Rien de Graaf, churchwarden of the Reformed Church of Stavenisse is kind enough to regularly update the Family Fund on the latest developments regarding the restoration of the mausoleum of the Lord of Stavenisse Hieronymus van Tuyll van Serooskerke. Several articles about this fascinating project can already be found on the website.
On February 1, we received the following message from Rien de Graaf:
Here is an email and a link for the photos on the progress until January 31, 2024 of the restoration of the mausoleum.
For quite a while little has happened, just many discussions and several meetings because of the studies and subsequent results.
As you can read below, they will now start the actual work, which will be quite a challenge for the sculptors, now with the new recommendation from TU Delft to flush the parts at a temperature specified by the TU.
Monday 9 October: meeting at TU Delft with Barbara Lubelli, Tobias Snoep, Tim Kemperman, Erik Jan Brans, Silvie Lucas, via streaming Hendrik Jan Tolboom, Rien de Graaf and filmmaker Sander Snoep.
Report by Erik Jan Brans:
Over the past few days I have been in intensive contact with Hendrik about what the results of all the investigations mean and this morning consulted with Barbara and then again with Hendrik.
Barbara warns against “just” flushing the marble. She gives two reasons for this. Firstly, the salt is on the outside and if you put the blocks in the water, the salt can migrate inwards, to the part that is currently under low stress. So you put salt in, which then has to come out again. She is more in favour of compresses that remove the salt superficially. But there is no experience with this and it would have to be tested before it could be applied. That takes a lot of time. Second, she warns against the presence of NaSO4 in the form of Thenardite which, when wet, immediately turns into Mirabilite whose crystals take up more volume due to binding with water and could therefore lead to more damage. Thenardite in particular is relatively abundant in the monument.
However, research has shown that when the stone and water have a temperature higher than 30 degrees Celsius, the conversion of Thenardite to Mirabilite does not take place.
Since the project has already been considerably delayed and working with compresses does deviate a lot from the earlier assumptions, Hendrik and I recommend flushing anyway. There is no time and budget to do an experimental research project. So there will be flushing, but with the following assumptions:
- Only the pieces where damage is now visible will be flushed, starting with a small number of parts. This assumes that the pieces that do not have damage traceable to salts will remain good.
- The blocks to be treated and the water are heated to above 30 degrees before coming into contact with each other and they keep this temperature throughout the rest of the process.
Doing it this way reduces the risks. When treating by flushing other monuments, little to no damage has occurred. However, it is possible that other monuments had a different salt load or composition and it went well there but is risky for this monument.
Although we started late, according to Hendrik, more research has now been done than for any other monument and it may be that other monuments also had a high concentration of Thenardite but that this was not taken into account further or was not known. Hendrik will check whether more research data can be uncovered to see where things were there.
I would ask you to think about this and I look forward to your response.
In the meantime, I have sent data on the front plate to Ben Massop, who has a lot of contact with IBACH and regularly has parts consolidated there. He is looking into it, may be in contact with IBACH and I will report back as soon as I hear from him.
The first step is that we need to start deciding which parts will or will not be flushed and Tobias is making a protocol. I suggest that when that is ready we have another meeting after everyone has had a chance to look at it.
I got a proposal from Tim about the insulation of the back wall and the bottom of the monument. I will look into that and when we are agreed I will send that proposal around for comments.
That’s all for now from Erik Jan Brans.
Wednesday 22 November: meeting in Stavenisse, with Tobias Snoep, Tim Kemperman, Erik Jan Brans, Hendrik Jan Tolboom, filmer Sander Snoep and Rien de Graaf.
- Preparing the floor and outer wall with lead and EPDM.
- Pouring in the rear part of the floor, where there is now only sand.
- Restoring and rebuilding the first layers of black marble.
Report by Erik Jan Brans:
Had a meeting with Tobias and Silvie this morning about the follow-up. We agreed that there will be three actions:
- Tobias is going to draw up a protocol together with Rob Swaab. When that is ready he will send it around and we will discuss it to make it final;
- Determining what needs to be flushed. We suggest that first Tobias in Amsterdam and Tim in Stavenisse respectively put the pieces down so that they can be looked at properly. They can do a first sift, after which Hendrik, Tim and/or Tobias and I will check the pieces and finally “tag” them. That way, pieces that may not need to be rinsed don’t have to be transported unnecessarily. I will circulate a date picker for the session in Stavenisse. Amsterdam seems most convenient to link to the protocol discussion.
- Separately, the process of exploring whether the front plate can be treated at IBACH is ongoing.
The tank for flushing is partly ready. Once it is known what needs to be rinsed, it can be completed, tailored to the pieces to be rinsed.
That’s all for now from Erik Jan Brans.
Monday 11 December: preparing back wall and floor for repositioning tomb.
Thursday 14 December: tools cleared away due to the singing evening on Friday 15 December.
Monday 18 December: Tobias comes from Amsterdam with carrying the two putti and three coats of arms because they do not need to be rinsed, and then Tim together with Tobias loads the parts to be rinsed that were still in the church and brings them safely to Tobias’ workshop in Amsterdam.
Report by Erik Jan Brans:
I called Barbara about the temperature. She indicated that above 35 degrees the conversion of sulphate cannot take place, so such a temperature would be ideal. In contrast, marble cannot withstand higher temperatures and it is difficult to keep both water (still doable) and blocks at such a high temperature. As she put it, the tipping point is not sharp and any temperature heading towards 30 degrees is better than colder ones. She advises against submerging at really low temperatures, say 10 degrees.
It very much depends on what temperature damage occurs, and she mentioned a project where they did a trial that showed that damage occurs at a lower temperature, after which they adapted the installation to a higher one. She recommends doing a trial first, but from what I see in the numbers, the content is variable, so what is true for one block may be different for another.
I suggest doing a small batch of minor blocks first at a temperature of around 25 degrees and monitor carefully what happens. It is important, though, that both block and water have the temperature and not just the water. Therein lies another challenge. Cover the container and put an electric heater in before running pre-heated water in it?
That’s all from Erik Jan Brans.
Week 51:
- Excavate foundation of the tomb to rebuild.
- Tidying up due to Christmas concert on 22 December 2023.
- The tank was delivered to Tobias’ workshop in Amsterdam, so preparations can start there too.
Week 2 to 5:
Continuing with the foundation of the tomb and back wall.
Monday 29 January: had contact with Tobias, who is busy preparing and adjusting the water pumps and the temperature in the room where the tank is located. That is where the parts to be desalinated first go in dry, then they are heated to a temperature of between 25 and 30 degrees and when it is all up to temperature, water of the same temperature can be added very slowly so that the rinsing can actually start. This is expected to be around mid-February.
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