I will put in my two cents. After seeing Dr. Efners Pysautotype on glass,at A.P.I.S.'07 I became very exited. All of my own work is on glass, Pt/Pd/Au and Gum dichromate. I loved the delicate nature of the physautotype on glass.
I began with 1% Graphic Rosin, heated as per Howards instructions, in denatured alcohol. Development over Oderless paint thinner. Although I had no troble(i'm leaving out my false starts and screw-ups here), I was never satisfied with the quality of my coating. Until I began adding WATER. Up to 30% water.70% ethyl alcohol. Gose on clear and smooth. Dries white and smooth, and develops cleanly,without over-developing. But use ODERLESS paint thinner. Avoid anything that has Stoddard Solvent.
Oh, um, Apparently white spirit, which is what i'm using, is stoddard solvent. What's your odorless paint thinner then? I've never heard of that. Over here the standard is white spirit mostly. It'd help if we used as specific of names as we can as far as chemicals we're using. I think there might be something along the lines of "better than white spirit" paint remover/thinner.
Originally Posted by wildbillbugman
The brand of odorless paint thinner which I am using is Sunshine brand. The Material Safety Data Sheet (reqired fo just about everything in U.S.) simply states "synthetic hydrocarbon" I would be very surprised if you don't have something similar over there.. In general, things that have strong odors will tend to be more volatile and cause faster development.
What gave you the idea to add water ?
how much longer does the mix take to dry ?
My apology! I meant to say Sunnyside Odorless Paint Thinner(not "Sunshine"). I was writing late last night. If you look up the (U.S.)MSDS
You can probably find something similar in U.K.
For rosin solvent, lately I have been using retail 70% Rubbing Alcohol.
I takes about an houer to dry on glass.
"What made me think of water?" I thought(correctly) that slower drying would cause better levaling of the rosin. I have been developing coatings for glass(industrialy) since 1974.
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Oh but aren't you using a completely different alcohol to what Niepce & Daguerre were using then? Rubbing Alcohol is very different from the 95% denatured alcohol that is usually recommended. If you're using 70% rubbing alcohol that's already diluted with water. I might try adding a bit of water to my solution the next time i try. I coated two plates last night one right after the other; one had the opalescent/rainbow-y effect and the other one didn't and was just white & milky. I'm hoping the opalescent one is the one that is going to work. Just letting it expose under the UV tanning box right now.
See, this process *is* simple but confusingly so because you can have so many variables and still get a result. We're getting so far away from the original concept, it'd be safer to call (some of) this Modern Physautotype, but what Bruce has been up to is more similar to Traditional Physautotype, using lavender oil resin etc.
Gee this "modern phsautotype" with rosin is fickle.
today i got what looked like an fairly even coating on a glass plate.
nice and frosty, not too much pooling.
tried a contact print for 1hr, 45 mins in midday cloudy conditions
amb temp 18'c, uv index about 9.
I could see a very faint image, so into the d tank with kero
RATS after only 15 mins the plate had completely cleared, not fair.
Bill Is kero this Stoddard Solvent ?
Last edited by brucej; 12-10-2007 at 10:02 PM. Click to view previous post history.
Bruce- "Stoddard Solvent" is an old timey industrial refference to a particular petrolium distilate. It is realy a mixture of aliphatics and aromatics. It is smelly,with a low vapor pressure. But it is cheep. That is why it is used in cheap,smelly paint thinners.
Heather- Original denatured alcohol,and the type that Howard uses,is mostly ethanol,with methanol added so that one cannot drink it. (Unless,that is, one aspires to be blinde or dead.)
I started using rubbing alcohol (70% ethanol/30% water) only after I found that the adition of water to denatured alcohol improved coating chracteristics. Often,denatured alcohol absorbs water from the air, if its been opened and siting around awhile.
I have also used 70% isopropyl alcohol,with results virtualy identical to ethyl alcohol.
Bruce, Stoddard Solvent is known as White Spirit here in the UK; it might be called that in Australia too. I agree about the modern physautotype being fickle. I've only just got another (partial) image after a whole week of coating plates every night and doing exposures under my UV light every day and just getting nothing every time.
Bill, I've not had a problem with using Stoddard Solvent to develop my plates, though. I finally got a tiny bit of an image on a plate today. Maybe it's
just my method of developing. I use a large tupperware-type box with lid and just a glass ashtray with a little bit of white spirit in it. I use cut-up pieces of cardboard tube (from a used up roll of plastic wrap) around the ashtray to put the glass on it (face down) and then put the lid on the box and leave it for however long I think is necessary. Doesn't stink up the bathroom I work in then and creates a little fume box.
I always thought rubbing alcohol was isopropanol alcohol but apparently not (after reading wikipedia again). I don't think we can get rubbing alcohol over here, it's usually only isopropanol alcohol which is available if you ask the chemist nicely and tell them you're using it for a valid reason.
I might try the adding water method, though my plates do take a few minutes to dry anyway.
Thanks bill, looks like kero is ok then for rosin, i can buy white spirit here in Oz, we used to use lots of it back in 1980's cleaning banks and wipers in the step by step telephone exchange i used to work in, untill technology replaced it
Heather i use about 100ml of kero in my d tank, in a flat plastic bowl, the kero is spread out across the bottom of the bowl. covered with aluminium foil, plate sits on 4 bits of pvc, you can test your development process by simply coating a glass plate and let dry (dont worry about getting a perfect coating) and put straight into the d tank, with enough time it should go clear. for me today it took less than 15 mintutes @18'c for the plate to go completely clear (not my desired result)