Agriculture Reference
In-Depth Information
●
The washed Suffolk rubber, although dense in texture, cut reasonably well
with few inclusions or air pocket voids, but finished well with abrading and
good arrisses.
●
The unwashed Suffolk rubber was noticeably harder to cut, especially towards
the middle, with large inclusions, yet again it finished well with good arrisses.
●
The Hampshire rubber cut the easiest of all the modern rubbers, but due
to a much coarser sand content had fragile arrisses that needed care. The
integral breeze was evident in a flash burn towards the harder exposed core
of the brick.
●
The unwashed Buckinghamshire rubbing brick (trial brick 1) rubbed
and cut well with satisfactory arrisses, and the inclusions presented little
resistance. The fully washed rubbing brick (trial brick 2) had only minor
inclusions and though firmer it rubbed and cut well with good arrisses.
The opinions of those that took part in these tests was that, generally, most
of the modern rubbing bricks tend to compare with the washed rubbers from
the mid-nineteenth century onwards and some of the earlier, better quality,
naturally clean-bodied bricks, in respect of texture and appearance. The
Hampshire and Buckinghamshire unwashed rubbers have a texture and colour
that particularly complements some sixteenth through to the eighteenth-cen-
tury gauged work. Both were quite soft to cut and rub, although the integral
fuel of the former can sometimes cause the brick to burn harder than accept-
able for a consistent rubbing brick quality. The overall hardness of the others
would seem to confirm that modern rubbers are burned to a higher tempera-
ture than their historical counterparts and therefore do not cut and rub quite
so readily. Clearly, in terms of cutting, the majority of these modern bricks are
slightly suited more towards machine cutting than hand cutting, although all
can be cut by hand tools.
Case Study: The Characteristics and Properties of
Rubbing Bricks
By Dr Belinda Colston CSci CChem FRSC, Senior Lecturer,
Lincoln University, England
Being easily cut and rubbed, and carved, it is easy to think that rubbing
bricks are unable to withstand the weather and thus unsuited for construc-
tional work. This ignores the survival of well-detailed and constructed work
on many historic buildings. It is a fact that, after these bricks have been laid,
their surfaces become hard (similar to freshly worked limestone) over time,
so enabling rubbers to withstand even the polluted atmospheres of big towns
and cities.
