Case Study 4: Physical conservation vs digitisation for preservation


Case Study 4 investigated different methods to preserve print monographs which are currently kept on the open shelves. In particular, we wanted to compare the long term costings of physical conservation, versus digital preservation. The results were striking, and showed clearly that choosing the least expensive preservation option in the first instance can lead to far greater costs over time. The following is an overview - you can download the full internal report (PDF) here.


The Process

The process can be simplified to the following:

Diagram showing, in sequence:
Choose and assess a sample; Calculate costs to physically conserve the sample; Calculate costs to physically conserve the sample
; Obtain quotes to digitally preserve the sample through outsourcing; Calculate the long-term storage costs, both physical and digital; Produce & cost six 'preservation pathways' for different approaches to preserve print monographs over varying periods of time


The first outcome to develop from this case study was the result of the Condition and Usability survey, undertaken on the French M sample. Strikingly, only 12 of the 200 item sample could be considered to be in good condition and not at risk at this time. 68 were in fair condition. Almost half, 99 items in total, were in poor condition and needed urgent conservation, and the remaining 21 were at severe risk and needed immediate action. More details of this assessment and the value of surveying your collection, can be found in the downloadable document Assessing a Collection for Condition and Usability (.PDF).

The next outcomes were the costs of the various different preservation pathways. For each pathway, exact costings were produced by calculating the amount of time required for each action, and costing it at exactly half-way up the Leeds University pay-grade at which the person undertaking the action would be paid (costings included pensions, National Insurance contributions etc, rather than just the basic salary). These were combined with the quotes for external digitisation work where appropriate.

As a result of these calculations, the costings for undertaking preservation in each of the six ways were as follows:

Table showing the initial cost of each preservation pathway. Specifically:

[Information and advice on approaching external providers of digitisation can be found in the downloadable document Out-sourcing Digitisation (.PDF).]

Long term storage costs needed to be factored in for the figures to have real value. We calculated storage using Neilsen and Courant’s On the cost of keeping a book – the most contemporary and comprehensive paper on the subject. You can read the article in PDF format here; it starts on page 81.

The graph below shows how one preservation pathway can begin as more efficient than another, but this can change over time due to the differences in storage costs. Sympathetic digitisation, both in-house and outsourced, is of course the most expensive method, because it requires a significant initial outlay to digitally preserve the items, and then because the paper copies are kept they also need to be conserved, so both physical and digital storage costs apply. For the calculations below, it is assumed that in order to keep the 200 item sample on the shelves, comprehensive conservation would have to be undertaken every 50 years. Costings for Primary Conservation end after 50 years, because by that time a large percentage of the sample would be unusable or destroyed due to not having undergone de-acidification.

It is worth stating explicitly that due to the numerous variables involved, these costs are not intended to be actual predictions of actual monies spent over a 1 to 250 year period. These are intended to be comparative costings that illustrate the trends of the different preservation pathways, over time.

NB: Costings for outsourced digitisation use the cheapest quotes we received. Please note also that the X axis of the graph (number of years) is not to scale.

graph showing the long-term costs of the 6 preservation pathways

The results above clearly indicate that in-house destructive digitisation is the most efficient long term method, despite the considerably higher initial investment than is required for physical conservation. By the time 50 years has elapsed the total accumulative costs are already cheaper for destructive digitisation; thereafter physical conservation becomes more and more expensive than the digitisation due to the storage costs incurred, and the need for repeated conservation actions.


1. For paper materials of no intrinsic value, replace them with digital surrogates created in-house
Our findings clearly show that in-house digitisation, in which the materials are not returned to the shelves afterwards, is the most efficient way of storing collections long term. Storing digital items is so much cheaper than storing physical items, that even with a far greater initial cost they become ‘cheaper’ within 50 years. This is the main recommendation that arises from this Case Study.

2. Factor in carbon costs to the overall figures
It is predicted that carbon costs will become more and more important, therefore the environmental impact of physical conservation (and storage) versus digital preservation (and storage) should also be considered in projects like these. 

3. Bid for a Conservator’s time on future projects
LIFE-SHARE would recommend that future projects of this nature invest in the time and resources of a conservator as part of the funding bid. The National Archive advocate doing this for any digitisation project, in order to ensure that the monographs can be assessed and if necessary stabilised, before digital capture takes place. Although this particular case study didn’t result in any large scale digitisation, we still required considerable time and attention from the Library’s Conservation Officer who was not initially part of the project team. Had a conservator’s time been ‘bought’ as part of the bid, this would have been simpler to achieve and we could have sampled a larger part of the French collection to assess for condition and usability.