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autolisp
04-08-2019, 05:29 AM
I am going to re-tube some oil paints. They are W&N water miscible oils and have become 'stiff' and difficult to squeeze out of their tubes. I want to make them 'looser' and easier to use. They have to be re-tubed from 120ml into smaller 60ml sizes to fit in my new french easel drawer. What would be the best additive to make this possible?

RomanB
04-08-2019, 05:58 AM
WMOs stiffen irreversibly.

autolisp
04-08-2019, 06:09 AM
WMOs stiffen irreversibly.

Are you stating that WM oils cannot ever be 'loosened'?

RomanB
04-08-2019, 06:35 AM
Are you stating that WM oils cannot ever be 'loosened'?

After becoming stiff? Of course. It happens because oil binder polymerize, such process is normal. WMOs are not like watercolors which could be just rewetted with water.

contumacious
04-08-2019, 10:31 AM
You have nothing to lose in trying to soften them up. The longer you wait the harder they will get, eventually they may end up too hard to save - which might be the case for some of them already. If the paint at the bottom of the tube feels softer than the paint near the lid, then the odds are pretty good that you will be able to save most of those.

If they won't come out of the tube, unroll or cut off the closed end of the tube on the end opposite the lid, and squeeze the paint out by flattening the tube with a brush, metal cylinder or dowel rod on your palette. When you have most of it out, cut the body off the tube off at the top at a point where it is totally flat and dig the remaining paint out of the top part of the tube. Be aware that near the tube opening is where you are most likely to find hard chunks of paint so inspect that paint before you add it to the pile of softer paint that you squeezed out the end.

Slowly work some oil or medium into the paint with a heavy palette knife or a muller, on your palette, a marble slab or flat glass plate. If you add too much oil you will end up with overly thin paint, so go in small increments. It won't take a lot of oil / medium to thin it down. Mix in the added material thoroughly before adding more. You can use *WMO Linseed or other WMO oils, or a WMO medium. I wouldn't use a fast drying medium for this. Slower drying is better for extending the life of the paint. Add the oil / medium slowly so you don't end up with too thin of a consistency. If they end up with a texture you like, then you are good to go. Put the paint into new empty tubes or wide mouth syringes.

*You can also use regular drying oils such as Linseed, Walnut, Poppy Safflower etc. but they will become less water miscible depending on how much you add, possibly to the point that water won't mix in at all so if you want to retain the water miscible character, use WMO oils / mediums. Slower drying oils / mediums be they WMO or regular are going to help keep the paint soft longer, but will also produce a slower drying paint, so keep that in mind.

autolisp
04-08-2019, 11:25 AM
contumacious. Thanks for confirming what I suspected. A lot of the tubes of paints I have have not been opened, so I think I should be OK. I brought these water miscible paints as a job lot in a jumble sale (and they were a real bargain price) quite a few of them are in unopened tubes. Although they are water miscible I often use them as 'ordinary' oil paint and use a odourless turps with them so I think I will try thinning them with 'washed' linseed oil. As you say. I have nothing to lose especially at the price I paid fro them.

contumacious
04-08-2019, 11:31 AM
You are welcome. Let us know how it goes.

Gigalot
04-08-2019, 12:55 PM
Before opening, put your tubes into a very hot water. That helps to soften paint and to open tubes.

AnnieA
04-08-2019, 02:32 PM
I wouldn't recommend trying the following idea without thoroughly checking it out with some of the more experienced WC painters first, but if it sounds OK to them, it could save some time:

When I first tried oils some time ago, I dug out an old set of Permanent Pigments paint from a short oil painting workshop that I'd previously attended decades before. All of the paints were fine except for the Cad Red Light, which had hardened in the tube. Although I had been advised to toss it, my small art supply budget made it seem worth trying to revive the paint. I happened to have an old blender, so I removed the paint from the tube and put it in the blender, adding oil slowly as the machine was turned on. The experiment seemed to work and did result in a paint that seemed to be workable, albeit a little thin (I may have added too much oil). But who knows about the longevity of such paint in practice. At the time I was so new to oil painting that I didn't know empty tubes could be purchased and so stored the paint in an old prescription bottle. But that didn't work so well, so eventually the reconstituted paint was thrown away before it was possible to really assess how well it might work.

If anyone does try this, I'd like to stress that once a blender jar and blade is used in this manner for any paint made of toxic materials such as cadmium, it absolutely cannot be used for food prep any more.

I'm interested in hearing what others think of this...

autolisp
04-09-2019, 03:50 PM
Well. Today I opened a fresh tube of WM paint to compare with the ones I had. To be honest I could only detect a small increase in thickness. These tubes are the 'earlier' large tubes. Looking at the exposed innards I think the problem was that due to the quantity of paint in the tube and the 'what looks like quite square ends on the tubes'. I could see that when squeezing the tube from the bottom it would force the paint up against the shoulder of the outlet end creating a dam effect. Giving the impression of over-thick paint making it very difficult to get out of the tube.

I took out about 60ml of the paint and using a broad palette knife on a sheet of glass I added a couple of drops of washed linseed oil, in all about the size of two peas, and mixed it well. The effect was a paint with the feel of normal oil paint similar in fluidity to tooth paste or 'normal' oil paint. I added it to the new tube and using a pair of forceps, stood the tube upright in a bowl of boiling hot water. This further softened the paint allowing it to fill the tube whilst displacing any trapped air. When I saw that the trapped air was no longer rising through the paint I placed the tube upright in a bowl of cold water until the paint solidified. I crimped the end of the tube using a pair of canvas stretching pliers and labelled the tube ready for use.. I will now tackle the rest of the tubes over a period of time.

contumacious
04-09-2019, 05:06 PM
Sounds like a good way to do it. Did you notice any oil separating from the paint when you heated it up? That is about the only unwanted thing that I could think of that might happen with heating to that temp.

autolisp
04-10-2019, 04:58 AM
Sounds like a good way to do it. Did you notice any oil separating from the paint when you heated it up? That is about the only unwanted thing that I could think of that might happen with heating to that temp.

No, none at all. Mind you it was only heated for a very short time as the tube was almost totally immersed in the water and the aluminium transferred the heat to the paint very quickly.

autolisp
04-11-2019, 03:59 AM
What I previously forgot to mention is that all my linseed oils and odourless mineral spirits have 2-Butoxyethanol added to them to make them water miscible. This make cleaning-up a lot easier.

MarcF
04-11-2019, 01:31 PM
How does one put paint back into a tube?
The difficulty in putting toothpaste (much the same as paint) back into the tube is proverbial. Kind of like unscrambling an egg. You could use a syringe and a hypo, I suppose. No, the paint wouldn't really flow through the hypo unless you really thinned it. So - you have this stiffened oil paint you squeeze out onto a palette, loosen it up a bit, squish it around with a palette knife, then... all I can think of is doing a painting with it. Maybe scrape it off with the knife and put it in a sealed container. But back into a tube?
Look, I used to be a tool designer (among many other things) and I had problems like this and I tell you, I'd be hard pressed to come up with a readily available solution. I almost don't want you to tell me because I know I'll feel stupid once I know the answer. Of course! Elementary! And absolutely it has to fit the new French easel drawer as well. I'm stumped. Sorry boss - no can do. That was my ready answer for problems like reversing entropy, inventing time machines, things of that nature.

sidbledsoe
04-12-2019, 05:44 AM
I only use solvent. Far less is needed to loosen stiff paint, it works faster, and it works better than oil. Adding oil dilutes the paint and lowers the pigment to oil ratio a lot more than solvent, you want tube paint to be your concentrated stock, not a dilution.
MarcF, you retube into new empty tubes.
I have never known of anyone putting paint back into the tube from which it was squished out of, you get the empty tubes at Jerry's or somewhere and stick it in the open butt end, tamp it upside down, and then crimp it down.

contumacious
04-12-2019, 07:16 AM
I only use solvent. Far less is needed to loosen stiff paint, it works faster, and it works better than oil. Adding oil dilutes the paint and lowers the pigment to oil ratio a lot more than solvent, you want tube paint to be your concentrated stock, not a dilution.


Some folks don't want to use solvent so that is not an option for them, otherwise I would say that solvent is a good solution to consider / test. I haven't seen any problems with the pigment to binder ratio due to the very small amount of oil needed to loosen up the paint. It doesn't take much to do the trick. Adding a few drops of oil to an entire tube of paint doesn't change the ratio very much - less than 0.5% oil added by volume most of the time is sufficient, unless the paint is really stiff. For those stiffer paints a bit of solvent and oil can be an option if you are concerned about adding more than 1/2% by volume of oil. Walnut Oil from my experience slows the hardening of older paints better than Linseed Oil or solvent plus the paint stays wet longer on the palette with the oil. I have some very old W&N Alkyds that were starting to solidify that have stayed just right in syringes for several years now using a very small amount of Walnut Oil. I also prefer the texture of the loosened up paint that I get with Walnut Oil rather than solvent.

I would suggest trying both materials with small samplings so see which you prefer before doing this to a large number of tubes.

Ted Bunker
04-12-2019, 10:08 AM
How does one put paint back into a tube?

There's also the old house painter's trick; put the the reconstituted paint in a clean baby food bottle or those naglene backpackers storage jars with a layer of linseed oil on top to seal out the air ...just remember to pour-off the excess oil before using.

There's nothing that says paint has to be in tubes. As long as no solents were used to revitalize the paint first even a ziploc-type snack bag with the air squeezed out. Linseed and walnut oils are no different than cooking oils to food storage containers. For terps and OMS you might want to test to see if it might disolve the plastic, I know the Spike Lavender does eat into some plastics...

With WMO paints, I don't know if you can submerge then underwater to preserve them like traditional linseed oil paints.

MrsSellers
04-12-2019, 03:05 PM
I put paint back into tubes all the time. I put some on the tip of the palette knife and poke it into the hole. I can squeeze the sides of the tube and it'll usually suck it right in. If that doesn't work, I hold the tube upright in my fist and lightly pound the table so that the tube doesn't hit the table. Works almost every time and saves a ton of paint. It isn't tedious because I don't squeeze out a lot of paint at a time.

sidbledsoe
04-12-2019, 07:44 PM
Some folks don't want to use solvent so that is not an option for them, .

Yes, said "I use" and assumed that it would be a no brainer for the poster and they would know whether to use it or not.

I now know someone who squishes paint back into those little orifices, and does it all the time :lol: .

MarcF
04-12-2019, 09:18 PM
I knew it was something simple like that.