I first need to know if the sealant is urethane or silicone based. If
silicone, has the stone leached "oils"? If so, you've got a big problem.
If urethane, I agree with your approach David. I think if I were to
repoint the joint, I would do some mock ups as soon as possible to see
how the mortar bonds. Is scraping enough or is grinding necessary?
Eric Hammarberg, Assoc. AIA
Vice President
Thornton Tomasetti
51 Madison Avenue
New York, NY 10010
T 917.661.7800 F 917.661.7801
D 917.661.8160
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-----Original Message-----
From: The listserv where the buildings do the talking
[mailto:[log in to unmask]] On Behalf Of David West
Sent: Wednesday, May 27, 2009 7:51 PM
To: [log in to unmask]
Subject: [BP] FW: [ASGLIST] Removing sealant from granite
Any thoughts or experiences to share on this favourite exercise?
David West
Executive Director
internationalconservationservices
53 Victoria Avenue
Chatswood NSW 2067
Australia
T: +61 (2) 9417 3311
F: +61 (2) 9417 3102
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E: [log in to unmask]
W: www.icssydney.com
sustaining your heritage
-----Original Message-----
From: David West
Sent: Thursday, 28 May 2009 9:50 AM
To: [log in to unmask]
Subject: RE: [ASGLIST] Removing sealant from granite
My experience on a larger-scale (in buildings) has not been positive.
I've seen various techniques attempted.
For the best chance of success, I see it as a three-stage process:
1) Cut away (with a sharp, preferably hooked, blade) along the
edges of the sealant bead as close to the granite as possible. Cut down
both sides of the joint, and then attempt to pull the entire bead free.
Fabricating a dedicated bladed tool to free the rear adhered surface of
the sealant bead may be appropriate, depending on the width of the
joint.
2) Scrape or abrade away the residue on the edges of the granite.
Generally this has been a manual scraping or 'picking' technique in the
situations I've seen it done (unless the joints were being refaced as
per stage 3 below). Whilst I have not seen it done, I wonder whether
there are suitable flexible abrasive wheels such as are used for
aggressive paint stripping (abrasive meshes) that might be effective in
removing the sealant (albeit probably rapidly consumed), given the high
abrasion resistance of the granite.
3) Preparation of the edge of the granite blocks to receive the
replacement pointing material. It is important to ensure that the
granite has a surface compatible with whatever is going to be used for
repointing - or the repointing will simply debond from the granite and
fall away within a relatively short space of time. It is this step that
potentially has the greatest compromises with regard to the
authenticity, originality and level of intervention with the monument.
There may be times when minor refacing of the edges of the granite
blocks is necessary in order to ensure a good interface with the new
pointing material. If this is the case, then it also creates an
opportunity for removal of the sealant via a more invasive joint
grinding technique.
Of course, the significance of the original granite blocks and arrisses
is a major determining factor here - what might be suitable on one
monument or building would be totally destructive on another.
David West
-----Original Message-----
From: [log in to unmask]
[mailto:[log in to unmask]] On Behalf Of
[log in to unmask]
Sent: Thursday, 28 May 2009 12:52 AM
To: [log in to unmask]
Subject: [ASGLIST] Removing sealant from granite
I have a granite monument with sealant in every joint, and I'd like to
get rid of it. Are there any removal methods that are faster than just
picking away? Sooner or later, I guess everyone gets a sealant project
and now it is my turn.
Thanks,
Judy
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