This is a re-posting on the subject of solvents gleaned from 40+ years of printing experience, and is designed to be more searchable than a comment in the middle of a discussion.
Do not be fooled by the ‘odorless’ solvents on the market, they still emit fumes that are dangerous to breathe. California Wash is mostly Naptha (which you can buy at the hardware store for a third of the price) with several cancerous chemicals added to slow evaporation. With a child involved I would make sure to clean and air forms out of the house, and keep used rags outside as well. Do not put rags into an airtight container, it is very dangerous and could cause spontaneous combustion.
(1) Kerosene is the best general solvent, it is slow to evaporate and will clean most grease and oil that might be on your press. It is used in commercial garages for their parts washers. It is used for jet fuel, but actually burns rather slowly.
(2) Mineral Spirits evaporate a bit faster, and the low-odor aspect is a selling point – just remember you are still inhaling fumes, even if you can’t smell them. It is good for removing adhesive residue, and I have even used it at times to help remove labels from packages and book jackets.
(3) Naptha is the basic ingredient in almost all type and roller washes including the much touted California Wash, and is sold as Coleman stove fuel. Why anyone would pay $30-$40 for California Wash when Naptha at the hardware sore is so much cheaper I’ll never understand. Naptha is substantially more flammable and evaporates very quickly. It is good for removing ink and if used excessively will also remove paint, so care is needed while using it.
(4) Lacquer Thinner is a much stronger solvent, fast evaporating, highly flammable, and will remove dried ink, oil, grease paint and will activate some kinds of plastic. I use Lacquer Thinner to remove the paint from the fronts of typecases before repainting. I have successfully cleaned very dirty type with it, but I use it very, very sparingly, and never in a close environment. It will take the finish completely off of wood type, and will re-activate the glue used to hold zinc and magnesium plates on their bases.
(5) Denatured Alcohol also evaporates quickly and is very flammable, but for some reason it is the best cleaner I have found for old, dirty printer’s furniture. I also will use it to clean a form or tympan in the middle of a run, because it evaporates so quickly and leaves very little solvent on the cleaned surface.
(6) Acetone is probably the nastiest of all of the solvents readily available at you local hardware store. I have used it at times to dissolve dried ink in half-tone plates. That is the only use in a printshop I can think of, and I haven’t had the need for any for thirty years. If you touch it with your finger you can taste it in your mouth. It will melt most plastics and I can see no reason to keep any in a working shop.
Caution: Any solvent will build-up fumes in a closed environment, and can cause flash fires. Solvents should always be used safely, sparingly and in a well ventilated environment, and capped securely when not in use. Appropriate safety cans should always be used, and larger amounts should be kept in fire-rated safety cabinets. The only solvent I buy by the gallon is Kerosene, the others that I use regularly are stored in the 32 ounce can that come from the local hardware store, and for regular shop use are stored in brass safety cans, because brass will not create a spark.
Take the time to read the MSDS safety sheets for any solvent you are using or thinking about using. You will be surprised at the actual ingredients (many items sold as ‘Green’ are anything but, and many citrus-based cleaners might smell nice, but can do as much or more damage to the environment than oil-based solvents), and hopefully will realize that the additives used to “enhance” the basic solvents listed above add to cost and make them more dangerous to handle. Do not mix solvents together, I repeat, Do not mix solvents, it is very dangerous.
Also, there is no place in the printshop for Gasoline unless you have a press that is powered by an internal combustion engine, in which case you had better have a really good exhaust system. In the early days before electricity made it to the most rural environs, shop machinery was run off of one large engine through a belt-and-pulley arrangement. If the exhaust system leaked or was obstructed for any reason it could kill the occupants by carbon monoxide poisoning.
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This is wonderful information, I saw the post, and I wished there was a way to link directly to your comment filled with very valuable info, but now you’ve done it better. Thank you!
Thanks you for the detailed information it will be very useful.
I like your article Paul, but personally, I’m not convinced that acetone is any better or worse than some of the other solvents we use. If anyone is interested, here is a link to a public health statement for acetone which I found on a US Government website:
For me, the whole question of what solvents to use is a tough one to answer. After being in printing for a long time I know what works, but can I really say that my choice of solvents is the best compromise between what works well and what has the least health hazards? No, I can’t say that.
What I do, for myself, is listen to experienced people like you, and read what I think is credible information on the web, and draw on my own experience which goes back to 1959 when I first ran a press in high school, and read ingredients labels, and then make the best decision I can.
I also think it is important to minimize my exposure by protecting my skin from direct contact, using as small an amount of solvent as possible, using the solvent for as short a time as possible, and using it in a well ventilated area so that the fumes are carried away as quickly as possible. (I admit I should do better in these areas, though).
I am right handed and the skin on my right hand is permanently slightly more shriveled and old looking than the skin on my left hand. This is because I didn’t take all the precautions I should have during my working life.
My reference to Acetone was a practical one. The other solvents mentioned will do most all the solvent-based jobs around a shop (and remember the recommendations were aimed at the smaller shop that is represented by the bulk of the conversations on this site). Sure, there are other solvents with practical industrial applications, but I do not know of a real reason to keep Acetone, or MEK in a small shop. Of course, if you had fingernail polish to remove, that’s another story. And after spending a few minutes reading about acetone exposure and it’s extreme volatility, my thoughts on the subject are not persuaded to change.
I definitely agree with you about not using MEK. And, you have a point about acetone too. I can see where it would not be the easiest solvent to use, especially for someone not familiar with it.
Interesting diagram you just posted.
This is terrific information, Paul. Thanks for posting. One question: Does anyone wear a mask while using solvents? Are there masks that filter out solvent fumes? I want to live long enough to print lots of stuff, so I cut my risks wherever I can. :-)
I’ve never used a mask, although at times I’m sure I should have. Here’s a link that gives a pretty good description of particle and vapor masks:
Does anyone use mineral oil (i.e. baby oil or similar)?
I have a very (very!) small operation in my nearly windowless basement, so I really can’t have much in the way of fumes at all. I’ve been using mineral oil since I first learned block printing in college. It seems to me to work fairly well at cleaning up most of the ink, and then I get rid of the last residue with just a little mineral spirits right before I leave the room.
Paul…. your article is indeed well recieved. Thank you for it.
I’d like to point out one thing, though: The kerosene sold as fuel in many parts of the country may contain various additives that may not be too good for you or your rollers. Plus it does tend to leave a residue which can cause later inking problems. I’d recommend that mineral spirits be elevated to the number one spot, and kerosene dropped to number two.
sure its all not good for you
but what should be emphasized
is good ventilation
after late 60’s
every offset job shop i worked in
press room had a dedicated ventilation system
if you are really worried about solvent fumes
put in a good exhaust / ventilation system
suck the bad air out
@wcp This list is more in the order of refining, although I do find Kerosene to be rather all purpose for me. I will generally wash-up my press with Kerosene, but if I have to do a quick turn-around I will do a final wash with Naptha. Washing rubber rollers with Naptha will dry them out and seriously reduce the life of the roller. Same with type, except for a quick wash-up during a run when I prefer something that evaporates quickly, Naptha if I have a few minutes, Denatured Alchohol if I’m in a hurry. I’ve never found Kerosene (which is also known a Paraffin Oil) to really leave a residue, not after it has completely evaporated, but it takes several hours to completely evaporate. Apparently there are two weights of Kerosene, one which is sold for lamps and portable heaters, which is a lighter refinement, and a heavier Kerosene which is used for heating oil.
I tend to use Mineral Spirits more sparingly because I find it to be little more effective than Kerosene, but more of an irritant to my eyes and skin. I understand that long exposure can cause nerve problems, so I prefer to limit such.
The reason I use Kerosene is because of its low volatility. Years ago, when I was at Hatch Show Print, the local Fire Marshal had me pour a small amount of each solvent into the lids of several ink cans (this demonstration was done outside, of course). He then had me toss a lit match into each solvent. The match in Kerosene did not ignite the whole solvent, it just continued to burn with a slightly brighter flame until the fuel provided by the match was exhausted at which point the flame went out. The other solvents burned in a flash, most of them igniting before the match came into contact with the solvent. The increasing toxicity of each solvent on my list should also be taken into account. I encourage all printers to read the available online information about every solvent they use. My list is meant for practical application in a small commercial or home shop, although when I worked in larger commercial settings the applications were not very different.
Thanks for all this wonderful information! My studio/shop was moved to the basement of our new home when we moved back to Canada. I wan planning on getting an art studio air cleaning system for this space. Last Fall I was coming down our back laneway and saw a Bionaire air cleaner sitting out back of our neighbor’s home. It was with a pile of stuff that had not sold at their garage sale, with FREE sign on it. I brought it home, found it had new filters inside. There is a function for adding aromas to the cleaning action that does not work, but the air cleaning function works GREAT. I have it mounted in my press area now and use it every time I print or have to clean anything. Since I have this air cleaner, I feel much safer working in an enclosed space in the winter months. This is an older model, but the replacement filters are readily available at Canadian Tire.