DIY laser transfer paper with water-based "gum" glue
2012-07-08 by Robin Whittle
Here is a potentially novel way of making laser toner transfer paper at home. It requires some ~140gsm card (at about 180um, thicker than standard 80gsm laser / photocopy paper, but not as thick as the 200 to 220 gsm card which is more widely sold) "paper gum" (water-based, clear glue from a craft shop), kerosene, acetone, and a hot air gun. In the future, I will place an updated version of this material at: . http://www.firstpr.com.au/pcb-diy/ The purpose of a laser printer transfer paper is to accept the toner from the printer and then allow it to be transferred to another surface. A common use for this is to transfer the toner onto copper-clad PCB laminate, where it will be used as a resist for etching. I am using it for other purposes, which I will describe in the next few months. Here are my thoughts on the desirable characteristics of laser toner transfer paper. The paper should run smoothly through a laser printer. I think this means it should be 80gsm to 140gsm or so. Thicker card, such as 210 gsm, is stiffer and may not always feed so well. The Pulsar transfer paper: . http://www.pcbfx.com/main_site/pages/products/transfer_paper.html is about 228um including its gum layer. It weighs in at 172gsm with its coating (10.37 grams per US Letter sheet with 16.577 sheets per square metre). The Pulsar paper feels a little stiffer than the card I am using. This card weighs in at 145gsm (9.1 grams per A4 sheet, with 16.03 A4 sheets per square metre). I guess it is 140gsm when dry. The printable surface of the paper should not be paper itself, because the toner will melt into the paper fibres, making full removal of the paper impossible. The only way I know of achieving this is to coat the paper with gum, such as dextrin (a starch). The gum surface should be smooth, but not necessarily shiny. Perhaps it helps if the surface has a matte finish, so the toner is less likely to move around due to electrostatic self-repulsion, or vibration, between being deposited from the drum and being melted by the fuser rollers. Surface roughness may or may not matter in the final application, but for one of the purposes I am pursuing, it is important that the surface be smooth. The Pulsar paper is quite smooth and the Olathe Post paper I wrote about in a recent message (30334) has an irregular surface. Both the Pulsar paper and the DIY paper I am about to describe were good for my application which required a smooth gum surface. The Olathe Post paper was not suitable for this application. The paper would ideally be insensitive to moisture levels at the time of printing. With both the Pulsar and Olath Post paper, I found it best to humidify the sheet just before printing, such as by placing it face down on a wire rack one or two cm about some vaguely warm water for a few minutes, with a tea-towel on top of the paper, which had previously been resting on the rack. This level of moisture is not enough to make the gum sticky, but (for me at least, using Brother HL-5250DN and HL-4040CN printers) solve the problems which occur when these papers were too dry, including the toner being fused together but not actually bonding to the gum, presumably because the gum was too dry and hard. The paper which results from the process I am about to describe has a thinner gum layer than the Pulsar or Olathe Post papers. My initial tests indicate that it is not so fussy about moisture levels, since I can print on it when it has just been hot-air dried, and the toner bonds perfectly. I think this is in part due to the gum being thinner and not so hard a surface, since its hardness depends more on the underlying paper fibres. However, the nature of the starch/gum itself could be quite different to that of the other two papers, with its thickness not being such an issue. The DIY paper I am about to describe seems good in terms of surface flatness (depending on how evenly the liquid gum-water mixture can be distributed), but there are some difficulties making the whole sheet nice and flat before printing. Ideally, the sheet should be absolutely flat, rather than having a curl in any direction, because such curls will make its travel through the printer more error-prone. Finally, the transfer paper should be easy to remove from the new surface with water. The Pulsar and Olathe Post papers peel off nicely after a few minutes in cold or warm water. Any residual gum/starch is easily removed. This DIY transfer paper is easy to remove too. In my initial trials like this, the whole sheet peels cleanly away, taking most or all of the gum with it, after two or three minutes soaking in warm water with a little detergent. The major difficulties making transfer paper seem to be obtaining the gum/starch and spreading it thinly on one surface without causing the paper to become soft or deformed. Here is how I solve these problems. Step 1 (I assume people are wise to the dangers of chemicals, fires, etc.) Make a mixture of 1/3 kerosene 2/3 acetone. I do it by weight, but by volume would be fine. Place the 140gsm card on a flat surface such as a Formica table-top or a sheet of glass. Spray or otherwise spread the mixture so it soaks the entire sheet. (I put my mixture in a Windex sprayer.) Then, using a light, fine, squeegee, or perhaps a roller of some kind (or perhaps tissues) remove all the excess kero/acetone from the sheet and put it out to dry for five or ten minutes. The acetone will evaporate within a few minutes and before long the somewhat kerosene-damp sheet will smell only of kerosene. I figure we have a well-dispersed, but not saturating, body of kerosene in the whole volume of the card now. This is our temporary waterproofing system. (Other attempts at DIY transfer paper involve spraying expensive pressure-pack leather/cloth waterproofing liquids onto the paper or card, making it permanently waterproof, which significantly delays the final step of washing the paper or card away.) I have prepared some 80% gum, 20% water (by weight) and stirred it well. I add a few drops of red food dye so I can see where this gum is as I spread it. The gum I used is sold as "Paper Gum": . http://www.miyartcrafts.com.au/Craft-Smart-Paper-Gum.html It is a clear, uncoloured, liquid, not milky and not a paste. The package states: > ... adheres to most surfaces, including metal, plastic, glass and > ceramics. For scrapbooking and memory craft it has distinct > advantages. It is pH neutral. It dries clear and will not > yellow with age. Equipment cleans up in water. I assume this is a dextrin gum of some kind. This is not "glue", "PVA glue" or any such thing. It is *gum*. It is a clear, viscous but smoothly flowing uncoloured liquid which can be thinned with water. The dry gum will dissolve in water, though it takes a bit of rubbing if there is a substantial blob of it. It is possible that the term "gum" is more widely in Australia and New Zealand for this particular type of adhesive. Googling for: "clear gum" ml turns up similar products in .au and .nz. One product which seems to be the same or similar, and which is available in all countries can be found with Googling: Pentel "roll'n glue" . http://www.pentel.co.uk/products.asp?group=5&type=23&pid=198 There's a 300ml refill bottle for these. I am reasonably sure that this substance would work exactly the same as the "gum" I used. This Australian page: . http://sewingcraft.com/wordpress/?page_id=2072 lists 16 types of liquid adhesive found in craft shops. The one of interest is: Helmar Professional Acid-Free Glue: > ACID-FREE, (NEUTRAL pH),SETS CLEAR, NON-TOXIC, FLEXIBLE BOND, WILL > NOT YELLOW. Helmar Acid Free glue has been specifically designed for > memory albums, book binding, mounting photographs, preserving old or > precious books, documents, scrap books, most craft projects, etc. > Featuring excellent adhesion to dense papers, high flexibility, long > term life of the bond. Sets clear, dries quickly and will not yellow > with age. Non-wrinkling ! ACID-FREE ! Neutral pH level. This product is surely suitable for the process I am describing. It is from the USA - $7.45 for 8.45 fl.oz. : http://www.helmarusa.com/index.php?page=shop.product_details&flypage=vmj_naru.tpl&product_id=8&category_id=1&option=com_virtuemart&Itemid=7 I have just discovered that "envelope gum" can be purchased in small containers, such as: . http://www.crafterscompanion.com/Envelope-Gum_p_32.html . http://www.crazicards.co.uk/crafters-companion-envelope-gum/prod_698.html This is probably different from the glue I used. It is meant to be applied to paper and then left to dry, to produce a traditional gum layer which can be moistened and used to seal the envelope. Perhaps this material would be suitable for making transfer paper without any mucking around waterproofing the paper beforehand. Step 2 I lay the sheet on some scrap paper, such as a few layers of newspaper. I pour some of the gum-water mixture on the card and using a kitchen sponge spread it quickly and reasonably evenly over the card. The kerosene greatly reduces the rate at which the gum-water mix soaks into the card. However, it does soak in to some extent and this stage needs to be done as quickly as possible. I found the sponge worked reasonably well in producing an even coating. I also found a light squeegee (for cleaning windows) helped spread the mixture evenly. It is possible that a roller would work well. Perhaps if the mixture could be sprayed from a compressed air spray gun - this might work really well if the drops were very fine and evenly distributed. I have a spray gun. Later I will try using it for both the kero-acetone stage and for distributing the layer of gum. As soon as there is a reasonably even coating, dry the sheet with a hot-air gun. To do this, I place the sheet on a dry sheet of newspaper (since the first sheet now has gum where the edges of the A4 sheet were) This will cause it to curl to some extent, but it is not as bad as if I had not used the kero-acetone mixture. The drying will get rid of most of the kerosene. If the gum-water mix is too viscous and/or is in too thick a layer and/or if the drying heat is too intense then bubbles may develop in the gum coating. This is unacceptable, so I suggest less aggressive drying. While the sheet curls somewhat, it does not become soggy or wrinkly. The curl can be reduced by running the sheet, on its own, through a laminator. This will dry off more of the kerosene. Now, the sheet is ready for printing. I haven't investigated storage, but I think that if I make a bunch of sheets and press them together in a flat stack, they should be fine to use at any time in the future, and will probably not be as curled as they are initially. After transfer (I am using a laminator, but some people use an iron to melt the toner onto the copper-clad PCB board) the paper can be removed with water, or warm water with a little detergent. - Robin