Fire Extinguishers: Demystified

Types of Fires and Fire Extinguishers

There are four main types of fire:

  1. Class A: Ordinary Combustibles, such as wood, paper, and cloth
  2. Class B: Flammable Liquids and Gases, such as oil, gasoline, propane, and paints
  3. Class C: Live Electricity, includes electrical equipment
  4. Class D: Combustible Metals and Metal Alloys, such as magnesium, titanium, sodium and potassium (this type of not very common)

Every extinguisher is labelled to indicate which types of fires the extinguisher is effective against, using the fire type classification system. For example, a fire extinguisher labelled ABC is effective against class A, B and C fires. There may also be numbers in front of the class designations. These numbers indicate the comparative effectiveness of the extinguisher to combat the specified type of fire. Higher numbers indicate higher levels of effectiveness. For example, a fire extinguisher labelled 1-A:10-B:C is less effective at combatting class A fires than a fire extinguisher labelled 2-A:10-B:C. Class C does not have a number classification.

Conduct a risk assessment to identify your fire hazards and ensure you purchase fire extinguishers that are effective against potential fires at your archives, be it class A, B, C or D or a combination of fire types.

Extinguishing Agents

There are different extinguishing agents for each class of fires:

  1. Water extinguishers: Class A fires only. Never use water on class B, C or D fires. Water may cause damage to archival records and electronics.
  2. Dry chemical extinguishers (powder with pressurized nitrogen): Combination of class A, B, and C fires (check label of extinguisher). The residue may cause damage to archival records and electronics.
  3. Chemical foam (aqueous film forming foam): Class A and B fires only. The residue may cause damage to archival records and electronics.
  4. Compressed gas extinguishers (pressurized CO2 or halon): Class B and C fires only. This does not leave a harmful residue, but is not effective on class A fires.

It is extremely important to know the type of fire extinguisher you are using and what type of fire you are dealing with. Using the wrong extinguishing agent may feed the fire instead of suppressing it. If you do not know the type of fire, the type of extinguisher or how to use it, evacuate the building safely and call the fire department.

It is important to research the effects of these extinguishing agents on the media types and equipment found in your facility. Some of ASA’s institutional members have installed CleanguardTM Clean Agent Extinguishers at their facilities**. CleanguardTM uses DuPontTM FE-36TM as the extinguishing agent. The producers claim it is electrically nonconductive, low in toxicity, and environmentally friendly, in addition to being an effective fire suppressor. Conduct research on all types of extinguishing agents and their effects on your collection and equipment prior to purchasing any products.

** The ASA does not endorse the use of any particular brand of fire extinguisher.

Where to House Fire Extinguishers

It is recommended to house fire extinguishers near potential hazards identified in your risk assessment. They should be housed visibly near an exit. It is recommended to have your back to an exit while extinguishing fires in order to have a clear escape route. For example, a staff kitchen is usually identified as a fire risk in a risk assessment. If possible, store the fire extinguisher on the wall adjacent to the door to the kitchen.


Fire extinguisher training is extremely important. Do not attempt to operate a fire extinguisher without the proper training. Consider offering training to your staff as part of your disaster preparedness training. This may be offered through your Occupational Health and Safety Department or your local Fire Department.

Here is an acronym to help you remember how to use an extinguisher once you have received training:

Pull the fire extinguisher’s safety pin.

Aim at the source or base of the flames. It is recommended to stand at least 6 feet away from the flames; however, the fire extinguisher should indicate how far away you should stand from the flame.

Squeeze the handle or trigger.

Sweep the source or the base of the flames until the extinguisher is empty.

After Using a Fire Extinguisher

If you use a fire extinguisher, refill or replace it immediately. Extinguishers with metal valves can be refilled and extinguishers with plastic valves cannot be refilled and should be discarded and replaced.

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Could it be Cellulose Nitrate?

When completing a collection survey, you may come across negatives and be uncertain of whether or not they should be frozen. There are many ways to determine what the base of the negatives could be, including various chemical tests and burning tests. Purchasing chemicals can be expensive, and dangerous to house and dispose of. While burning tests work, they require sacrificing a piece of the negative and lighting a fire.

A safe, reusable, environmentally friendly, and inexpensive method of analyzing negatives is to look at one between two linear polarizers. Linear polarizers are a type of grey, transparent film used in photography as a camera filter. When purchasing linear polarizer film, it is important not to order circular polarizer film as it will not perform the same way.

How to use it:

  1. Cut two pieces of film from a sheet.
  2. Create a frame for both pieces using acid-free mat board. This will help protect the film from abrasions and fingerprints.
  3. Sandwich the negative between the two pieces of matted film and hold up to natural light.
  4. Rotate one piece of matted film.

What to look for: When the one of the matted film pieces is rotated you will see one of two things: The negative and film will both appear to darken, or colours will be seen, called birefringence.

Birefringence. Photo credit: Dave See

Birefringence. Photo credit: Dave See

Birefringence will only be encountered when looking at a polyester negative. If you see the film darken, the negative is either nitrate or acetate. Polyester negatives are relatively stable and do not need to be frozen. Cellulose nitrate and cellulose acetate negatives should be frozen as they off-gas nitrous oxide and nitrogen dioxide or acetic acid, and they rapidly degrade. Cellulose nitrate is also a fire hazard because it can auto-ignite, and the fire cannot be put out.

To further identify between cellulose nitrate and cellulose acetate, you can consult the Northeast Document Conservation Center’s guide to visually identifying negatives:

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What to do in a Zombie Attack**

Your disaster plan includes instructions on how to deal with different disasters, such as fires, floods, and theft, among others. Few disaster plans cover what should be done in the event of a zombie attack. Zombies are undead creatures that eat human flesh. The virus is passed on through a bite or scratch from an infected individual. The Lead Team believes it is important to prepare for all types of disasters, so here are a few tips on handling a zombie attack:

  1. Remain calm.
  2. Call your local authorities, if time permits. Note that if this is a wide spread epidemic, the authorities may not respond to your call.
  3. Barricade all staff and visitors in a secure space, such as your vault.
  4. Ensure all staff and visitors in the secure space have not been infected.
  5. Remain quiet.
  6. Do not use archival records or artefacts to defend yourself against zombies, if possible.
  7. Consider keeping blunt instruments in your disaster kit to protect your staff and visitors from a zombie attack.
  8. Include self-defence training as part of your institutional disaster training.
Photo credit: Stephen Dann

Photo credit: Stephen Dann

Disaster preparedness is key to protecting staff, researchers and our collections from these types of attacks!

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**This post is all in good fun. Happy Halloween!

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Good Work by the Flood Advisory Programme’s Lead Team

South Peace Regional Archives gratefully acknowledges the benefit received from the ASA Flood Advisory Programme, through Lead Archivist Amanda Oliver and Lead Conservator Emily Turgeon-Brunet.

SPRA is located in the Grande Prairie Museum, which sits on the banks of Bear Creek, a potential flood plain. Although the creek has never overflowed in our time, we have suffered a flood from above, caused by our flat roof.

We knew that our Disaster Preparedness Plan needed to be revised and more supplies purchased. We had a Disaster Response Kit of sorts, but it was basically a list of all the materials we would need in case of an emergency, and where they were stored.

Amanda and Emily’s report through the Flood Advisory Programme makes it so easy to address our weaknesses.  They laid out an easy to follow plan and gave us the conservation materials needed to do it correctly. This included a bin containing the things we were missing, such as sock barriers, Hollytex sheets, protective coveralls, and hard hats. It is very comforting to have all the supplies in one bin, which is now stored in our isolation room right off the receiving bay. Archives staff were also very excited about winning the fume hood used for the Flood Advisory Programme! Until now, when we needed to use toxic chemicals to clean film or when we wanted to remove mould from paper records, we have had to wait for a quiet, warm day in summer so we can work on them in the ventilated outdoors. This fume hood will allow us to work safely with cleaners and mouldy records as required. For the moment, it resides on a back table in the Archives Processing Room, but we are looking forward to the day when it is up and running.

Thank You, Archives Society of Alberta, for your practical support of archives across Alberta.

Sincere Regards,

Mary Nutting, Executive Director

South Peace Regional Archives

And the Oscar Goes to… (Behind the Scenes of our How-to Videos)

When the Lead Team was researching types of resources to share on our website, we realized fairly quickly a lack of video resources about disaster recovery available online. Although there are some great videos out there, the videos were hard to find and the videos themselves were quite long. The available video resources were not appropriate if an archivist needed salvage information quickly. We decided it would be beneficial to create how-to videos for the ASA website that were concise and easy to find.

Emily Turgeon-Brunet preparing to film a video about mould removal.

Emily Turgeon-Brunet preparing to film a video about mould removal.

Throughout the fall of 2014, the Lead Team decided on six topics for the videos and wrote scripts for these topics. We filmed three of the videos ourselves during the winter of 2015. Although the content of the videos was strong, we felt the poor production value distracted from the content. In the spring of 2015, the Lead Team interviewed four local video production companies and hired Back Road Productions ( to help us create our videos. Dylan Howard worked closely with us to ensure that our content was presented in an interesting and visually appealing way. He was very patient with us and his attention to detail was much appreciated.

Amanda Oliver preparing to film the video about packing wet records.

Amanda Oliver preparing to film the video about packing wet records.

We had some difficulty securing an appropriate filming location for the required time period. Fortunately, the Edmonton Public Schools Archives and Museum ( was able to accommodate us. The archives and museum is located within the oldest standing brick school in Alberta, which was designated as a Provincial Historic Resource in 1976. It is a beautiful building and was a stunning and appropriate backdrop for our videos. Thank you to the Edmonton Public Schools Archives and Museum staff for your time, space and patience!

We spent a lot of time selecting and placing props in the background of our videos, especially deciding on what to write on the chalkboard. Do you know what the chemical equation on the chalkboard is for? Let us know in the comments!


Emily Turgeon-Brunet filming a close up shot.

We filmed the videos over three days in June 2015. Topics included: handling wet records, packing wet records, drying wet records, flattening and humidifying, mould removal and encapsulation. The filming process was quite long and stressful; however, the team at Back Road Productions was very patient and made us feel comfortable throughout the filming process. They did an excellent job transforming the footage into the videos available on our website!

Amanda Oliver wrapping bound material in wax paper for the packing wet records video.

Amanda Oliver wrapping bound material in wax paper for the packing wet records video.

The videos are available on our website: Let us know what you think of the videos in the comments! Please be kind to us while viewing the videos – remember that we are not actors, but an archivist and a conservator! We were definitely out of our element being on camera; however, we hope the finished product will benefit the greater documentary heritage community.

Thank you again to Back Road Productions and the Edmonton Public Schools Archives and Museums for helping us create these resources.

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Introducing our New Video Resources!

For Archives Week 2015, the Lead Team has created six video resources for the Flood Advisory Programme’s webpage. These videos are intended to be concise resources which demonstrate basic salvage techniques to help archivists during an emergency.

Handling Wet Paper

Watch this video to learn how to handle wet paper without tearing it.

Packing Wet Records

Watch this video to learn how to pack wet records.

Drying Wet Records

Watch this video to learn a variety of ways to dry wet paper.

Humidifying and Flattening Paper Records  

Watch this video to learn two techniques to humidify and flatten records.

Mould Removal

Watch this video to learn how to safely remove mould.


Watch this video to learn how to encapsulate records using Mylar.

The videos were filmed on location at the Edmonton Public Schools Archives and Museum. Funding for the videos was provided by Alberta Culture and Tourism. We hope you find these resources helpful. Happy Archives Week!

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‘Minor’ Disasters Can Cause Major Damage

Does your disaster plan include ‘minor’ disasters, such as accidental damage and leaks? Do you think you only need to prepare for major catastrophes? Seemingly small incidents can cause significant damage to your collection. Recently, an unnoticed drip from a HVAC system at the City of Edmonton Archives caused significant water damage to and mould growth on archival records, boxes and shelving units. Approximately forty boxes were affected by this issue and all affected boxes were bagged to contain the mould. The material was triaged by City of Edmonton Archives’ archivist Tim O’Grady while the boxes were being bagged. The sorting was based on degree of wetness, degree of mould growth and if the material had been previously reproduced.


Example of mould found on bound archival item and box. Photo credit: City of Edmonton Archives.

After everything had been bagged, we* began drying the material. Each bag was opened and each box was examined. Most of the paper records were damp and not saturated with water. Items were removed from their folders and placed between blotting paper to dry. The blotting paper stacks were rotated and cockled blotting paper was changed. The majority of mould found on the paper records was found in the folder or box and minimal mould was found directly on the paper. Documentation was extremely important during the drying process, especially since the boxes and folders needed to be discarded. We had a scribe take notes on the original box and folder numbers as well as the file’s current location. This information was also written on the blotting paper where the records were placed to dry. Original order was maintained throughout the drying process.

Jayme Vallieres and Amanda Oliver removing the textblock from the binding. Photo credit: City of Edmonton Archives.

Jayme Vallieres and Amanda Oliver removing a textblock from its binding. Photo credit: City of Edmonton Archives.

Unfortunately, the bound material was most negatively affected by the leak. Mould was present in the box and on the front and back covers. Some items had mould on the endpapers, but most items did not have mould within the textblock. Items covered in mould were handled in an isolated space away from the collection. Jayme Vallieres, ASA’s contract paper conservator, removed the textblock from the binding of all affected bound items in the archives’ loading dock. Every item was photographed before the front covers, back covers, and some endpapers were discarded. The bound items were then dried upright using supports found on site. One large bound item required interleaving with absorbent paper (newsprint) to promote the drying process. The newsprint was changed multiple times as it became saturated.

Bound material drying upright. Photo credit: City of Edmonton Archives

Bound material drying upright. Photo credit: City of Edmonton Archives

The shelving units were bleached to clean mould from the shelves. Fans and dehumidifiers were placed in the room to help promote drying. The material is currently drying nicely. The City of Edmonton Archives is now in the process of hiring a contract conservator to surface clean all of the records to remove the mould. Cold storage is recommended until then to deter future mould growth. All of the material is salvageable.

This is a reminder to inspect your vaults on a regular basis and examine any potential water sources, such as pipes and HVAC systems, for leaks. Mould growth can occur within 48 hours of contact with moisture so check your vaults often. You may also wish to incorporate your integrated pest management system into these checks by looking for any signs of pests. In addition, it is extremely important to have disaster supplies on site in case of an emergency. Thankfully, ASA and the City of Edmonton Archives had blotting paper on hand to dry the affected material. No disaster is too small to prepare for!

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*City of Edmonton Archives staff and ASA’s Amanda Oliver and Jayme Vallieres

Project by the Numbers (2)

ASA’s Flood Advisory Programme is one year into its two year project! This is some of the work we have completed so far:

  • Travelled 30 386 kilometres
  • Treated 2114 items
  • Wrote 34 condition reports
  • Conducted 27 site assessments
  • Created 27 work plans
  • Placed 22 supply orders
  • Posted 21 blog entries
  • Created 7 online resources (ASA’s Flood Assistance Page)
  • Filmed 6 how-to videos
  • Hired 4 contractors to complete work at heavily impacted sites
  • Taught 4 sessions at the Archives Institute
  • Wrote 4 board reports
  • Wrote 4 newsletter articles
  • Attended 4 conferences
  • Wrote 2 disaster plans

We are looking forward to the next 18 months!

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Recipe: Baking Mat Board

It is necessary to house select records below -5°C to slow the rate of degradation. When purchasing a freezer, ensure that it is frost-free and that there is a digital monitor on the exterior that supplies temperature and humidity readings.

Freezing Records, Emily Turgeon-Brunet

Freezing Records, Emily Turgeon-Brunet

To control the humidity of the freezer, it is important to use baked mat board when rehousing your records in preparation for freezing. Baking the pieces of mat board prior to use will thoroughly dry them out. The mat board should be baked in a standard convection oven for 3 – 5 minutes at 100°C. Ensure all areas of the mat board is exposed to the heat. Once it is removed from the oven, let it cool down and then use right away so that it does not begin to absorb moisture. It is recommended to sand the corners of the pieces of mat board so they do not puncture the bags.

For full instructions on freezing records, please see our guide, found in Preparing for Digitization, Temporary Housing:


McCormick-Goodhart, M. (2003, July 31). On the Cold Storage of Photographic Materials in a Conventional Freezer Using the Critical Moisture Indicator (CMI) Packaging Method. Retrieved July 21. 2015.

Bigelow, S. (2004, March). Cold Storage of Photographs at the City of Vancouver Archives. Retrieved July 21. 2015.

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Cellulose Nitrate Negatives

Throughout our travels we have come across a few archives that were unaware they had cellulose nitrate in their collection or that film based photographic material can be made of cellulose nitrate. Cellulose nitrate is flammable and releases hazardous nitrogen oxide gases as it deteriorates. It is extremely important to identify any cellulose nitrate in your holdings as this material is unstable and requires special storage and environmental considerations.


There are many ways to identify nitrate; however, few of the methods are absolute. It is beneficial to utilize a combination of methods to identify if a negative is nitrate:

  1. Edge printing: Many, but not all, manufacturers identified the type of film along one border of the film with nitrate or safety. Safety indicates the negative is acetate. It is important to note that some early nitrate does not have edge printing.
  2. Notch codes: A notch code is a group of indentations or recesses on the edge of a piece of film to help identify the film type and brand. If there is a ‘V’ notch code first from the edge of the negative, it is nitrate, and if there is a ‘U’ notch code first from the edge of the negatives, it is acetate. Notch codes are not always accurate as the photographer may have cut the film sheet for various reasons and removed the notch code closest to the edge.
    An example of edge printing and notch codes for a nitrate negative. Photo credit: Amanda Oliver

    An example of edge printing and notch codes for a nitrate negative. Photo credit: Amanda Oliver

    An example of edge printing and notch codes for an acetate negative. Photo credit: Amanda Oliver

    An example of edge printing and notch codes for an acetate negative. Photo credit: Amanda Oliver

  3. Dates of negatives: Kodak started selling cellulose nitrate negatives in 1889 and the last year of nitrate manufacture was 1950. These dates are only applicable for Kodak and there are no other dates for other manufacturers. Also, photographers may have purchased film and used it much later than the purchase date. The dates of the negatives are not always the most reliable method for identifying negatives.
  4. Level of deterioration: There are six levels of deterioration for nitrate negatives. The negatives start to yellow and mirror, then become sticky, then the image begins to fade before turning into a brownish powder. Please visit the NEDCC for images of all the different levels of deterioration:,-care,-and-duplication

    Example of nitrate deterioration level 2. Image is yellowing and beginning to mirror.  Photo credit: Amanda Oliver

    Example of nitrate deterioration level 2. Image is yellowing and beginning to mirror. Photo credit: Amanda Oliver

  5. Testing: There are a variety of tests available to identify nitrate; however, many of these tests are damaging to the negative. The diphenylamine, burn and float test can damage the record and should all be conducted by a professional. A non-destructive test is viewing the negative through a polarizer. Polyester negatives show red and green interference colours through a polarizer whereas nitrate and acetate do not. Please visit the NPS for more information about creating a polarizer:


If available, use duplicate access copies of the negatives. Allow material stored at cool temperatures to acclimatize before handling. Wear cotton or nitrile gloves when handling nitrate negatives. This prevents oil from transferring to the negatives and acts as a heat buffer. Negatives at a higher level of deterioration ignite at lower temperatures and body heat may trigger a reaction. Try to handle negatives by their edges and avoid touching the emulsion layer. Do not expose the negatives to any heat sources. If projecting or digitizing negatives, consider using a lower watt lightbulb in the projector or scanner.

Storage and Environment

It is important to isolate nitrate from other material is the collection. These negatives off-gas nitric oxide and nitrogen dioxide, which is harmful to humans and other items in the collection. For example, gases can cause skin and eye irritations as well as respiratory issues and cause paper to become discoloured and brittle and metal to corrode. Keep the storage space well ventilated.

Nitrate negatives should be housed in PAT approved negatives sleeves or envelopes and placed in an acid-free box. If freezing the negatives, the box should be sealed in a polypropylene bag. Freezing the negatives in a sealed bag counteracts the advice to keep the storage well ventilated; however, freezing is more beneficial to negatives in good condition than well ventilated storage.

Temperature and relative humidity levels are significant factors in slowing the deterioration of nitrate negatives. Cool to cold temperatures and 30-50% RH are recommended. If possible, store negatives in a cool – cold storage vault or freezer. Freezers must be frost-free and have the ability to monitor temperature and RH. Some freezer brands are also explosive-proof, which may be beneficial for these flammable records.


Consider digitizing the nitrate negatives prior to freezing them. Digitization prior to the start of or further deterioration ensures that an accurate representation of the record is being kept. It decreases use of the original, which prevents damage caused by handling. It also ensures the original is kept in a stable environment to prevent further degradation.

Disaster Preparedness

Due to the flammable nature of this material, it is important to include cellulose nitrate in your disaster plan. Train your staff on potential scenarios involving cellulose nitrate and advise your staff on its location within your collection. Set up a monitoring schedule to check for any signs of deterioration. Ensure that there are no heat sources, such as light bulbs or radiators, near this material. It is recommended to advise your local fire department where this material is located within your facility. This is extremely important as ignited cellulose nitrate creates its own oxygen and cannot be put out using water.

Disasters may also speed up the deterioration of nitrate negatives. While we have been helping archives across Alberta recover from the June 2013 floods, we have seen nitrate negatives’ deterioration accelerated due to their time in water. It is important to identify vulnerable media in your collection and plan for evacuations, if possible.


If you decide to dispose of the cellulose nitrate in your collection, be advised that it is considered a hazardous material. Check with Alberta Environmental Protection ( or with your local environmental agency for more information on safe disposal methods for nitrate film.


The Association of Moving Image Archivists. “Identifying and Handling Nitrate Film.” The Association of Moving Image Archivists December 2008. Accessed on April 2, 2015.

Fischer, Monique. “5.1 A Short Guide to Film Base Photographic Materials: Identification, Care and Duplication.” Northeast Document Conservation Centre. Accessed on April 2, 2015.,-care,-and-duplication

Kodak. “Storage and Handling of Processed Nitrate Film.” Kodak. Accessed on April 2, 2015.

Messier, Paul. “Preserving Your Collection of Film-Based Photographic Negatives.” Rocky Mountain Conservation Centre. Access on April 2, 2015.

National Park Service. “Cold Storage: A Long-Term Preservation Strategy for Film-Based Photographic Materials.” National Park Service. Accessed on April 2, 2015.

Reilly, James M. “IPI Storage Guide for Acetate Film.” Image Permanence Institute. Last modified 1996. Accessed on April 2, 2015.

Williams, R. Scott. “Display and Storage of Museum Objects Containing Cellulose Nitrate – CCI Notes 15/3.” Canadian Conservation Institute. Accessed April 2, 2015.

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