Rudy:

Speaking/writing as a conservator who has used Acryloid B-72 for a  
number of years, this is not an application that I would consider it  
for.  B-72 is an amazing resin - very stable & very versatile - it is  
used as a consolidant, adhesive & coating by conservators.  It has a  
very high glass transition temperature which makes it a great adhesive  
in hot climates (I used to work on excavations in Jordan where heat  
tolerance was an issue with any of the ceramics I repaired).  Frankly,  
I consider it an indoor material - I don't know of anyone using it  
outside.  If the sign were inside I'd say consider it but not outside.  
  The other issue with B-72 is the gloss - it can be pretty shiny.   
Maybe they need to look at what is being used for traditional  
wallpaintings?

Sue Maltby, Conservator
Maltby & Associates Inc.


Quoting Rudy Christian <[log in to unmask]>:

> Well folks, here's another inquiry that came to PTN that seemed best  
>  mangled by all the Pinheads, not just this one. My suggestion would  
>  be to build a timber frame enclosure over it and keep the rain and   
> sun off!
>
>> My name is Sondra Carson and I am a member of the Landmark   
>> Preservation Commission (LPC) in Fort Collins, Colorado. Currently,  
>>  we are discussing various options to protect a Coke-a-Cola sign   
>> that was painted on a brick wall.  One of the options presented to   
>> the LPC included using Acryloid B 72 to prevent any further   
>> deterioration of the flaking paint. I have thoroughly read   
>> Preservation Briefs 1 & 2 published by the National Parks Service   
>> (published circa 2000). Based on these publications, it is my   
>> understanding that water repellents are only indicated as a means   
>> to control deterioration or dissolution when water penetration is   
>> problematic after repairs have been made to make it watertight.
>
> Even though these water repellents are relatively vapor permeable, I  
>  couldn't find any literature/journal articles that suggest the   
> primary indicated use of Acryloid B72 as a means to preserve a   
> historic painted advertisement. In essence, I've been looking for   
> the effects of water repellents layered over lead based paint on   
> vapor permeability on a masonry wall. I'm guessing it would decrease  
>  but I don't know how drastic.
>
>  So, my question... Is Acryloid B72 (or any other water repellent)   
> ever indicated as a protective coating over a historic lead based   
> paint advertisement on an exterior masonry wall? I’ve been told   
> Acryloid B72 is considered a new and safe water repellent being used  
>  in the conservation of painted advertisements but I am unable to   
> find any research studies/literature/journal articles that can back   
> up this opinion.
>
> I would deeply appreciate it if you could shed some light on this for me.<
>
> Suggestions?
>
> Rude E
> Helping put the *Shine* on HP
>
>
>
>
>
> --
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>
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>

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