Posted by Martin on April 14, 2013
Sometimes there are long gaps between my painting sessions so unused paints have time separate out with the pigment gradually sinking to the bottom of the bottles leaving a layer of carrier on top. All of which means that I need to give the bottles a vigorous and thorough shake before using them.
I’m fundamentally lazy. So I’m always on the lookout for ideas that will take the effort out of paint shaking. When I buy new bottles, I open them up to insert beads to agitate the paint during shaking, I used to store paints upside down (which I’ve now decided isn’t such a good idea) and I’ve even considered marrying a clamp with a jigsaw as some weird kind of heavy duty power tool paint shaker! However, some time ago, I came across one labour saving paint shaking idea so strange that I never forgot it – even if I didn’t do anything about it for years. The credit for this idea belongs to Martin Stephenson who described the concept of using an ultrasound cleaner to shake paint on his blog The Waving Flag.
I’m not going to elaborate on the theory of how this works because Martin has already covered that. But what I do want to do is describe my experience of trying this. Before I go any further, I want to reassure you that I haven’t taken leave of my senses and purchased an ultrasound cleaner for the sole purpose of shaking paint. That would be mad, wouldn’t it? Yes, er, yes, of course it would…
No, our household has other uses for such a device. I need only mention hard water supplies and blocked shower heads to give you an inkling of our domestic agenda.
Anyway, back to the plot. I asked Martin a number of questions before taking the plunge and he helpfully gave me the benefit of his long experience with this technique. Here are a few of the tips I gleaned from him in answer to my questions:
Q: How many paint bottles (I mostly use Vallejos) can you fit in at a time?
A: The cleaner on my blog will hold 6-8. If doing this you would need to hold them together with an elastic band.
Q: How do prevent the water from soaking the labels off of the bottles?
A: You can’t. New labels survive three of four sessions but be prepared to loose your labels [so I’ve decided that a permanent maker pen will be called for].
Q: Have you tried putting the bottles inside something like zip lock bags to keep them dry?
A: Contact with water is required to transmit the ultrasound waves [meaning that this won’t work].
Q: How long a cycle do you need to achieve a successful outcome?
A: Ah! The piece of string question. Depends on how badly the paint has separated, how old it is and how much has been used. I have left paint in for 1-3, 8 minute sessions.
Q: Do you load the paints in the basket or stand them on the floor of the cleaner?
Q: Presumably you stand them upright, yes?
A: Yes. Doing a couple together helps.
Q: Lastly how far up the side of the bottles do you fill the cleaner with water?
A: There is an ideal level marked in the bath. It’s between half and two thirds of the way up the bottle. I have used less if there isn’t enough paint in the bottle to weigh it down.
Q: Have you got any other tips?
A: Buy one and try it. If you don’t like it your wife will love cleaning her jewellery with it.
My first experiment was an unused bottle of Vallejo Golden Olive (VMC857) paint. It had never been opened or shaken previously so the pigment and carrier were completely separated. I gave it one cycle of 480 seconds in the ultrasound cleaner without seeing much visible reintegration of paint and carrier. Ditto for the second cycle. Then I succumbed to the temptation of just a few seconds manual shaking and was surprised at how quickly and easily the paint was mixing. Encouraged by this, I gave it a third cycle and then squeezed out a blob of paint on to the old ceramic palette to perfect results.
Every good scientist likes to demonstrate that his experimental results are repeatable, so I conducted further trials with unused separated paints to confirm that it works. And, as further evidence for your enjoyment, I kept a video log. When I get a free afternoon, I’ll edit the clips together into something coherent and post it here.
In reality, of course, I’m unlikely to want to shake a solitary completely separated out and unused paint bottle. Apart from anything else, it wouldn’t be very efficient. It’s far more likely that I would want to prepare several bottles of paint at once for a painting session and that they would be in various states of readiness for use. My personal nemesis is a rogue bottle of Vallejo Ochre Brown (VMC856) that never seems to quite be right and always dries slightly shiny or doesn’t have a high enough pigment to carrier ratio to give good coverage. So that little rascal was the next to be subjected to the ultrasound treatment.
After that I moved on to some bulk processing to see how many bottles could be done at once and whether increasing the number of bottles meant that more or longer treatment cycles were required. I found that I could fit a dozen bottles of paint at once in my particular model of ultrasound cleaner and still leave enough space around them for the water to be in contact with as much surface area of the bottles as possible. Spacing them out this way means that the number of treatment cycles does not need to be increased.
In conclusion, using an ultrasound cleaner to shake paint does work. However, if you only need to shake the odd bottle, it’s hardly worth the time and effort. Where it really does come into its own is when you want to shake a whole batch of bottles (for example at the start of a painting session or when you want to restore several paints you haven’t used for a while). In these circumstances, this method is a highly effective labour and time saver. And once you’ve done the first batch you can put more into the machine while you get on with painting. In the past I have considered the Robart Paint Shakers but an ultrasound cleaner beats that option hands down: it’s cheaper, is readily available in the United Kingdom (I got mine for £29.99 from Maplins) and it can shake a whole load of bottles at a time rather time than just one – not to mention being much quieter. Oh, and you can use it for its intended purpose of cleaning things too!
My parting piece of advice if you do decide to go down this route is to remember some basic physics. A lot of energy goes into generation of ultrasound waves in the water and that energy has to go somewhere. Of course, most of it is converted into kinetic energy to shake the paint but, if you do several 480 second cycles in quick succession, you’ll discover that a fair amount gets converrted into heat which will warm up your paints. I think this is an unintended consequence best avoided by leaving short rests between each cycle.
There, now you can all write in and tell me I’ve finally lost my marbles. I don’t care, they were too large to use as agitators in the paint bottles anyway!