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Fire retardents used

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Fire retardants

Borate salts were used in the past to fight wildfires but were found to sterilize the soil, were toxic to animals, and are now prohibited. Newer retardants use ammonium sulfate or ammonium polyphosphate with attapulgite clay thickener or diammonium phosphate with a guar gum derivative thickener. These are not only less toxic but act as fertilizers to help the regrowth of plants after the fire. Fire retardants often contain wetting agents, preservatives and rust inhibitors and are colored red with ferric oxide or fugitive color to mark where they have been dropped. Brand names of fire retardants for aerial application include Fire-Trol and Phos-Chek.

Some water-dropping aircraft carry tanks of a guar gum derivative to thicken the water and reduce runoff.


Forest Service Fire and Aviation Management (F&AM) on matters relating to fire chemical products by:



(Submitted by P. OEGEMA, ITRATECH)





There are three classes of forest fire chemicals:


         The “short term” retardants (polymers), which have been used predominantly in the 70’s or the “water enhancers” (gels, absorbents,..), which are offered now, are primarily  thickeners, supposed to improve the rheology of the drops,

         The “foaming agents”, (class A foams) which have been refashioned in the 80’s, when the cosmetic chemical bases became less expensive. Their basic action is that they improve the cooling effects of water. They produce better coating and wrap up of the fuels and retain moisture for a while. However, when the water has evaporated, they do not have effect anymore.

         The “long term” retardants (retardants), whose operational efficacy is provided by an active salt, usually an ammonium phosphate, which alters the pyrolysis process (2). Water is necessary for their transportation, but when the water evaporates, the efficiency of the product is retained, till the time it is washed off by the rain or successive dew. Long term retardants have been in use for over thirty years now.


Combination of some of the above cited products is still possible.


For example, thickeners have been added to retardants for many years. Expected result was primarily the enhancement of the drops (less evaporation and less drift), especially when the drop height is above 200 feet. Conversely, thickeners tend to cling to the canopy and do not reach the understory.


About five years ago, the Canadian Fire Agencies (with the exception of SASKATCHEWAN), decided to mix retardant and foam (2).

Advantages of such a mix are reported by Wally Mc-Cullogh (3): “I have seen many drops, straight retardant drops and retardant plus foam. Even if the foam introduces some turbulences, and this is not proven, with foam you get better coverage and wrap up. It also allows the retardant to spread”.


Forest fire fighting chemicals need to be conveyed through more or less complicated logistics, depending on their features and the applications in which they are used (aerial or ground applications).


Foam is currently used with water bombers and from the ground. Retardant is mainly used from air-tankers and “heli-tankers”. However, retardant  has been experimented from the ground with excellent results especially with the C.O.G.E.F.F.O. in Le Gard Department (France), and in Le Var Department (France) (4).


Aerial applications were born in the 30’s (5), and in the USA. There has been a large expansion in the use of air-tankers, and heli-tankers as well.


It is out of the scope of this paper to review all the available aerial resources. To be short, let us say that several categories of tankers are available, from less than 800 gallons to more than 3,000 gallons, and maybe in the future, 12,000 gallons to 24,000 gallons (6) for the air-tankers.

Delivery systems make the difference. They can be conventional delivery systems, or pressurized systems (MAFFS 1 and MAFF 2), or constant flow delivery systems (AUC, MARSH, …) (7).

Anyway, the retardant manufacturers have to get and maintain a good grasp of the features of the aerial delivery systems and more generally the logistics, in order to adapt their products to the aircraft and helicopters, or ground logistics, which are or could be currently used.


The retardant manufacturers are required to either just supply with the product (Tunisia, Israel, Turkey,…), or have also to maintain the retardant base equipment (France), or to offer a “mixing and loading” package (USA, Canada, Spain,…).


The following only deals with the retardant business.





The annual average turn over of forest fire fighting chemicals is assessed to be around 42ME (53 M$), which is the billing of a medium sized business.


The retardant market, worldwide is shared between two US companies:

i)                    ASTARIS, (St LOUIS, M0), a subsidiary of both SOLUTIA and FMC, whose trade products are the PHOS-CHECK brand, especially the D-75 grade dry powder,

ii)                   FIRE-TROL HOLDINGS, L.L.C., (Phoenix, AZ), whose trade products are the FIRE-TROL brand, especially, the FIRE-TROL LC’s (Liquid Concentrates).


The formulations offered by ASTARIS are the same everywhere, while they could be different for FIRE-TROL HOLDINGS, L.L.C..

As an example, the aerial formulation of the FIRE-TROL liquid concentrate is FIRE-TROL LCA-R in the US, and  FIRE-TROL 931 in Canada and Europe.

For these two firms, the main market is made by the US Fire Agencies (US Forest Service, Bureau of Land Management, California Department of Forests, …).

If the US market is 100, then the Canadian market is 30, and the European market (including Mediterranean countries), is 10.

The retardant manufacturers have formed branches or appointed licensees and distributors outside the US.


The growth of the retardant market is not strong, although there is big potential in Eastern Europe. Only peaks are recorded (in the US in 2000 and 2002, or in Canada in 2003, or in France and Spain in 2003 also), linked to the weather conditions. In some countries (Italy, Greece,…), the CANADAIR CL-415 achieved a breakthrough which resulted in minimizing the use of retardants.


Consequently, the strategies of the retardant manufacturers are very limited. The retardant Strategic Business Area (SBA) can only be put in two quadrants of the analytical matrix of  the Boston Consulting Group (8): either the “dead weight” quadrant, or the “cash cow” quadrant, depending on the competitive position of the firm.

If the competitive position of the firm is strong, then the SBA will be located in the cash cow quadrant, and the strategic orientation will come to make profitable the operation and hold the acquired position. This has been the FIRE-TROL situation in the last years. Fire-Trol had 50% of the US market in the 1990’s and 70% in 2001.

Conversely, ASTARIS and predecessors were losing market shares at the same time and the retardant SBA could be found in the dead weight quadrant where you only can give up and desinvest.


ASTARIS reacted with a strategy of differenciation (better to say “antidifferenciation” in this case). They tried, in a first stage, to offer powder fluid retardants (9), aiming at  “ providing products exhibiting both the handling ease of water-like and the performance of gum thickened retardants, providing fire management agencies with a full range of viscosity alternatives”.


ASTARIS got some experimental bases in the US and in Canada. Reported results are controversial.


Besides, they have lately offered two liquid concentrate formulations : the PHOS-CHECK LC 95A and the PHOS-CHECK LC 95D, two products formulated with an Ammonium Poly Phosphate (APP), which have been fully approved by the MTDC Missoula Lab, controlled by the US Forest Service. As these products have not been tested in the field yet, it is difficult to give any information about them.

However, it appears that the R/D effort of ASTARIS has come to duplicate the FIRE-TROL formulas, but with some expected improvements: the corrosion inhibitor is different, and viscosity building is made when the concentrate is blended with water.


Meanwhile, FIRE-TROL was attempting to make approved a new retardant formulated with an Ammonium Thiosulfate (ATS).


So, it looks like that the two competitors have been or are now focusing they R/D efforts on liquid concentrates, considering the viewpoint of the end users (10).


The strategies of the two competitors would have been relevant if they had continued on this coarse.

In contradiction to all classics regarding the strategies, ASTARIS started (2001)  to reduce its prices across-the-board, in an attempt to recapture market share lost in the 1998-2000 contracts, which triggered a “pricing war”. This low balling method has weakened the two competitors.


The strategy that ASTARIS seems to have chosen, attempting to denigrate the competitor’s product, what we called a strategy of “antidifferenciation”, has not been a good thing for the businesses in the profession. This approach appears to have been enhanced by the actions taken by the US Forest Service.


In fact, in 2000, FIRE-TROL products were suspended from use, following a study of the USGS (US GEOLOGICAL SURVEY) that brought fears regarding supposed additional toxicity on water streams of the corrosion inhibitor used in the formulation of these products ( sodium ferrocyanide).

FIRE-TROL protested this decision and the ban lasted only three weeks, but the debate continued.


Finally, FIRE-TROL HOLDINGS, L.L.C., , has filed a lawsuit against the USDA-Forest Service over a number of issues. The lawsuit questions the scientific basis for the ban on retardant containing Sodium Hexacyanoferrate II (YPSoda), the requirement for gum thickened retardants and the USDA Forest Service, specifically the MTDC Missoula Lab, failure to follow its own procedures, when making changes to the Qualified Products List (QPL).


The debate became public at the end of 2003 (12). On February 17, 2004, the Canadian Interagency Forest Fire Centre (CIFFC),  whose mandate is “to provide operational forest fire management services to Member Agencies that will, by agreement, gather, analyze and disseminate fire management information to ensure a cost effective sharing of resources; and actively promote, develop, refine, standardize and provide services to Member Agencies that will improve forest fire management in Canada” stated that “CIFFC has emphatically and consistently represented the collective Canadian User Agencies’ position that Canada will not be adopting the proposed US policies of prohibiting the use of retardant products containing Sodium Hexacyanoferrate II or requiring gum thickened products” (11).


The ambiance is not favorable to technical researches, a situation which could have been predicted as soon as 1998.

In that way, the commitment of the EC to go forward on the retardant issues, dedicating some European Research Programs to that topic, has been very welcome.


Precisely, in Europe, the leader for retardants is a small business (BIOGEMA S.A.) located in the South-East part of France.

BIOGEMA is the FIRE-TROL licensee in Europe and Mediterranean countries.




The demand considering the retardants is directly the expression of political motives, thus available budgets, and depends upon the availability of “retardant carriers”. The assertion “the Environmental issues are the monopoly of rich countries”, makes the situation even more ambiguous.

Things are complex and simple at the same time. Sorting all types of considerations, there are some axis that could be emerging.

In the first place, a steady truth is that “when you miss the initial attack, you will lose the battle” (13).

It is statistically demonstrated that poor initial attack generates dramatic situations, (California, 2003, Portugal, 2003,…).

Initial attack is the key, and in all cases, big fires are those for which the initial attack has failed.

In Europe, as far as we know, only France and Spain are practicing the “one strike concept” (5), at least partly.


The second idea is the apparent paradox that “more retardant at the entry means less retardant at the exit”.

A fundamental principle which emerged in Europe is to obtain a determinant effect of the retardant on starting fires. The expectation of the end users is to slow down the fire till the contact is established by the ground resources (France, Spain,..), or more: stop the fire since no ground resources are available (IsraŽl, Tunisia, …).

This can only be obtained with high range retardants, with dilutions (“mix ratios”) that contain a high percentage of active salt.


The reactivity is another requirement of the customers. The retardant must be delivered when needed, which imposes that the retardant mixing plants are not too far from the retardant bases on one hand and, on the other hand,  that the concentrate storage facilities on the retardant bases have been properly tailored.


In remote countries like Turkey, a lot of care must be paid to the storing organization in order not to be short of inventory.

Finally, the trend is visible that, at least in Europe, the clients want to buy a system and not only a product. This mentality is translated into a total package requirement or a demand of efficiency (do the things right) instead of efficacy (do the right things).

This can be seen in Spain, where the retardant supply has to be provided by an air-operator who is responsible for the implementation of the air-tankers, but also has to set up the retardant bases and operate them.


This transfer of responsibility (privatization or externalization) may lead the retardant manufacturers to take initiatives related to technology or industrial research.




As far as we know, two European Research Programs have dealt with the forest fire fighting chemicals and, in particular with the retardants: the A.C.R.E Project, and the E.R.A.S Project ,the later still ongoing.

For the retardant industry, the works and findings reported in these two projects have a considerable interest.

The ERAS Program has been a way to “re-zero” the state of knowledge about the retardants in freeing oneself from the US control in terms of R/D. That doesn’t mean that the researches made in the US are not helpful. But they were made according to the cultural schemes that this country has got.

It was timely that specific European researches are made in the attempt to focus on the particular situation of European and Mediterranean countries with respect to the advantages or disadvantages in using forest fire fighting chemicals.

In Europe and Mediterranean area, the land, the winds, the fuel structures, the resources, the organizations,…., are different of what can be found in the US or in Canada. The researchers involved in the European projects have been wise enough not to reinvent the wheel, and to try to recognize the requirements of the Mediterranean forest fire fighters.

The will of European leaders to organize a cooperation between the fundamental research, the industrial research, the manufacturers and the field people has also been a great plus.

Let us give some examples of the fruitful results of this cooperation.

Using microscopic techniques, the NTUA (14) has concluded that “Finally, the commercial product seems to have a greater impact on the needles pyrolysis, compared to that of a pure chemical. This may be due to the improved physicochemical characteristics of the commercial product, due to the presence of specific additives resulting in a better adhesion on the needles surface, than in the case of the pure chemical”.

The manufacturer in charge of the “commercial product” tested has identified the reasons of that phenomenon, and has optimized the control of one of the ingredients of the formula.


The University of AVEIRO (PORTUGAL) has studied the modeling of the Atmospheric dispersion of a retardant cloud (15). Their results have been used by the French Security Civile for figuring out the size and final velocity of the retardant droplets in case of an emergency dump (16), and function of the drop height.


The CEREN provided with extensive studies regarding gum thickened products that will help the manufacturers in their efforts the quantity of polymers that they could include in their formulas (17).


We could multiply the illustrations. Anyway, there is no doubt that the European programs findings have been already interpreted in terms of improved practices.






It is premature to be conclusive about the ongoing ERAS Program. Expected results will be of paramount importance regarding the interest of using retardant as part of the forest fire fighting tool.

First results have again demonstrated the large advantage of using retardants from the ground (4). In the near future, economic issues regarding this purpose should be considered.

Thickened retardants look like they are not very useful in European and Mediterranean countries. The researchers have shown that, technically speaking, a viscosity of the retardant dilute around 400 cps in the diluted retardant, would be an optimum. However, the Value Analysis shows that the cost effectiveness is still in favor of a unthickened product, as long as the drop heights are not exceeding 200’ AGL. As a matter of fact, gum is difficult to handle, expensive and susceptible to bacteria deterioration. The French Security Civile decided not to go into that track (18).

The ERAS 3-D tests will bring additional information. As they have not been run yet, it is difficult to say anything about it.

Regardless of the conclusions that ERAS partners will issue at the end of this project, our suggestions for future European research contribution are as follows:


-Implement a set of European forest fire chemical specifications, including the protocols of the tests to be run and standardizing the equipment or devices involved.

Different countries in Europe could work on that project. The bottom line is to design a method that could approve forest fire chemicals according to the same requirements in all European and Mediterranean countries, and assign a European Lab to do the job.


-Work on the toxicity of the forest fire chemicals in regard to the real and specific risks or hazards than can be expected in the Mediterranean area. It is not a problem  to deal with what could happen if a retardant drop hits a water stream, since it is quite exceptional in our areas (“never happened”, says Bruno GUILLOT), (19). It is worthwhile to review the kind of risks or hazards that forest fire chemical application could trigger. Especially on orchards, olive trees, ….

Some studies have been made in the past, especially on the vineyards (20), and more lately on seeds (21), but no overall study has been conducted so far. A environmental  “risk assessment” study, however, would be welcome.


-Improve the performance of the forest fire fighting chemicals, by working on stabilizers, especially in the attempt to avoid the running off of the ground retardants when used on a pre-suppression basis. It is not realistic that the fundamental research deals with active salts concerns. As a matter of fact, the technical or scientific aspects with respect to the retardant salts imply studies regarding the supply safety, the economic terms, the handling …., which are typically the problems of the Industry.


-Optimize the number and the size (payload) of air-tankers and the mix of helicopters, water bombers and fixed wing air-tankers, in each of the European countries, a large study to be connected to a “federal” European view.