Modular Cleaning (Science Alert!)

Bottles of Modular Cleaning solutions. E Jowett Conservation

I spent a week in London learning about a new (to me) system for cleaning paintings called the Modular Cleaning Program, through lectures and lab/studio time. The leader of the course was Chris Stavroudis, an independent conservator from Hollywood who has been working on complex cleaning problems with the conservation team at The Getty for many years. Thirty conservators at different stages in their careers, mainly from the UK but also from Europe, the US and Australia, gathered to learn something new.

What is the MCP?

It’s called the Modular Cleaning Program (MCP) because from a kit of stock solutions you can mix and match to test lots of different solutions in a short time. Though the recipe for the tests may change, there are always five parts to the recipe, which helps keep things simple. The five elements are water, buffer, chelator, surfactant and gel. In any small test you use 1ml of each component and that ensures that everything is at the correct concentration. Using the accompanying computer software, which will automatically adjust all of the elements if you make a change to one, even an art historian like me can be confident that I’ve not mixed up something I shouldn’t have. That’s not to say that the computer program does the thinking, just that it keeps track of all of the different elements for you.

Here comes the science bit

The lectures were patiently delivered to a room largely full of arts people, rather than scientists, trying their best to understand. As conservators, we could see the applications of the science even if it was a struggle to get a handle on the molecular workings. The range of experience among the people in the workshop was really useful during discussion times, as people’s questions and comments helped everyone get more out of the workshop.

The concept of solubility parameters (the intermolecular forces that hold things together, determining the kind of forces needed to split them up) and that ‘like dissolves like’ is central to all cleaning. While this is something I was taught during my training, Chris Stavroudis and his colleagues have really been digging down into what goes on inside layers of dirt, varnish and paint, and even what’s going on within each of those things and formulating solutions to address each one.

It starts from looking at what we already use safely (for the painting) and effectively and tries to improve it (the computer program button for trying the improve the solution says ‘Yes but modify’). So, for example, a lot of us use spit for removing surface dirt (this did get a bit contentious during the week as some people think it’s too disgusting). What’s good about spit is that it’s slightly viscous, meaning it doesn’t go everywhere, and it’s full of enzymes that can target certain components in the dirt, and it comes free and ready buffered. The less good things are that it’s a bit icky, it’s inconsistent (depending on whether you had a heavy night on the gin or pineapple at lunch) and you need to clear it from the surface with water, which some surfaces don’t like. Then there’s water. It can be deionised, distilled, carbonated or from the tap. For a long time I assumed it was best to use deionised water, as it seems more scientific and careful somehow (as you’ve gathered I’m not a natural scientist). However, its lack of ions means it’s hungry and can strip ions from a surface indiscriminately, which means its sometimes better to use tap. In the MCP there is a selection of adjusted waters, which means they are pH buffered and conductivity controlled (conductivity is how you measure the ions in the water) so that you can use the right one for the job.

When it comes to varnish removal, I and many or even most conservators use free solvents, that is, liquids in a bottle applied to the surface with a swab and evaporate willy -nilly into the air and into your lungs. While this is perfectly fine for the paintings (so long as you’ve tested for safety beforehand) it’s not the healthiest of occupations. The MCP allows for formulating aqueous gels, emulsions and micro-emulsions that carry smaller amounts of solvent or resin soaps instead and stop the solvent from evaporating so readily. An aim of the MCP is to find something that is better for the conservator and better for the environment. There is an added element of controllability, as each distinct layer of grime and oxidation is targeted by a specific solution and removed to leave a displayable surface. This way the client and conservator can choose together where to stop for the best result. Of course, not all paintings play by the rules and this kind of layer unpacking won’t always be possible.

Getting stuck in

Measuring pH E Jowett Conservation
Measuring the pH of a solution

Making the solutions

Lab time had a bit of a Breaking Bad feel to it. We split into groups and given a recipe to follow, though we first had to multiply everything by 30 to ensure there would be enough for everyone to take home. I’ve never seen so many bottles of chemicals. Many of the solutions required making up to a specific pH, which in practice meant a lot of grown-ups staring intently at pH meters and getting very excited by seeing the numbers change. The excitement came as carefully prepared solutions suddenly went shooting out of a buffer zone (something, according to the lectures, to do with de-protonation and fat kids on see-saws) and had to be salvaged by rebalancing the components. By day 3 or 4 we developed a pretty good production line and knew when to go carefully and when we could be more relaxed.

MCP Workshop E Jowett Conservation
Bottling up one of our solutions.

Testing the program

When we weren’t cooking up litres of stock solutions we worked in groups on some sample paintings. These paintings are the kind of thing that many institution studios have in drawers, that someone has had a go at in the past and given up on. The one my team were working on had been partially cleaned, meaning that there was still some varnish on in some places, but other areas had been over cleaned, damaging the paint underneath. There isn’t anything quite like trying something out on authentic dirt and varnish layers, especially when there’s no pressure to get it right! My friend Mike, who trained at the same time as me in Northumbria and now works at the Whitworth Gallery, took a video of me cleaning our group’s painting with one of our concoctions.

MCP workshop team E Jowett Conservation
My team mates using the MCP software to find a way to clean this painting.

Another group had a painting that was really difficult to clean. Some of the mixtures had no effect and others were cleaning it but also taking off the top layer of paint too. By trying different solutions and methods of application there was a glimmer of hope for that painting by the end of the week, but the clock had run down.

Bringing it back

Now that I am back with my large and heavy box full of solutions and my head full of new ideas, I’m excited to see when my first opportunity will be to use it. I’m excited about adjusted water. Now, rather than choosing between just deionised water or tap water I am able to test pH buffered and conductivity controlled waters that will evaporate more completely from the surface.

My mind has been brought back to the importance of working out the constituents of the stuff that I’m trying to remove, and using that information to tackle and target it. It’s so good to have more tricks up my sleeve when dealing with more complex cleans, especially when that means using less harmful substances. I don’t suppose I’ll abandon spit, but there are other things that I’ll probably phase out.

I’ve also been reminded of what a funny, clever bunch of people work in paintings conservation around the country. The enthusiasm, enjoyment of the job and keenness to accrue new skills is just as sharp in those who have been in the business for 30+ years as it is for those who have just graduated.

 

 

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