - a characteristic of water based ink. With the available water reducible resins, this meant that the characteristic of ink is much different to oil inks. My approach is to use oil based litho ink and add water-based components that will emulsify into the former. In my research I found many ordinary products that could be used by using resins, retarders, and emulsifiers. Of the many materials that work, one should use those that will have a drying component or evaporate from the ink film within a few days. Because of the viscosity of common oil ink used by printmakers, emulsification and mixing of another viscous substance with it is easy to accomplish. I have found there is no need to use a muller - an ordinary ink knife will do just fine.
By including common oil based ink, we have ink that stays at the same consistency on the slab during long editioning and we retain the desirable quality of having prints that are completely waterproof on drying. Because of the oil content, we have to use detergents at cleanup time, but considering the advantages of not using hydrocarbons, this is a small sacrifice.
Types of materials used in modifiers in my early research
I have found that it takes basically two to three separate types of compounds to produce a good printing ink from commercial oil ink. The most important is the binder, which must be water soluble to start. It should not be a fast drying material, as this would destroy the quality of good ink for hand printing. If only a fast drying binder can be found, then some form of retarder must be added. Some materials such as glycols can fill the need of both an emulsifier and retarder, but others may be needed. By adding oils or resins, which are less viscous, the ink will become too loose to print well. Some form of body additive is needed to bring the ink back to a stiffer state.
Resins and oils
For today's safety conscious society, resin manufacturers have been developing a number of water reducible materials. They have successfully chemically modified oils and resins in such a way that they can be diluted with water, making them completely dissolvable in it. Amongst the products that would be usable are alkyds, polyester, urethane and the seed oils such as linseed. These products are slowly being introduced into the market place in consumer paints and varnishes, as well as more demanding coating products for industry. Since artists are aware of acrylic emulsions, they must understand that these are different than water reducible products. The common acrylic paints that artists use are called dispersants, which means the molecules of acrylic are separated by water and emulsifiers. As the water evaporates, the short chains of acrylic molecules are allowed to come in contact and join together to form long chains. After drying, dispersant films become completely waterproof. For that reason you can wash your new acrylic painting with soap and water without damage. Dispersants are recognized by the milky look of the emulsion.
Water reducible materials are truly miscible in water as each molecule is affected by it. Depending on the formulation, some of these can be made completely water soluble - or less affected by aqueous solutions. These are the common resins, such as alkyd, polyester, acrylic and urethane. Also available are modified vegetable oils such as linseed, soya and others. All water reducible products tend to be clear or only slightly milky.
There are times you will need to slow the drying of the ink on the slab, to allow you to complete your printing session with the same viscosity of ink. Ethylene and propylene glycols are very good to use, as they will evaporate from the printed image over a period of time. Since they may be difficult to find in a pure state, other commercial products could be brought into use. A very readily available and good retarder is Golden Acrylic Retarder, sold for painting in acrylic. While there will be other compounds present, ethylene or propylene glycol would likely be the main ingredient. Because ethylene glycol is more toxic than propylene material, it would be advisable if you can find a source for propylene glycol. While common antifreeze for cars is mostly ethylene glycol, there are other compounds such as oil to lubricate the water pump, probably making it a poor choice as a substitute.
One of the best and least expensive retarder is available in common automotive brake fluid. It is made up of nearly 100% polyalkalene glycol ethers that are completely safe to use. Get DOT 3 or DOT 4 material and not the DOT 5, which is made with silicone oils. There are many brake fluid manufacturers and are available at garages and automotive parts outlets.
Glycerin is a common retarder used in many instances, but I do not see it a viable material in this case. While glycols evaporate out of the image film, glycerin is hydroscopic, which will attract humidity and never disappear. Because of this, it is used in places where it is desirable to keep the film flexible.
Another material that may be of some use to the printmaker is Soya lecithin. This is a natural product that is used as an emulsifier in foods and commercial products. It has an oily nature and dries at an extremely slow rate. I have found that a touch of lecithin added to the modifier will improve both the emulsification and slow the drying of the ink.
By adding the water reducible binder and retarder, the ink will lose much of its viscosity. This can be corrected by adding epoxy hardener and/or Mag to give the ink more body. When using Van Son or other rubberbased "quick setting ink", one easy way to add body and viscosity is by using epoxy hardener. I have introduced the concept in my paper on waterless lithography, and since the rubberbased inks are still the best ink to use, epoxy hardener is an excellent material to add. It can be used in conjunction with magnesium carbonate. Use a very small amount and grind it into a small part of the ink, increase the amount of ink as the mixture gets stiffer. Only hardeners for regular epoxy works as a body thickener - the 5 minute product does not have any effect.
Magnesium carbonate is another material for adding body to the ink when it becomes too loose. I have found that ink for waterless lithography should not be as greasy as for traditional printing, so the use of Mag improves the quality in this case also. It is possible to use calcium carbonate as a body additive, but from my experience I have found it not a suitable. Calcium carbonate, also known as Whiting, could be used in a pinch if Mag was not available.
Note that epoxy hardener will add tack and mag will decrease tack.
Since we are trying to incorporate a water bearing material into oil based ink, there may be some situations were increasing surfactants may help. These chemicals are highly concentrated and should be used sparingly. They will be present in oil based ink as they are used to wet some pigments so they take up the binder readily. While there are many commercial products available to industry, as artists we have a limited number from which we can choose. Golden produces two products that contain concentrated surfactants, one is Acrylic Flow Release, and the other is Universal Dispersant. They may not be necessary if the ink performs well. Ethylene and propylene glycols act a bit like surfactants and may be all that is needed. Lecithin is also effective as an emulsifier.
Producing your water soluble ink
For a small amount and in developing your skill to modify ink, I suggest you mix it on the slab with a putty knife. If you have Green Drop ink, then I suggest you use it as the modifier in a color suitable for adding to the oil ink.
Just new on the market, Daniel Smith has introduced water-soluble relief ink. In the limited experience with this new material, I have found it very encouraging and think it will make a considerable contribution to printmaking. I have found that the Daniel Smith ink does not increase tinting. This approach seems the easiest way to make oil ink water-soluble. It also does not dry too fast on the slab, but is difficult to use because it skins very hard in the container. This drying problem is the greatest disadvantage to the ink as cans become difficult to open.
Another good way is to use some of the available water-soluble resins and oils. The binding media I recommend is from the new water mixable oil paints now available for painters. Grumbacher, Windsor & Newton, Talens and others are into supplying pigments ground in water reducible linseed oil, as well as making paint medium for modifying the tube paint. There are a linseed oil, stand oil, mixing medium, impasto gels and less viscous quick drying medium produced by these paint makers. Since all will be manufactured from water reducible materials, I am sure others will work as well as the ones I have been able to try. The only medium available to me at present is Windsor & Newton Artisan water mixable products. I have found that both the stand oil and oil mix medium to be most suitable for what I am doing, but I would use the characteristics of the others if I needed a different type of ink. On drying by oxidization, the oil become waterproof to produce a permanent print as if printed with oil based ink alone. The water mixable resins become permanent as well
Ink requirement different for a litho press and "Sasha's Palm Press"
Because of the lesser printing pressure produced by the palm press, I have found that a stiffer ink is required to make a suitable impression. By using epoxy hardener for body, better ink is produced for this purpose. Depending on the image, you may have to modify the ink to get the most out of the plate. Large flats are difficult to produce with the palm press, even on smooth papers, but toner washes and line drawings come out perfectly. For printing with a regular litho or intaglio press, the ink can be much looser as the greater pressure will force the paper into the thinner layer.
Modifying the oil base ink for palm press
To the ink you will need for your edition, add epoxy hardener until the ink become fairly stiff. Do this by using a very little of the hardener and add a small amount of ink into it until it starts to stiffen. Keep adding ink a bit at a time until the entire batch is incorporated. To this now add a small amount of water mixable material (10-25%), such as Daniel Smith relief ink, Windsor & Newton oil paint mixture, stand oil or the linseed oil medium. If too much is added, the ink will become too loose for the palm press, so add magnesium carbonate to increase body. Using a small brayer, try the ink on the plate and see if tinting is taking place. Well-adjusted ink produces a clean background, while depositing a good thick layer ink the image. If this plate was printed on a regular litho press, the darker areas would come out completely filled in as the ink is spread out by the greater pressure. The palm press will just allow contact with the sticky ink and leave a good impression. If the ink is too stiff even for the palm press, it will be difficult to press the paper so that the irregularities in the sheet are common in the flat areas. Smooth paper and adjustment of ink viscosity will help in reducing "salt & pepper" areas. Rag papers can be printed with the palm press if they are softened before hand in a damp book to make the fibers soft and compressible. A protecting sheet of Mylar taped at one end and brought over the damp sheet will prevent any damage to it by the rolling action of the unit.
Modifying ink for regular litho presses
I have found several ways to make a good printing ink for the litho press, and still keep it soluble in soapy water. You can use the above formulation, but not as stiff. Magnesium carbonate is a good material to use on some images, but experience will show just the best combination for a particular plate. Much will depend on the oil-based ink you start with. While I prefer Van Son Rubberbased Plus for waterless lithography, I have used a number of different products, ranging from Van Son Sona Dry to Rembrandt Graphic Arts block printing ink. Since both of these contained a lot of drier, I added more retarder to bring printing more into line. Daniel Smith and Hanco inks all worked well enough also, but the characteristic of regular rubberbased ink seems the best to use.
Using the ink
Try the ink by rolling it out with a small brayer and applying it to a plate known to print well. If there is excessive tinting, then add epoxy hardener or more magnesium carbonate. You will find that quick rolling over the plate with lift the veil of ink from the background areas. Do not use too thick a layer of ink on the slab, as this will produce tinting and will have to be removed by a great deal of rolling after a proof on newsprint is taken. When printing with a "Palm Press", the ink will have to be stiffer to compensate for the lower pressure of printing. By controlling the viscosity of ink, you can effectively control the contrast of the printed image. While loose ink will reveal all the delicacy of the light tints, the chances of tinting increases. Stiff ink produces bright contrasty prints with no tinting problems. I generally use my ink quite loose at the point it just wants to tint. That way I can produce the most delicate passages present on the plate.
Sun Chemical DriLith W2
This well established company has produced ink for commercial lithographers in many countries and has developed a water soluble ink for offset lithography. I have been successful in getting a small sample of this black ink and found it worked very well except for the fast drying on the slab. Since it is formulated for commercial presses, the driers it contains are a necessary ingredient. I have been trying for sometime to get a full range of colors to test but with no success. I doubt that a company of this size would be interested in formulating ink just for the small amount of fine art printers, so finding some way to modify the ink is the only recourse. The addition of DriLith W2 to Van Son Rubberbased Plus worked very well, just as with Green Drop ink. Until someone else or myself can obtain a good supply of ink to research, it will only be a suggestion for a water cleanup system. I have been told that Sun Chemical may discontinue making DriLith W2 as the demand for it was not there. I hope this is not true.
Commercial products suitable for removing ink
The use of common vegetable oils to dissolve ink has been around for many years. This simple method is to first remove most of the ink from rollers and equipment with the oil, then use vinegar or soap to take off the rest. I have experimented with adding some odorless paint thinner to the oil so that cleanup is easier, yet the smell is not there. I have even obtained some water reducible canola oil in the hope that water or weak detergents can be used for the final cleanup, but the cutting action of straight vegetable oil is still very weak. I have researched the use of common motor oil or the more expensive mineral oil from a drugstore, instead of vegetable oil. These work without VOC's getting into the atmosphere. I feel the problem with these methods is the slow messy way to cleanup after a printing session is undesirable for most printers.
In my research I have found that many commercial products can be used to remove unmodified oil inks commonly used by printmakers. Because of the environmental concerns in the commercial offset printing industry, there are a number of suitable blanket wash products that printmaker can look at. One of the more popular is "California Wash" made by Varn. It can be diluted with 30% water to make it less objectionable, yet still retain its' cleaning action. Other products such as "Ecolo-Clean" will do a satisfactory job as well. The hydrocarbon content is still there, but at a much reduced level to using straight paint thinners. Many manufacturers of printing supplies have suitable safer products that printmakers should investigate.
A promising product from Europe has just becoming available in North
America. It is "Vegetable Cleaning Agent" or VCA.
Produced from modified vegetable oils into an ester or alcohol, it does an
excellent job of dissolving oil ink. It is completely soluble in water and
biodegradable as well. This means that some printers have suggested cleaned up
residue can be put down the drain, but I oppose that practice as pigment
particles will be present. While it is quite expensive compared to other
cleaning agents, much less is required to do the job. The North American
distributor is Akua-Kolor in New York. It is an
aggressive cleaner so you must use rubber gloves when handling wet materials. I
have heard that
It is very easy to make up good cleaning solutions from common household products. For a number of years now I have been using a simple wash for my 3-part roller, linear offset blanket and other equipment. It is made up of PineSol, a solvent and traditional green Palmolive detergent. To increase the cleaning potency of PineSol, I add about 25% turpentine to the bottle and shake to produce a milky solution. I prefer turpentine because of its greater cutting action on ink over hydrocarbon solvents - besides the odor is less obnoxious to me. I add Palmolive traditional green household detergent in small amounts and shake until the solution clears up; now the emulsion will never separate. Paint thinner can be used instead of turpentine, but with less effect. For a still less noxious additive, odorless paint thinner is the one to use, but with even less cleaning effectiveness. Lestoil is a product similar to PineSol and can be used as a base instead.
Simple Green is a good general cleanup solution to remove any oily film left
by the two above products but I have never really needed it as plain water
lifts off all the grime. Mean Green is a new product similar to Simple Green
but stronger. It comes in a spray container and seems to be one of the better
materials for cleaning up inks. Fantastik is another
commercial product that has good grease cutting action to remove ink from
plates and slabs. Its' active ingredient is sodium hydroxide, which is hard on
ones hands. Castrols' Super Clean is very effective
also, but comes in a spray bottle and gets expensive. It has become available in
4 liter containers. Force Degreaser is an excellent concentrated product
There are many citrus thinner containing degreasers on the market as this natural product from orange peels has good grease cutting action. Most of these products are water-soluble and do a good job of removing ink from roller, slab and plate. Their cost is greater than the old standby products and not available everywhere.
I have found that I could formulate fairly good ink removing solutions, using sodium metasilicate, sodium hydroxide, sodium laurel sulfate, the new super kitchen detergents and some solvents. This becomes a liquid soap that will clean off ink very well. The low cost of these mixtures is a factor some may consider.
Preventing cleaning up compounds from entering the sewer system
Cleaning the slab and roller at the same time
Scrap the slab with a razor scraper to get as much of the ink off the surface as possible. Use one of the wider blade scraper as this does the job much faster. Roll off excess ink from your roller unto newspaper. Give your cleaner a chance by removing as much ink from your equipment unto newspaper or paper towel. While any of the commercial products can be used, I prefer my PineSol mixture for most of my cleaning jobs.
The best method I have found is to lay a bead of the PineSol mixture on the scraped slab and spread it with your dirty roller. You will find the roller will slide and not turn because of the slimy nature of the solution. To give some grip to the roller, I originally use wet-strength towel or newspaper, but found that a gritty powder works and more convenient. After spreading the solution, sprinkle some powder such as Comet or Dutch Cleanser into it. Rolling over the slab now will turn the roller and help wet and remove the ink. Castrol Super Clean is not a viscous solution and does not require anything to prevent the slippery surface on the slab. After the ink seems to be dissolved, take a page of a newspaper and place over the spread out cleaning solution. You can now roll off the dirty ink from the roller until it is about dry. Use the newspaper to take up the ink from the slab. Plain or soapy water will remove the residue and leave the roller absolutely clean. The newspaper is used to mop up the remaining ink on the slab, and then thrown into the garbage container. Plain water is used to clean the slab. A cloth with PineSol solution is used to clean ink knives etc. Commercial products work much the same way to clean rollers, slab and equipment. By disposing of the newspaper that has all the dissolved ink on it, we prevent ink and the cleaning chemicals from getting into the sewer system.
Another material I use is a wet strength paper used by garage mechanics. This is wider than Bounty or other paper towels and can be torn to the width of the roller. I place the sheet on the slab over the scraped ink, then pour a bit of PineSol cleaner in a line the width of the roller. This produces enough texture to grip the rollers and make them turn. After the ink is broken down on the roller, it is rolled off unto scrap newspaper and wiping down with more PineSol and water. Water can be added to the slab as the paper has more than enough strength to take the abuse. The slab is rubbed down with the paper and thrown in the garbage.
Ink for intaglio
Making intaglio ink water-soluble
The same concept is used to make intaglio ink water soluble as is used for lithographic ink. As long as enough water soluble oil molecules are present, then a strong detergent will break these down and help strip off the ink from plates and equipment. Since the demands of intaglio ink is not as great as the rejection characteristics needed in lithography, modifying etching ink is much easier. In my early research, I used a multitude of materials, but since finding the water mixable products, I feel these are much easier to use.
My first use of modified ink
I have found that some intaglio ink does not have enough pigment if only the clear Artisan water mixable media is used. If you find the intaglio ink you are accustomed to using produces a weak print when modified with the water mixable oil, then more pigment has to be added. To eliminate the need to grind in dry pigment, I suggest you use an appropriate colored paint that is ground in water mixable oil. There are a number of these on the market these days. The amount will vary with the type of ink you use, but start with a 25% addition of the water mixable oil color. For intaglio, there is no need to add magnesium carbonate or any other materials. The oil paint is easily mixed with ink and produces a smooth spreading and wiping ink, without the need of easy wipe. I am sure that if a large quantity was premixed and stored in the original intaglio ink can, then the drying of the surface and subsequent dried particles can be largely eliminated.
Because of the greater pigmentation of lithographic ink, I have found that it can produce beautiful images when modified with the water mixable media. By adding a lower viscosity material, the ink becomes loose enough for easy wiping, eliminating the need for conversion media that is normally used with litho ink. Depending on the image, stand oil or the less viscous linseed oil can be used, but the pigmented oil paint works well also. I have been using Van Son ink in my research, but I can see that many other ink products should work as well. Since rubberbased ink is very slow drying when compared with intaglio type, then some of the more common printmaker's ink may be advisable for faster drying. Since there is a fast drying media available in the water mixable section, this could be used to adjust the drying time if necessary.
Daniel Smith water soluble relief ink
Now that there is water reducible ink available, it turns out to be a wonderful modifier to make intaglio ink water soluble. Since it is not as viscous as regular intaglio or lithographic ink, it works much as Easy Wipe compound as well. Because these relief inks are designed to dry like ordinary ink, the image becomes totally waterproof in a few days. Cleanup is very simple with any strong cleaning solution or the modified PineSol.
Akua Kolor water soluble intaglio ink
This company has produced a new product for printmakers that is being promoted for its’ non-toxic nature. I have been sent samples to test, but I feel there is not enough pigmentation for my likes. Since intaglio is not my specialty, I had the studio technician at the art department try it on his mezzotints. His opinion was the same as mine. I have also received the views of a number of others who have tried this ink and they are much the same. I have produced acceptable prints by adding dry pigment or Daniel Smith Waterbased relief ink. Since I see some printmakers are promoting it for their workshops etc., I suppose it suits some artists even at this low level of pigmentation. The suggestion from the manufacturer is not to use tarlatan as it wipes out too much ink. Ordinary newsprint is the best option. This ink could be the answer for most intaglio printers if the pigment content is increased somehow. If you are looking for a completely water soluble ink, then Akua may be the solution by adding pigment or mixing with other waterbased inks. I do hope there is more research and development by the manufacturer as we need this type of product.
Making your own water soluble ink
Because of the greater interest in water soluble intaglio ink, I have
brought back the early research that Alan Flint and I did at one time. It
consisted of using
As a starting point for your own research, I suggest the formula I have been
using. Mix 50 ml of
The use of Lestoil, PineSol, Force Degreaser, Fantastik, Mean Green, Simple Green or the alkaline silicates is all that is needed to clean up plates and equipment. Wet strength paper towels have served me well in most cases, except for plates with large areas of aquatinting. To help in getting the ink out of the depressions in the plate, use one of the soft plastic surgeons' brushes used for an operation scrub up. These are available from Lee Valley Tools Ltd., a Canadian company that has branches in the USA also. If you can find them elsewhere, these surgeon scrub-up plastic brushes are excellent. They have soft sharply pointed bristles that will never scratch even the plastic plates, yet can go deep into the grain and dislodge the ink. Wiping with a paper towel and flushing with clean water and drying finishes the job. Slabs and equipment is cleaned with Fantastik or any other household cleaner available. The surgeon brushes are very inexpensive and can also help you get the ink from your hands. Some orange scented hand cleaners supply similar brushes for cleaning fingers nails.
Conclusion of using modifiers
It has always been my hope to eliminate the hydrocarbon solvents for the print studio, and with this simple method I have succeeded in my own workplace. When proofing an edition before this development, I was reluctant sometimes to go through the mess and smell of the cleanup. Today, I have no hesitation to try a different color, as everything is so easy and much less toxic. While the future may bring a new line of commercial water-soluble ink as manufactures see a market for such a product, in the meantime printmakers can use these simple techniques to reduce the use of solvents in their studio. There will be some printmakers who reject the idea for one of many different reasons - such as liking the characteristics of a favorite ink. Some commercial inks are very difficult to replace, but with the many new water reducible materials coming on the market, these can be used to fine tune the ink you are using as you become acquainted with their characteristics.
I have been doing research into this area for more than six years and have found many ways to produce water-soluble ink, but with this present method, I think it is the simplest, with readily available materials. I will use other products to fine tune my ink for a specific job, but to put all my research into a paper is not feasible at this point.
I have come to the conclusion that oil based ink produce the richer colored prints and prefer these inks. Since I can cleanup the studio with any number of grease removers, I wonder if the quest for a completely watersoluble inks is necessary. We do not know how well the new products will last in comparison to traditional oil based ink. I will continue to look at what is coming available in waterbased products, but I am becoming not that concerned. Oil based ink alone is not toxic, just the cleaning up operation that requires hydrocarbons. Unlike the commercial printers that used large amount of ink on presses and the need for large quantities of solvents, the artist printshop can completely reduce their use by substituting other cleaning agents. Until industry finds better water reducible binders, we may have to put up with other materials.
List of suitable water based cleaners
1. Lestoil - an old
reliable product sold in grocery stores.
2. Pine-Sol - another old reliable cleaning product from the grocery store.
3. Simple Green - a readily available cleaning material.
4. Mean Green - a new degreaser stronger than Simple Green
5. Force Degreaser - produced by Force International for the machine tool trade.
6. Fantastik - a common household cleaning product
7. Citra Solv - a citrus containing cleaner which is water-soluble. In
8. Lloyds Citrus Clean LX2000. Available through some machine tool suppliers.
9. Crystal Citrus Degreaser, Product No. C6000. A heavy duty cleaner available from Princes Auto in
10. Zep Citrus All Purpose Cleaner. Available from Home Depot. A less vigorous cleaner than the
11. VCA, Vegetable Cleaning Agent. Used in
12. Castrol Super Clean, an aggressive solution available in automotive part suppliers and others
Modified March, 2003