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Pagodas Project Part Three, The Reconstruction

Published by: Hannah Mortell & Ana Vilela
The two base tiers of the twin pagodas
The two base tiers of the twin pagodas

Conservation Assistants Hannah Mortell & Ana Vilela share an exciting update on our ceramics conservation project.

If this is your first encounter with the Pagodas Project, you can find an introduction and the first stage of our work in Introducing the Pagodas Project. A second post explained the process of casting and refining coloured epoxy fills, which you can find in Conservation Continues… Part Two of the Pagodas Project.

This time we will take you through the re-building stage of the restoration or reconstruction of the Pagodas. This was the lengthiest process so far, as we were using several different methods and materials. This was broken down into three main stages:

● Reattachment and consolidation of original porcelain fragments
● Attaching our casted coloured Hxtal fills and refining with Hxtal putty
● Utilising a Polyester resin to refine existing fills of this type and modulate more complex forms

We started by making a tracker of each tier, and separated the work they each needed by these 3 methods. This has helped us to estimate times and plan the work ahead.

The two base tiers of the twin pagodas
The two base tiers of the twin pagodas
Close up of old adhesive on the break edge
Close up of old adhesive on the break edge
Close up of break edge after adhesive removal
Close up of break edge after adhesive removal

Stage 1 – Original Fragments

Upon examining the few original unattached fragments we had, most of them had clear evidence of old adhesives along the break edges from previous failed restoration attempts. This was removed through a combination of mechanical lifting using a scalpel, and applying a cotton wool poultice of Diacetone alcohol to break down any remaining adhesive which may interfere with aligning the fragments as accurately as possible

Close up of break edge after adhesive removal
Close up of break edge after adhesive removal
A fragment wrapped for poulticing
A fragment wrapped for poulticing
The break edge wrapped with a poultice of cotton wool and Diacetone alcohol
The break edge wrapped with a poultice of cotton wool and Diacetone alcohol
The fragments laid out in ‘sticking order’ This is vital to get the best fit
The fragments laid out in ‘sticking order’ This is vital to get the best fit

We then held the pieces together in place using low-tack tape to determine the proper order to adhere them in.

The fragments were given numbers based on this order and we began to reattach them to the ceramic body.

The fragments laid out in ‘sticking order’ This is vital to get the best fit
The fragments laid out in ‘sticking order’ This is vital to get the best fit
Holding the fragments together using low-tack tape while curing
Holding the fragments together using low-tack tape while curing
A couple fragments before and after being placed onto the balustrade ready to consolidate
A couple fragments before and after being placed onto the balustrade ready to consolidate

We decided to attempt to reconstruct the fragments using a reversible adhesive; Paraloid B72 (20% in 3:1 Acetone: IMS w/v)

However we found this was not strong enough due to the complexity of the break edges along many small points of contact. We decided instead to only apply Paraloid B72 as a barrier between our casted Hxtal fills and the original porcelain to maintain some reversibility in the future should they need to be removed.

Hopefully the original fragments will unlikely be removed in the future and so we could use a stronger option. We used the same Hxtal epoxy which made up our casted fills, in its non-bulked original form – a crystal clear and non-yellowing resin – a well-known stable material often used in ceramics conservation.

A couple fragments before and after being placed onto the balustrade ready to consolidate
A couple fragments before and after being placed onto the balustrade ready to consolidate
A couple fragments before and after being placed onto the balustrade ready to consolidate
A couple fragments before and after being placed onto the balustrade ready to consolidate
Using low-tack tape to support fragments while they cure
Using low-tack tape to support fragments while they cure

We carefully applied it with a soft, thin brush along the breakage line making use of the capillarity and cleaned any excess.

The fragments were securely held in place with tape to keep them from dislodging and left for a week to cure.

Using low-tack tape to support fragments while they cure
Using low-tack tape to support fragments while they cure
Large holes where column cast will be attached
Large holes where column cast will be attached

Stage 2 – Attaching and refining our casted Hxtal fills

The next stage was the reconstruction with our Hxtal epoxy resin casts and localised infills with Hxtal putty.

Again, a protective layer of Paraloid B72 at 20% was used to protect the original ceramic body. We also bulked this with glass micro balloons to fill any holes in the ceramic body and prevent the resin from permeating too deeply into the ceramic.

On larger and irregular surface areas we used Paraloid B72 (40% in methoxypropanol w/v), this higher viscosity allowed us to level out the contact area for the casts.

Large holes where column cast will be attached
Large holes where column cast will be attached
Holes filled using Paraloid B72 bulked with glass microballoons
Holes filled using Paraloid B72 bulked with glass microballoons
Levelling contact areas for casts with high viscosity Paraloid B72 with a plasticine frame
Levelling contact areas for casts with high viscosity Paraloid B72 with a plasticine frame
Irregular surface area Smoothed out using Paraloid B72 & Bondina (before)
Irregular surface area Smoothed out using Paraloid B72 & Bondina (before)

Finally, we applied unwoven tissue – Bondina – as an extra barrier layer. After curing time, it was time for the reconstruction itself.

Irregular surface area Smoothed out using Paraloid B72 & Bondina (before)
Irregular surface area Smoothed out using Paraloid B72 & Bondina (before)
Irregular surface area Smoothed out using Paraloid B72 & Bondina (after)
Irregular surface area Smoothed out using Paraloid B72 & Bondina (after)
Using Bondina textile as a barrier
Using Bondina textile as a barrier
Column fully filled after using Bondina as a barrier to prevent Hxtal epoxy from permeating too deep into the ceramic body
Column fully filled after using Bondina as a barrier to prevent Hxtal epoxy from permeating too deep into the ceramic body
One small cast in place
One small cast in place

The casts range from centimetres in size to complete balustrades or columns.

One of the base tiers had its balustrades almost entirely reconstructed by casts.

In some cases, the cast itself was used as support to hold the fragment in place during the curing. The reconstruction of this tier was complex due to the number and size of elements to incorporate and align cohesively.

We started by incorporating the casts one by one and to ascertain the correct alignment and heights for the balustrades. For the first step we recreated the reconstruction using tape, plasticine, and wooden sticks to keep the casts in place.

One small cast in place
One small cast in place
Ana inserting small cast
Ana inserting small cast
Large reconstructed top area
Large reconstructed top area
Cast elements hold in place
Cast elements hold in place
Cast elements hold in place
Cast elements hold in place
A sequence of the different stages of casts and fragments reconstruction
A sequence of the different stages of casts and fragments reconstruction
Using a spirit level to ensure correct alignment of casts
Using a spirit level to ensure correct alignment of casts
Putty infill with a syringe under one of the cast columns as a first step to promote stability for the remainder of the reconstruction cast elements.
Putty infill with a syringe under one of the cast columns as a first step to promote stability for the remainder of the reconstruction cast elements.

Once the optimal reconstruction was achieved, Hxtal putty was introduced in different structural points and left to cure.

This has reduced the amount of tape needed to secure casts in place increasing visibility, workability and strengthened the stability of the casts during this process.

We also made use of the slow-curing characteristic of the epoxy resin by using heat to slightly mould the casts to the ceramic body by either immersing the casts in hot water pre-adhesion or using a blow dryer after adhesion and curing.

After this first cure, we infilled all the remaining gaps that needed free handed reconstruction with Hxtal putty. We smoothened the resin surface using an array of spatulas, syringes, small brushes, acetone and melinex film.

Putty infill with a syringe under one of the cast columns as a first step to promote stability for the remainder of the reconstruction cast elements.
Putty infill with a syringe under one of the cast columns as a first step to promote stability for the remainder of the reconstruction cast elements.
Close up of a small loss in the balustrade, and a large crack
Close up of a small loss in the balustrade, and a large crack
Modulation using Hxtal epoxy putty to create small missing pieces of the balustrade
Modulation using Hxtal epoxy putty to create small missing pieces of the balustrade
The join between cast and original before gap filling with Hxtal epoxy putty
The join between cast and original before gap filling with Hxtal epoxy putty
The join between cast and original after gap filling with Hxtal epoxy putty, and before refinement
Casted piece attached and gaps filled using Hxtal epoxy putty, before refinement
Casted piece attached and gaps filled using Hxtal epoxy putty, before refinement
Hannah adding Hxtal epoxy putty to ceramic using a dental tool
Hannah adding Hxtal epoxy putty to ceramic using a dental tool
Cast attached and filled but too thin
Cast attached and filled but too thin
Cast widened using epoxy putty bulked with large amount of fumed silica to form the ‘frame’
Cast widened using epoxy putty bulked with large amount of fumed silica to form the ‘frame’
Facet made up of fragments as shown earlier, now all gaps filled using small cast pieces as well as fills with epoxy putty
Facet made up of fragments as shown earlier, now all gaps filled using small cast pieces as well as fills with epoxy putty
Bernarda cleaning epoxy putty residues before the curing process
Bernarda cleaning epoxy putty residues before the curing process
Refining the Hxtal putty using an electric nail file and wet/dry glasspaper
Refining the Hxtal putty using an electric nail file and wet/dry glasspaper

After the final cure we proceeded with the refining.

Refining is a very important and meticulous process to achieve a homogenous texture throughout and to visually blend the casts into the porcelain. Refining is the last preparation to perfect what will be the ground layer to the next stage: the inpainting.

We used electric nail filers with different size attachments which permitted us to refine in great detail. A final finishing was done with glass paper and micro-mesh of increasing grades to achieve a smooth shiny finish to mimic the ceramic body.

Refining the Hxtal putty using an electric nail file and wet/dry glasspaper
Refining the Hxtal putty using an electric nail file and wet/dry glasspaper
Refining the Hxtal putty using an electric nail file and wet/dry glasspaper
Refining the Hxtal putty using an electric nail file and wet/dry glasspaper
Polyester resin balustrade cast from the early 2000’s restoration, before refinement
Polyester resin balustrade cast from the early 2000’s restoration, before refinement

Stage 3 – Polyester resin refinement & modulation

On a number of tiers of the pagodas, some polyester resin casts had been made and attached by a previous conservator.

This material has been replaced in ceramics conservation over time by clear epoxies such as Hxtal, but at the time was a viable and simple to work with option.

Some of these casts needed some refinement so we decided the best course of action was to treat like with like, and refine and add material using a similar polyester resin product.

Polyester resin balustrade cast from the early 2000’s restoration, before refinement
Polyester resin balustrade cast from the early 2000’s restoration, before refinement
Polyester resin balustrade cast from the early 2000’s restoration, with added polyester resin to refine the finish, seen here in a lighter colour
Polyester resin balustrade cast from the early 2000’s restoration, with added polyester resin to refine the finish, seen here in a lighter colour

This was mostly prominent in some casts of the balustrades, some tips to the roof tiers and the small dragons which sit on the finials.

The product we used cured much faster than the Hxtal epoxy, it only took 30 minutes or less to cure as opposed to one week. It was a much faster refinement process and could be done in one sitting, which was a huge time advantage.

Polyester resin balustrade cast from the early 2000’s restoration, with added polyester resin to refine the finish, seen here in a lighter colour
Polyester resin balustrade cast from the early 2000’s restoration, with added polyester resin to refine the finish, seen here in a lighter colour
A large cast made from Polyester resin in the early 2000’s, all the roof tips added to and refined by us
A large cast made from Polyester resin in the early 2000’s, all the roof tips added to and refined by us
A close up of some of the tips as material was added to be refined. The change in colour shows the line between the older material and the newer additions
The different colour on the tips shows the line between the older material & the newer additions
A close up of a polyester resin cast next to some Hxtal epoxy tips we attached to the original - these two different materials had to match in form so it becomes less after inpainting
Hxtal epoxy tips next to polyester resin cast which needed additional material to achieve a harmonious form
Showing the same piece after refinement with an electric nail file and glass-paper
Showing the same piece after refinement with an electric nail file and glass-paper
Perfecting the scalloped edges of the roof tips using an electric nail file
Perfecting the scalloped edges of the roof tips using an electric nail file

We modulated the polyester resin into proper shape using spatulas and brushes, then once cured we could carve and file into the resin to refine the shapes.

This reconstruction and refinement phase of the Pagoda project has been the longest yet. Attention to detail where our added material meets the original porcelain surface is very important and will affect the finish once layers of paint are added on top.

The next stage is the inpainting, which we have already begun!

We are nearing the end of this exciting project, and our next post will explore the intricacies of imitating the intricate detail work which went into crafting these Pagodas when they were made.

Here is a sneak peek of our inpainting and colour-matching set up, we look forward to showing you more soon.

Perfecting the scalloped edges of the roof tips using an electric nail file
Perfecting the scalloped edges of the roof tips using an electric nail file
Inpainting and colour-matching practice
Inpainting and colour-matching practice