"Homicidal" Gas Chamber Building Materials - An Analysis
Posted: Sat Aug 30, 2025 6:05 pm
Using this space as a primer, repository and analysis of the building materials and their properties, used in the "homicidal gas chambers" along with the delousing chambers.
Properties
Permeability
Permeability is a measure of how easily a material allows fluids (gases or liquids, for our purposes and from here on out, specifically gases) to pass through it under a pressure gradient. Gases can more easily pass through a material with high permeability than one with low permeability. Expressed another way, the permeability of a material determines its ability to transport gas and moisture. It is related to porosity as we will examine below.
The SI unit for permeability is m^2
Porosity
Porosity is the volume fraction of void spaces (empty space, or pores) in a material, usually expressed as a percentage or decimal. It determines how much gas can be held in the structure. Determines material capacity to absorb or store gases.
There is a direct relationship between the porosity and effective diffusion (examined below), meaning that higher porosity could result in a higher effective diffusion coefficient.
Porosity is the property that determines the material's capacity to store or "hold" gases. Larger, interconnected pores usually translate to higher permeability and faster diffusion.
Diffusion
Diffusion is the process whereby atoms or molecules spontaneously move from an area of higher concentration to lower concentration. It governs how gas moves through a material.
We can say this process is spontaneous and stochastic, in that it is seemingly inherently random. Diffusion is driven by kinetic energy, and described by Fick’s laws (see also Brownian Motion) and is heavily influenced by kinetic factors such as the pore structure of the material and the size of the atom / moluecule under consideration.
All of these properties together can be said to assist towards the absorption on a gas into a wall.
Materials
Lime Plaster
Permeability
High permeability for water vapor and gas, especially in traditional lime plaster - which is a key reason for its use in plastering, that is, Lime plaster is permeable and allows for the effective diffusion and evaporation of moisture.
Porosity
Porous structure, typically 20 - 40% open porosity depending on mix. Pores are well connected, aiding and assisting vapor movement throughout the material.
Diffusion
High diffusion rates for gases such as water vapor. This is intentional for construction purposes, in supporting the drying of walls and evaporation.
For gases like HCN (smaller, more volatile at the molecular level than water), diffusion would be somewhat faster, but of similar magnitude due to molecular size/speed (see above re Brownian motion / Fick's law)
Concrete
Permeability
Variable, but generally low permeability to gases and liquids, especially as concrete ages and hydrates.
Porosity
Lower porosity (10 - 20%) than lime plaster or brick; pores often not fully interconnected.
Pore size (nanoscale to micron-scale), with "capillary pores" dominating transport.
Diffusion
Low diffusion coefficients for both water vapor and gases, typically in the order of magnitude of 10^-12 to 10^-10.
Generally speaking - higher for more porous, less cured mixes; lower as hydration/curing advances.
Brick
Permeability
Moderate water vapor and gas permeability.
Lower permeability than lime plaster, but higher than dense, well-cured concrete.
Porosity
Porosity typically 10 - 42% (varies with brick type/manufacturer).
Most pores are open and interconnected, aiding capillary and diffusion transport.
Diffusion
Effective diffusion coefficient correlates directly with porosity; literature values for water vapor typically 10^-10 to 10^-9 m^2/s
Iron Content
Lime & Cement Plaster
The iron content of mortars results primarily from the added sand (up to 4%. Where this has been measured by Rudolf, the readings present as 10,000 and 11,000 PPM respectively in the walls of the Homicidal Gas Chamber and in the Delousing Chambers this ranges from 6,000 to 19,000 PPM. Note, sample 11 from the Delousing Chamber as per Rudolf despite having a relatively low iron content reading of 6,000 PPM, still demonstrates HCN reading of 2,600 PPM, signaling a 36% conversion of available iron oxides. This indicates that relatively low iron content is not the limiting factor.
Concrete
The iron content of regular Portland cement is usually between 1-5%. Sand added to concrete and cement can also have high iron content (up to 4%). In the samples measured by Rudolf, the iron contents ranged from 13,000 - 20,000 PPM in the Homicidal gas chamber.
Brick
Iron oxide content ranges on average from 2-4%. However due to the sintering processes involved in manufacturing, it is commonly understood that the reactivity of the iron oxides is reduced, mostly due to reduced surface area, and so this will impede any Prussian Blue formation in the interior of the material. The immediate surface of the brick however is an exception to this rule due to the kinetics involved during natural erosion and wear and tear, will increase the surface area and allow for iron at the surface to react. This is what we see at the Delousing Chambers.
Alkalinity
Freshly poured concrete and cement mortar will be in the range of 12-13 , and will slowly reduce down to around 8.5 over the period of months to years, due to a process called carbonation.
In contrast, Lime mortars (of the kind used in the Delousing chamber) hold their alkalinity relatively shorter than cement mortars, and therefore this means that the materials in the Homicidal gas chambers would be even more hospitable to the formation of Prussian Blue than that of the Delousing chambers.
=
From this analysis we can begin to model the interior of the room(s), as constructed by bricks and lime / cement mortar with a lime / cement plaster on the walls, and a concrete ceiling.
We can deal firstly with the concrete ceiling. The concrete ceiling has the lowest assumed rate of absorption of gaseous material. However, it also has by far and away the highest surface area (as measured in m^2 per gram).
A large surface area, as found in cement mortars and concrete, is especially favourable to the solid-liquid interface reaction between the solid iron ions and the cyanide in solution (capillary moisture with dissolved cyanide). These materials moreover have the advantage of retaining an alkaline medium for longer periods of time, so that the cyanide accumulated in the masonry is not lost and has enough time to react with iron.
As mentioned, a large surface area of the solid-liquid interface (iron oxide–cyanide solution) is very large, and therefore favourable to the formation of Prussian Blue. This interface is potentially extraordinarily large in cement mortars and concrete due to their huge interior, microscopically rough surfaces of approximately 200 m2 per gram, see image below. This is an image of a Lime based mortar (larger image) and inset with a cement based mortar (small image) at the same level of magnification.
Put simply, having a large surface area means that more of the iron is exposed to cyanide along this interface surface, and given how accommodating this environment is, it is far more inclined to react than materials with lower relative surface area (like lime)
As we have seen, the cement plaster has been determined to have an iron content in the range of 10,000 - 11,000 ppm, which is in the same range as that of the lime plaster in the Delousing Chambers (6,000 - 19,000ppm). We have already showed that even plaster samples with the lowest iron content reading of 6,000ppm in the Delousing Chambers produced HcN readings of 2,600 ppm, and so the range in the homicidal gas chamber can be said to support its formation. The absorption properties, along with surface area properties discussed above along with the kinetics involved can all be said to support it’s formation too.
We unfortunately do not have a direct measurement of the iron content of bricks in the homicidal gas chamber, however the control sample bricks taken from the inmate barracks and delousing chambers show iron content readings within the expected range of 2.5% - 4.7%, the bricks can be said to be within the range of iron content expected.
Sources
A comparative study of the durability and behaviour of fat lime and feebly-hydraulic lime mortars - S. Pavia et al
Porosity Measurement of Low Permeable Materials Using Gas Expansion Induced Water Intrusion Porosimetry (GEIWIP) - M. Jarrahi et al
DIN 4108, Part 4
The Surface Area of Hardened Cement Paste as Measured by Various Techniques - Thomas et al
The pH of Cement-based Materials: A Review – Yousuf et al
The Chemistry of Auschwitz - Germar Rudolf
Properties
Permeability
Permeability is a measure of how easily a material allows fluids (gases or liquids, for our purposes and from here on out, specifically gases) to pass through it under a pressure gradient. Gases can more easily pass through a material with high permeability than one with low permeability. Expressed another way, the permeability of a material determines its ability to transport gas and moisture. It is related to porosity as we will examine below.
The SI unit for permeability is m^2
Porosity
Porosity is the volume fraction of void spaces (empty space, or pores) in a material, usually expressed as a percentage or decimal. It determines how much gas can be held in the structure. Determines material capacity to absorb or store gases.
There is a direct relationship between the porosity and effective diffusion (examined below), meaning that higher porosity could result in a higher effective diffusion coefficient.
Porosity is the property that determines the material's capacity to store or "hold" gases. Larger, interconnected pores usually translate to higher permeability and faster diffusion.
Diffusion
Diffusion is the process whereby atoms or molecules spontaneously move from an area of higher concentration to lower concentration. It governs how gas moves through a material.
We can say this process is spontaneous and stochastic, in that it is seemingly inherently random. Diffusion is driven by kinetic energy, and described by Fick’s laws (see also Brownian Motion) and is heavily influenced by kinetic factors such as the pore structure of the material and the size of the atom / moluecule under consideration.
All of these properties together can be said to assist towards the absorption on a gas into a wall.
Materials
Lime Plaster
Permeability
High permeability for water vapor and gas, especially in traditional lime plaster - which is a key reason for its use in plastering, that is, Lime plaster is permeable and allows for the effective diffusion and evaporation of moisture.
Porosity
Porous structure, typically 20 - 40% open porosity depending on mix. Pores are well connected, aiding and assisting vapor movement throughout the material.
Diffusion
High diffusion rates for gases such as water vapor. This is intentional for construction purposes, in supporting the drying of walls and evaporation.
For gases like HCN (smaller, more volatile at the molecular level than water), diffusion would be somewhat faster, but of similar magnitude due to molecular size/speed (see above re Brownian motion / Fick's law)
Concrete
Permeability
Variable, but generally low permeability to gases and liquids, especially as concrete ages and hydrates.
Porosity
Lower porosity (10 - 20%) than lime plaster or brick; pores often not fully interconnected.
Pore size (nanoscale to micron-scale), with "capillary pores" dominating transport.
Diffusion
Low diffusion coefficients for both water vapor and gases, typically in the order of magnitude of 10^-12 to 10^-10.
Generally speaking - higher for more porous, less cured mixes; lower as hydration/curing advances.
Brick
Permeability
Moderate water vapor and gas permeability.
Lower permeability than lime plaster, but higher than dense, well-cured concrete.
Porosity
Porosity typically 10 - 42% (varies with brick type/manufacturer).
Most pores are open and interconnected, aiding capillary and diffusion transport.
Diffusion
Effective diffusion coefficient correlates directly with porosity; literature values for water vapor typically 10^-10 to 10^-9 m^2/s
Iron Content
Lime & Cement Plaster
The iron content of mortars results primarily from the added sand (up to 4%. Where this has been measured by Rudolf, the readings present as 10,000 and 11,000 PPM respectively in the walls of the Homicidal Gas Chamber and in the Delousing Chambers this ranges from 6,000 to 19,000 PPM. Note, sample 11 from the Delousing Chamber as per Rudolf despite having a relatively low iron content reading of 6,000 PPM, still demonstrates HCN reading of 2,600 PPM, signaling a 36% conversion of available iron oxides. This indicates that relatively low iron content is not the limiting factor.
Concrete
The iron content of regular Portland cement is usually between 1-5%. Sand added to concrete and cement can also have high iron content (up to 4%). In the samples measured by Rudolf, the iron contents ranged from 13,000 - 20,000 PPM in the Homicidal gas chamber.
Brick
Iron oxide content ranges on average from 2-4%. However due to the sintering processes involved in manufacturing, it is commonly understood that the reactivity of the iron oxides is reduced, mostly due to reduced surface area, and so this will impede any Prussian Blue formation in the interior of the material. The immediate surface of the brick however is an exception to this rule due to the kinetics involved during natural erosion and wear and tear, will increase the surface area and allow for iron at the surface to react. This is what we see at the Delousing Chambers.
Alkalinity
Freshly poured concrete and cement mortar will be in the range of 12-13 , and will slowly reduce down to around 8.5 over the period of months to years, due to a process called carbonation.
In contrast, Lime mortars (of the kind used in the Delousing chamber) hold their alkalinity relatively shorter than cement mortars, and therefore this means that the materials in the Homicidal gas chambers would be even more hospitable to the formation of Prussian Blue than that of the Delousing chambers.
=
From this analysis we can begin to model the interior of the room(s), as constructed by bricks and lime / cement mortar with a lime / cement plaster on the walls, and a concrete ceiling.
We can deal firstly with the concrete ceiling. The concrete ceiling has the lowest assumed rate of absorption of gaseous material. However, it also has by far and away the highest surface area (as measured in m^2 per gram).
A large surface area, as found in cement mortars and concrete, is especially favourable to the solid-liquid interface reaction between the solid iron ions and the cyanide in solution (capillary moisture with dissolved cyanide). These materials moreover have the advantage of retaining an alkaline medium for longer periods of time, so that the cyanide accumulated in the masonry is not lost and has enough time to react with iron.
As mentioned, a large surface area of the solid-liquid interface (iron oxide–cyanide solution) is very large, and therefore favourable to the formation of Prussian Blue. This interface is potentially extraordinarily large in cement mortars and concrete due to their huge interior, microscopically rough surfaces of approximately 200 m2 per gram, see image below. This is an image of a Lime based mortar (larger image) and inset with a cement based mortar (small image) at the same level of magnification.
Put simply, having a large surface area means that more of the iron is exposed to cyanide along this interface surface, and given how accommodating this environment is, it is far more inclined to react than materials with lower relative surface area (like lime)
As we have seen, the cement plaster has been determined to have an iron content in the range of 10,000 - 11,000 ppm, which is in the same range as that of the lime plaster in the Delousing Chambers (6,000 - 19,000ppm). We have already showed that even plaster samples with the lowest iron content reading of 6,000ppm in the Delousing Chambers produced HcN readings of 2,600 ppm, and so the range in the homicidal gas chamber can be said to support its formation. The absorption properties, along with surface area properties discussed above along with the kinetics involved can all be said to support it’s formation too.
We unfortunately do not have a direct measurement of the iron content of bricks in the homicidal gas chamber, however the control sample bricks taken from the inmate barracks and delousing chambers show iron content readings within the expected range of 2.5% - 4.7%, the bricks can be said to be within the range of iron content expected.
Sources
A comparative study of the durability and behaviour of fat lime and feebly-hydraulic lime mortars - S. Pavia et al
Porosity Measurement of Low Permeable Materials Using Gas Expansion Induced Water Intrusion Porosimetry (GEIWIP) - M. Jarrahi et al
DIN 4108, Part 4
The Surface Area of Hardened Cement Paste as Measured by Various Techniques - Thomas et al
The pH of Cement-based Materials: A Review – Yousuf et al
The Chemistry of Auschwitz - Germar Rudolf