Hi All,
I just thought I would relay my recent experience removing red &
white paint from some used Rohn 55G. After looking at the available
options, I selected soda blasting as the method of choice. Soda
blasting is similar to sand blasting but uses a sodium bicarbonate
(baking soda) abrasive that does not harm the galvanize layer
unlike sand blasting (or so I am told). This seemed advantageous
since about 90% of my tower's galvanization was intact. The soda
is also environmentally friendly.
Last weekend I soda blasted 15 sections of tower. Equipment rental
was $200, material cost of eight, 50 pound bags of soda was $25/bag
and $50 of diesel fuel ran the compressor. Total cost was $450 or
$30/section.
The soda blasting worked as advertised stripping the paint but not
the galvanize except for a small amount of flaking adjacent to
rusted areas where the galvanize layer was very thin. It easily
removed the areas of loose surface rust.
Blasting a section of tower takes awhile since the legs and braces
must be blasted 3 times to remove paint the full 360 degrees around.
I averaged about 1 hour 20 minutes per section using the soda at a
very slow rate. You can speed the process by increasing the soda
flow rate but you'll use more soda. It is hard work and loud. In
retrospect, I would consider paying extra to hire someone else for
the task but if you don't mind hard work and loud noise you can do
it yourself.
Overall, I am pleased with the results. The next step is to wipe
down the sections with water and a little vinegar to remove soda
residue then spot treat the rusty areas with a coat of ZRC cold
galvanize paint followed by a coat over the entire tower.
Hope this is useful to someone - I certainly had a blast doing it! ;)
73,
Steve
--
Steve Miller N8SM millersg@dma.org http://www.dma.org/~millersg
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