For sealing the surface of exterior brick or plaster/stucco/pargetting
before painting. Black or very dark grey material, so hard it almost
seems like a glaze fired on to the surface. Almost impossible to remove
except mechanically with colateral damage. Cannot try heat as underlying
surface is thin and unknown water content so may crack or steam burst
apart. Proprietary name or generic name for the material or process?
Some sort of stove-enamel?

On 24 Jan 2015, N_Cook grunted:

For sealing the surface of exterior brick or plaster/stucco/pargetting
before painting. Black or very dark grey material, so hard it almost
seems like a glaze fired on to the surface. Almost impossible to remove
except mechanically with colateral damage. Cannot try heat as underlying
surface is thin and unknown water content so may crack or steam burst
apart. Proprietary name or generic name for the material or process?
Some sort of stove-enamel?

The ground floor floorboards of my Edwardian house are set on brick piers,
between which the builders floated some form of bitumenous material over a
thin of rubble for damp-roofing purposes, forming a flat, black, shiny
layer. I wonder if that's a clue to your coating? Worth trying out a
petroleum-based solvent and wire brush?

--
David

On 25/01/2015 08:41, Lobster wrote:
On 24 Jan 2015, N_Cook grunted:

For sealing the surface of exterior brick or plaster/stucco/pargetting
before painting. Black or very dark grey material, so hard it almost
seems like a glaze fired on to the surface. Almost impossible to remove
except mechanically with colateral damage. Cannot try heat as underlying
surface is thin and unknown water content so may crack or steam burst
apart. Proprietary name or generic name for the material or process?
Some sort of stove-enamel?

The ground floor floorboards of my Edwardian house are set on brick piers,
between which the builders floated some form of bitumenous material over a
thin of rubble for damp-roofing purposes, forming a flat, black, shiny
layer. I wonder if that's a clue to your coating? Worth trying out a
petroleum-based solvent and wire brush?


+1
Raw bitumen is very shiny and brittle.

On 25/01/2015 10:43, stuart noble wrote:
On 25/01/2015 08:41, Lobster wrote:
On 24 Jan 2015, N_Cook grunted:

For sealing the surface of exterior brick or plaster/stucco/pargetting
before painting. Black or very dark grey material, so hard it almost
seems like a glaze fired on to the surface. Almost impossible to remove
except mechanically with colateral damage. Cannot try heat as underlying
surface is thin and unknown water content so may crack or steam burst
apart. Proprietary name or generic name for the material or process?
Some sort of stove-enamel?

The ground floor floorboards of my Edwardian house are set on brick
piers,
between which the builders floated some form of bitumenous material
over a
thin of rubble for damp-roofing purposes, forming a flat, black, shiny
layer. I wonder if that's a clue to your coating? Worth trying out a
petroleum-based solvent and wire brush?


+1
Raw bitumen is very shiny and brittle.

Perhaps over time it seeps in and incorporates itself with the base
material. I'll try petrol next time I come across it, methyl chloride
and the recent non methyl stuff did not soften it. Heavy wire brushing
it, removed it on a test section, but also removed the top plaster with
it. As its survived this long well keyed in , left it be, rather than
going back to the underlying surface.
No tarry smell noticed in the abbrassion process, but the glassy
appearance is consistent with block tar

On Sunday, January 25, 2015 at 12:08:05 PM UTC, N_Cook wrote:
On 25/01/2015 10:43, stuart noble wrote:
On 25/01/2015 08:41, Lobster wrote:
On 24 Jan 2015, N_Cook grunted:

For sealing the surface of exterior brick or plaster/stucco/pargetting
before painting. Black or very dark grey material, so hard it almost
seems like a glaze fired on to the surface. Almost impossible to remove
except mechanically with colateral damage. Cannot try heat as underlying
surface is thin and unknown water content so may crack or steam burst
apart. Proprietary name or generic name for the material or process?
Some sort of stove-enamel?

The ground floor floorboards of my Edwardian house are set on brick
piers,
between which the builders floated some form of bitumenous material
over a
thin of rubble for damp-roofing purposes, forming a flat, black, shiny
layer. I wonder if that's a clue to your coating? Worth trying out a
petroleum-based solvent and wire brush?


+1
Raw bitumen is very shiny and brittle.

Perhaps over time it seeps in and incorporates itself with the base
material. I'll try petrol next time I come across it, methyl chloride
and the recent non methyl stuff did not soften it. Heavy wire brushing
it, removed it on a test section, but also removed the top plaster with
it. As its survived this long well keyed in , left it be, rather than
going back to the underlying surface.
No tarry smell noticed in the abbrassion process, but the glassy
appearance is consistent with block tar

Paraffin is a good solvent for bitumen. But if it is that it tends to soak into the surface - and you cant paint onto it, except with more bitumen.


NT

On 25/01/2015 12:58, wrote:
On Sunday, January 25, 2015 at 12:08:05 PM UTC, N_Cook wrote:
On 25/01/2015 10:43, stuart noble wrote:
On 25/01/2015 08:41, Lobster wrote:
On 24 Jan 2015, N_Cook grunted:

For sealing the surface of exterior brick or plaster/stucco/pargetting
before painting. Black or very dark grey material, so hard it almost
seems like a glaze fired on to the surface. Almost impossible to remove
except mechanically with colateral damage. Cannot try heat as underlying
surface is thin and unknown water content so may crack or steam burst
apart. Proprietary name or generic name for the material or process?
Some sort of stove-enamel?

The ground floor floorboards of my Edwardian house are set on brick
piers,
between which the builders floated some form of bitumenous material
over a
thin of rubble for damp-roofing purposes, forming a flat, black, shiny
layer. I wonder if that's a clue to your coating? Worth trying out a
petroleum-based solvent and wire brush?


+1
Raw bitumen is very shiny and brittle.

Perhaps over time it seeps in and incorporates itself with the base
material. I'll try petrol next time I come across it, methyl chloride
and the recent non methyl stuff did not soften it. Heavy wire brushing
it, removed it on a test section, but also removed the top plaster with
it. As its survived this long well keyed in , left it be, rather than
going back to the underlying surface.
No tarry smell noticed in the abbrassion process, but the glassy
appearance is consistent with block tar

Paraffin is a good solvent for bitumen. But if it is that it tends to soak into the surface - and you cant paint onto it, except with more bitumen.


NT


Yes, no difficulty lifting the old paint off this old surface but could
not go any deeper.

On 24/01/2015 10:55, N_Cook wrote:
For sealing the surface of exterior brick or plaster/stucco/pargetting
before painting. Black or very dark grey material, so hard it almost
seems like a glaze fired on to the surface. Almost impossible to remove
except mechanically with colateral damage. Cannot try heat as underlying
surface is thin and unknown water content so may crack or steam burst
apart. Proprietary name or generic name for the material or process?
Some sort of stove-enamel?

My guess would be "paint" rather than bitumen.

Strictly, "stove enamelling" is a coating which is cured by heating in
an oven. The expression may be used for organic coatings where
temperatures of ~ 150 C are used to drive off solvents and/or polymerise
the resins, or for true enamelling where a glass-based product is fused
on to a metal surface at maybe 700 C (like glazing pottery).

On 25/01/2015 16:56, newshound wrote:
On 24/01/2015 10:55, N_Cook wrote:
For sealing the surface of exterior brick or plaster/stucco/pargetting
before painting. Black or very dark grey material, so hard it almost
seems like a glaze fired on to the surface. Almost impossible to remove
except mechanically with colateral damage. Cannot try heat as underlying
surface is thin and unknown water content so may crack or steam burst
apart. Proprietary name or generic name for the material or process?
Some sort of stove-enamel?

My guess would be "paint" rather than bitumen.

Strictly, "stove enamelling" is a coating which is cured by heating in
an oven. The expression may be used for organic coatings where
temperatures of ~ 150 C are used to drive off solvents and/or polymerise
the resins, or for true enamelling where a glass-based product is fused
on to a metal surface at maybe 700 C (like glazing pottery).

If you blow-lamp torched a stove-enamel preparation over a surface and
thickness that could take that amount of heat transfer for a relatively
short time, give something like a virified surface, well bonded into a
porous base structure