In a message dated 11/23/98 4:52:32 PM Eastern Standard Time,
[log in to unmask] writes:
> Prepackaged lime cement mortars to meet Type K, O, N, S or M are available
> under our "SPEC-JOINT 46" label. It's not that these mixes are rocket
> science, but a controlled blend of consistent ingredients does represent a
> convenience for those who won't bother (or can't br trusted) to mix their
> own.
The controversy here is a perception that the lime in these pre-packaged mixes
is crushed limestone and not hydrated lime.
We have ordered in the past custom mixes with hydrated lime and colors, the
mixes being approved via site mock-ups on the wall before ordering. The mixes
had to be ordered by the pallet. We had a lot of mix left over. It did take
out the variable of a mechanic on site trying each day to replicate the colors
of the previous days and the extra cost of the mixes was offset by a savings
in labor as well as less headache for the entire project team.
One problem with mixing colors on site is that you cannot see the colors
during the process and there is an intuitive temptation to spike the mix just
a little bit each time. Some colors show up sooner in the process. Solomon
Grind-Chem colors, which I prefer, you can mix dry and see nothing, then add
water and it seems way too dark, and it is not until 14 days later, or more,
that you really get to see if the finished color will match. If it does not
match then it gets to be a headache to explain why. It could be improper
proportioning, it could be a slightly off-tinted Portland, it could be
improper curing, or that the humidity was different on that day. If you have a
large repoionting project this can be a problem in project management to
backtrack. Mechanics are not always very good at remembering the original mix,
or passing it on to their fellow crew members. We try to keep one mechanic on
the mix consistent through the entire project, but this does not work if they
suddenly decide to leave the project. You then end up with a flurry of re-
adjustment and the project team often gets bent out of shape in the process.
Portland color varies from batch to batch and if the Portland is not all
purchased at one time on the project then you can anticipate variations.
Solomon colors are not always easy to come by as the distribution and sales
process is erratice from year to year. It is not like we are buying the
material by the truckload either -- which means that we have no leverage over
any aspects of sales & distribution. We have had about 1 dozen bags of a
brownstone tint sitting on our shelves for ten years. Over the last few years
we have had increased pressure to make invisible matches to various materials
and, fortunately, we have in NYC available off teh shelf dry color tints in a
multiplicity of variations and when needed we custom mix our own colors, often
using five or six separate tints. What we particularly attempt to avoid is the
design penchant to use more than one color of material to match variations on
a facade. I think there is an idea that since paint manufacturers can match
any color that restoration masons should be able to do it as well. Such a
narrow focus of color matching may be economic on small *jewel* projects, but
certainly not on larger buildings.
We have had problems in the past with lime leaching. Our policy is to not do
composite patching or sensitive repointing (as opposed to a warehouse) if
night temperatures are below 40 degress, regardless of any fantasy that
weather protection and supplemental heat may obviate the outcome.
][<en Follett
][<en Follett
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