suggestions for cheating, carving a set of ionic volutes for column capitals

[optimist]

I scarfed up a set of 4 fluted columns for my deck off of craigslist a while back (yay!) But, they didn't come with capitals (boo!). Finding the prices for capitals of the size I need to be kra$y, I've decided to try to make them. I think I've got most everything figured out, except for an important detail. I need to build 8 (front + back) volutes. Which is basically just the scrolly-looking part of this (http://www.fotosearch.com/ECC116/01030018/). Roughly 26" X 11" and ~ 1 1/2" thick. Luckily I have 4 columns with capitals like this from which to copy. The detail not obvious in the drawing is that the "flat" part of the scroll isn't flat but dished out round about 1/2" deep at the deepest and, of course, gets shallower as the gap gets narrower. I assumed I'd hand or rotary carve this detail until I actually tried to…granted I tried in a pine scrap, but it taught me that I have no where near the patience or talent necessary to do 1 this way, much less 8 - at least not without cringing every time I walk by them. So, I'm looking for cheating suggestions. Since it will be painted after all, my only thought is to create a pattern of the volute, route out the "gouge" 1/2" deep and square edged, and fill back a dished gouge with bondo wood filler. Then shape and sand the bondo since (I think) it will be easier to shape than any wood because there's no grain to deal with. I did one sample this way (except I didn't go a full 1/2" deep) and found that the bondo was still very hard to sand which resulted in rounding the wood detail wherever I didn't want it. So, not a perfect solution. Less hardener in the bondo will give me longer working time, but still, shaping it is tricky and I have no tricks up my sleeves. Before I go whole hog on this, I thought I'd stop and ask for advice from the experienced folk here.

Is bondo the right choice? Is there something else easier to work and still weather-resistant once painted? Or is there yet another way to do this I'm not thinking of?

 

[Mark Gottesman]

If you have an item that you can pull a cast from then do so. Use plaster of paris for negative and cast a thin ovelay panel with the volute in white portland cement with fiberglass fibers mixec into it. Attach them to a base that will fit on your column with marine epoxy and paint with a thick paint . I think that would do it.

 

[PeteM]

I'd make them all fiberglass.
Lots of how-to videos on YouTube.
https://www.youtube.com/watch?v=TFdDg9kwKrM

 

[Phil S]

If I had to make eight that all look alike, I would carve one out of blue foam and then make a mold using any of a variety of casting compounds - liquid silicone rubber works well. Once you have the mold you can make eight quite easily. There are many compounds that will work, my experience is with pourable medium density expandable urethane foam

 

[optimist]

All great suggestions. Not sure I can cast one of the caps that I have w/o taking it apart so taking the time to carve one "perfect" one and casting it sounds like a plan. I've no experience with blue foam, but that's intriguing. If I can find any locally I might take a stab at that. I'm also liking the GFRC idea since if I were to buy capitals they'd likely be GFRC, so that's a natural fit.

Thanks guys.

 

[Phil S]

The blue foam should be available from any home center. The blue is made by Dow and comes in 4x8 sheets that are 3/4, 1, and 2 inches thick. You can glue it together to create ant thickness you need. There is a pink foam that is also very workable. Avoid the white foam

 

[Jim Wallace]

I've done some salvage work and all the capitals I've come across were cast plaster of paris. Painted, you can't tell it's not wood of course.

 

[optimist]

Jim, that's really interesting…I disregarded PoP since I assumed it would eventually disintegrate in exterior use, even if well-painted…but a little googling says that adding an Acrylic Polymer or resin in addition to or instead of water to the plaster makes it at least more waterproof. That's got to be more cost-effective than GFRC, probably lighter and maybe less-complicated. I'm willing to bet that if I picked at the capitals on my front porch columns I'd find plaster…I definitely can't swear they're wood.

 

[Jim Wallace]

Joel, Not only are the capitals painted, but they sit on top of the columns next to the roof where they won't get much weather. I'll bet that if you search online you can find a source for ready-made molds so you can pour your own.