[Greenbuilding] renewing a cast iron tub

[David Bergman]

John,

That's a terrific help. Thanks!

David

At 10:15 AM 7/29/2011, JOHN SALMEN wrote:
>Film thickness is good – about double what would 
>be on an enamelled (glass powder) steel object 
>(baking pan type thing).  The hardness test I 
>always thought was pretty cute as it refers to 
>pencil hardness – the hardness of a pencil that 
>would create a mark and goes up to 9H. 4H is 
>equivalent to an acrylic tub coating and 
>probably most gelcoat fibreglass.  Basically 
>powder coating is a paint (polyester and or 
>acrylic resins). It is just applied as a powder 
>and uses heat instead of solvents.  The ‘paint’ 
>film with powder coat is stronger because it 
>hasn’t been broken or weakened with solvent 
>holes – does that make sense? Since it is a form 
>of painting the skill of the applicator and how 
>good the shop equipt is becomes important – ask 
>if you can increase the film thickness as that 
>is a good indication of what they can do (typical powder coating is 2-3mil)
>
>Impact is blow that would break the film (but 
>typically you have to crush the substrate and 
>this is cast iron) – salt spray test is 
>corrosion and 1000hrs is pretty high for a 
>marine standard but basically meaningless as the 
>tub won’t corrode unless the finish gets totally 
>worn away from obsessive cleaning or scratched or broken.
>
>So I think you could say that the finish would 
>be roughly equivalent to a fibreglass or acryic 
>tub – not as thick probably but having a cast iron base compensates.
>
>Care would be equivalent to an acrylic or gel 
>coated tub – no abrasive cleansers and 
>waxing/buffing the top and sides is not a bad idea.
>
>From: David Bergman [mailto:bergman at cyberg.com]
>Sent: July-28-11 12:11 PM
>To: JOHN SALMEN; 'Green Building'
>Subject: RE: [Greenbuilding] renewing a cast iron tub
>
>Returning to this question from a week ago, I've 
>determined that the tub can be sandblasted and 
>then powder coated, and that it may make more 
>sense both environmentally and economically to 
>do that rather than replace it with a (good) new 
>one that won't fit as well as this one does. But 
>I'm still trying to work through the durability and hardness question.
>
>A finisher/powder coater I have worked with 
>previously tells me that the baking temperature 
>is about 400oF and that the finish has these properties:
>Film thickness - 1.5 to 2.5 mil
>Hardness (ASTM D-3363-92A)   4h
>Impact 160 in-lbs direct.Salt spray 1000 hrs
>
>Anyone know how to gauge that? What might it compare to?
>
>Thanks,
>
>
>At 11:16 PM 7/19/2011, JOHN SALMEN wrote:
>
>I’m sorry I was trying to be humorous (on the 
>dark green side) as well as a bit positive. I 
>like the notion of recycling a tub and the local 
>labour involved. On the practical side I have 
>had to design numerous bathrooms and you have to 
>look at the clients needs and expectations.
>
>To be fair to the client I think it depends on 
>the design and the expectations. The tub is an 
>artefact – even if it is renewed it will stand 
>out unless the overall bath design supports it 
>as the old object that it is and for that you 
>need the client to want the old tub. You cannot 
>make an old tub look like a modern tub – it will 
>be shiny but it will still be the old tub. 
>Unless the bathroom design can compensate or 
>make use of ANY potential defects in some 
>imaginable perfection - I would bring in a new 
>tub.  If the design and the clients interest can 
>support the old tub I would hazard that the life 
>of an acrylic or fibreglass tub would be 
>equivalent to a renewed powder coated cast iron tub.
>
>‘Neatnik’ clients I would further hazard would 
>probably be more comfortable with a new tub.  I 
>have had clients that simply were fanatics about 
>old cast iron tubs. I have had clients that have 
>purchased new cast iron tubs that have required 
>significant floor engineering – but these were 
>clients that actually took baths that typically 
>grew up with cast iron tubs and could not be 
>dissuaded .  Next to overbuilt v8 heating 
>systems tubs are high on the list of overbuilt 
>and underused items in a home that are part of 
>what I call ‘cultural design environmental 
>failure’ – similar to 3 way switches .
>
>Free standing cast iron tubs take a lot of hot 
>water to get to stay at temp. A lot of the 
>people that are addicted to this type of bath 
>run the hot water at a steady flow to keep the 
>tub warm – these are not people that I will 
>design a freestanding tub for (if I have any 
>influence) this person requires a 
>fully  enclosed tub designs where you can create 
>a fully foamed enclosure that will retain heat 
>for as long as it takes for them to relax and get out of the tub.
>
>So on my checklist for this  I would probably have
>-          Client needs – client education/advocacy?
>-          Long term energy considerations (hot 
>water usage will outweigh any other cost if 
>people actually use the bath – but most people 
>don’t take baths and the bath is a decorative object)
>-          Local employment – local supply?
>
>
>
>
>
>
>From: David Bergman [ mailto:bergman at cyberg.com]
>Sent: July-19-11 7:06 PM
>To: Green Building; terrain at shaw.ca
>Subject: Re: [Greenbuilding] renewing a cast iron tub
>
>At 09:37 PM 7/19/2011, JOHN SALMEN wrote:
>
>Actually there is nothing wrong with an old pitted cast iron tub complete
>with iron (or blood) stains - it holds water and if I have a bath I am going
>to either try to read a book (without getting it wet) or stare out the
>window. It is just not shiny and 'nice' looking.
>
>I agree in principle, but there are two 
>additional factors at work here. One is that 
>once the rest of the bathroom is renovated, the 
>dulled or pitted old tub is going to stand out 
>(and not in a good way), and the second is that 
>the finish of this tub has become very hard to 
>clean. Even if the clients weren't neatniks 
>(which they are), this would be a problem.
>
>
>Will it last? Will it be durable? - what are we comparing it to - a stock
>portfolio?
>
>I hope not. Stock portfolios have done pretty badly, no?
>
>More to the point, the conventional in-house 
>recoating treatments -- in many or most cases -- 
>often don't last long at all. Sometimes five 
>years or less. I would be looking for the 
>refinishing to last as long as the bathroom 
>renovation is likely to last. (25 years?) 
>Otherwise, it makes more sense to install a new tub while the walls are open.
>
>
>David Bergman  RA   LEED AP
>DAVID BERGMAN ARCHITECT / FIRE & WATER LIGHTING + FURNITURE
>architecture . interiors . ecodesign . lighting . furniture
>bergman at cyberg.com    <http://www.cyberg.com/>www.cyberg.com
>241 Eldridge Street #3R, New York, NY 10002
>t 212 475 3106    f 212 677 7291
>
>


David Bergman  RA   LEED AP
DAVID BERGMAN ARCHITECT / FIRE & WATER LIGHTING + FURNITURE
architecture . interiors . ecodesign . lighting . furniture
bergman at cyberg.com    www.cyberg.com
241 Eldridge Street #3R, New York, NY 10002
t 212 475 3106    f 212 677 7291  
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