Conservation and Restoration of Clear Coatings on Furniture and ...

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The problems arise when these finishes start to break down <strong>and</strong> deteriorate. Not
only do they look bad aesthetically but they stop performing their protective
function, sometimes maybe even damaging the timber as secondary by-products
are produced. To date neither nitro-cellulose nor polyurethanes can be
successfully conserved long term, especially when performing a protective role
during functional use. The only viable solution is to carefully remove the
deteriorated finish, a complex problem in itself.
Polyurethane finish over jarrah which has reacted with over stain to form a two part
hydrogen peroxide bleach. Note the top horizontal has been treated with a stain initially
intended to darken it, the vertical was not treated. See mitre where joints has been taped <strong>of</strong>f
Many <strong>of</strong> the timber surfaces in Parliament House are veneer applied to medium
density fibre board (MDF). The adhesive is urea formaldehyde. Some <strong>of</strong> the
panels have decorative inlay/marquetry which are considered an integral part <strong>of</strong>
the art collection throughout the building. The veneers started life as 0.9 –
0.6mm <strong>and</strong> could be as thin as 0.4mm after they were initially s<strong>and</strong>ed, thus the
timber we are trying to protect is paper thin. This immediately rules out further
s<strong>and</strong>ing or scrapping. Another consideration is the adhesive holding the veneer
to the MDF board <strong>and</strong> the adhesive used in the construction <strong>of</strong> the board itself.
If we use a solvent based system to remove the deteriorated finish, it will be
impossible to prevent it penetrating the thin veneer, thus it needs to dissolve the
finish without affecting the urea formaldehyde adhesive.
Marquetry panel in Marble Foyer designed by
Michael Retter
Finally the choice <strong>of</strong> solvents <strong>and</strong> chemicals also need to comply with the strict Occupational Health <strong>and</strong> Safety (OH
<strong>and</strong> S) regulations <strong>and</strong> environmental restrictions placed on working within Parliament House. As a building which
operates 24hrs a day, 365 days <strong>of</strong> the year it makes for difficult maintenance access.
The removal process will also need to account for the scale <strong>of</strong> Parliament House. All coated timber surfaces will
eventually require their deteriorated coatings removed. Once the finishes have been removed successfully the
dilemma then starts with the second question; ‘With what <strong>and</strong> how should the timber be re-coated?’ If we use the
same or modern equivalent coatings products then in another ten/twenty years we will encounter a similar problem.
Even if we get away with one removal, each successive future removal may cause exponential damage due to the
deterioration <strong>of</strong> the adhesive. Much <strong>of</strong> the timber panelling was coated prior to installation, finished horizontally with
spray equipment. Other timbers were coated in situ prior to the building being opened, thus the strict environmental
guidelines <strong>and</strong> OH <strong>and</strong> S issues were reduced.
Ideally a finish should be employed with the following characteristics;
1. Environmentally friendly to both the person applying <strong>and</strong> the general public
2. Easy to apply, either by h<strong>and</strong> or airless delivery
3. Can be repaired <strong>and</strong> maintained with ease
4. Is durable <strong>and</strong> resilient to wear <strong>and</strong> tear including moisture, cleaning chemicals etc