Bondo (auto body product) ok to fill gaps in ornamental plaster?

threeapplesDecember 18, 2012

We have a large ornamental plaster medallion on our dining room ceiling that came in two halves. There is a slight gap where the halves meet and the fabricator said we should just fill it with plaster and sand down. Our painter wants to use Bondo, a product our whole crew seems to favor. I know it can be sanded, but wonder if it will look different than the plaster over time. Thanks.

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drewem

No offense, but I am wondering why do you happen to question every little detail? Do you not trust your crew? Did you research them? I can see on big items like brick, but trim work? Again, no offense, just wondering.

    Bookmark   December 18, 2012 at 10:10AM
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brickeyee

Just use EasySand with a bonding agent (even diluted Elmer's white glue works well (half glue, half water, wait till it gets tacky to plaster).

It makes it very likely you will have to paint the trim.

I would have held out for a single piece casting.

This post was edited by brickeyee on Tue, Dec 18, 12 at 10:14

    Bookmark   December 18, 2012 at 10:13AM
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live_wire_oak

If it's painted, it's not a big deal at all. Bondoaka polyester resin is a great product and fairly easy to use for all kinds of purposes, even by a novice. Just don't mix it too "hot".

    Bookmark   December 18, 2012 at 10:13AM
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palimpsest

The bondo would probably be easier to work with and perhaps stay connected better. I don't remember what they did with my plaster work. There are areas were you can see the joints if the light is right on the horizontal runs but some of these are joints between new work and 170 year old plaster.

I don't think the joint will be apparent in the medallion.

drewem, actually the crew on this project is doing a certain amount of stuff for the first time. Not exactly the first time ever but the first time in this way.

They are used to building McMansion style houses where variations in detail don't make all that much difference because it is all about general impressions.

This house is being built with a fair amount of historical accuracy in detailing, and in that sense there IS a right and wrong way, even when it comes to methodology, sometimes.

I don't know that Bondo vs. patching plaster is a big issue to be concerned over, but with a crew that has worked a lot with Fypon and very little with genuine plaster ornament and genuine built up wood cornices with site applied dentils or modillions, I think threeapples has some genuine basis for questioning details, particularly given some of the issues that have happened in this build from the very beginning.

I had a whole renovation project stall for an entire year because of a plaster restorer whose work not only had to be removed from the original work but whose work Damaged the original work. It took that long to find someone who was capable of doing the work, would undo someone else's work and then they needed to be available.

Brickeye, they don't make the medallion that goes on this ceiling in one piece, it's too big. (They being one of the few companies in the US that still makes plaster ornament). Neither of the two companies that I have worked with make something this big in one piece, and I've not seen this offered by anyone else.

This post was edited by palimpsest on Tue, Dec 18, 12 at 10:31

    Bookmark   December 18, 2012 at 10:26AM
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threeapples

Nobody makes plaster medallions in this size that are one piece.

    Bookmark   December 18, 2012 at 10:30AM
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drewem

Thank you palimpset. I was just wondering, because it seems like every single detail is questioned, and debated. It seems like she does not trust her crew. I wonder if she knew about the crew's inexperience with a custom house beforehand.

    Bookmark   December 18, 2012 at 10:31AM
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threeapples

Our trim crew is great and they have done a very impressive job, but they have never worked with ornamental plaster before. Few people in our area do. They have asked me for guidance because they know how important the details are to me.
Nope, I don't trust everyone on my crew, but the trim guys have proven they will work hard to get details that are new to them perfect because they seem to care about helping to fulfill my vision for this house.

    Bookmark   December 18, 2012 at 10:38AM
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palimpsest

drewem, I don't want to turn this thread into something else, but unfortunately sometimes you don't know about the capabilities of a crew until you work with them, and that can be too late.

My first contractor came with rave reviews, I saw pictures that looked good. The person who recommended him said "He can take a sketch from a napkin and build it!"

Unfortunately, that was true. The translation of detailed drawings was as loose as if it had been a sketch on a napkin. If you had a vague idea of what you wanted he could build you something nice. He could not, however, follow a plan, or maybe even really read or understand a complete plan. I went for four years without a kitchen unraveling the mess.

I definitely think there are some trust issues in this case as well, but generally, not unwarranted.

    Bookmark   December 18, 2012 at 10:43AM
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sombreuil_mongrel

Plaster bonds to plaster. Use plaster of paris, add a pinch of retarder, put in an icing bag (or mortar bag with a very small tip) and pipe into the gap.
Useless to attempt w/o retarder, because the P of P will set in the bag inside a minute or two.
As fond as I am of bondo, I would not use it on decorative plasterwork. I mean, to what end? Because it sets faster? (no) because it would be easier to shape? (no) because it would adhere the best? (no).
Casey

    Bookmark   December 18, 2012 at 10:36PM
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threeapples

Thanks, Casey. My instinct says not to use Bondo as well. These are delicate plaster ornaments that need to be treated sensitively.

    Bookmark   December 19, 2012 at 8:25AM
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lazy_gardens

drewem - "I wonder if she knew about the crew's inexperience with a custom house beforehand."

A crew can have lots of experience, but there's always some detail or details they will not have seen before, especially in a custom house's finishing details. There's little you can throw at the structural crew they haven't seen before because it's standardized and has codes, but interior finish has a gazillion variations.

Based on work I did in a house with real plaster molded details (fun to cast and apply and mold new ones!), I would use real plaster with a bonding agent to seal the gap.

    Bookmark   December 19, 2012 at 12:16PM
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threeapples

Lazy gardens, what type of bonding agent do you recommend?

Thanks.

    Bookmark   December 20, 2012 at 9:34AM
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lazy_gardens

We used Plasterweld or something like it - I don't remember because it was quite a while ago. They are all a PVA (polyvinyl acetate) blend.

Just don't decide that something else will work because you saw it on Pinterest.

    Bookmark   December 21, 2012 at 2:07PM
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lsst

We used real plaster medallions in our build and the installer used plaster and a bonding agent as suggested above to fill in the gaps.

We used a company that made the medallions as well as installed them.

Several years later and no problems. You can not see where they were joined.

    Bookmark   December 25, 2012 at 6:32PM
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lsst

We used real plaster medallions in our build and the installer used plaster and a bonding agent as suggested above to fill in the gaps.

We used a company that made the medallions as well as installed them.

Several years later and no problems. You can not see where they were joined.

    Bookmark   December 25, 2012 at 6:33PM
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