Waterproofing Segmented Bowl

[Steve Eure]

I have been turning several segmented bowls the last few weeks and have had a request for a salad/fruit sized bowl from a pastors wife that would be used to hold water for baptisms.
I generally use my own mix of tung oil, MS, and spar varnish on them with very good results. I am wondering if that would be sufficient or should I use another type of finish. Maybe several coats of poly over the mix.
Any thoughts or suggestions?
Thanks,
Steve

[Robert Marshall]

The only finish that I can imagine being really waterproof is epoxy. A bucket is just a "reverse-boat," and boats are commonly finished with epoxy because it's so good at keeping water out, which is pretty much the same as keeping water in. Carefully done, epoxy can look good and be waterproof. You'll need to sand to very high grit levels, and probably polish it as well.

[John Beaver]

For that purpose I agree with the epoxy finish.
I would also recommend using Titebond 3 for it's waterproof qualities.

[Marvin Hasenak]

I generally follow the instructions on this link. http://www.epoxycraft.com/thinning-epoxy-best-practice-reducing-viscosity-west-system-epoxy/

I am lucky in the summer time I can just sit the bowl or whatever in the sun inside of a black trash bag. Wait a few minutes and then tart mixing my epoxy and the bowl will be hot enough. I use throw away brushes to spread the epoxy.

[Steve Eure]

Thanks for the information. I went to West website for more info and then to dealers of their product and got sticker shock. Are there any less costly alternatives to West products? I don't think my client will want to spend that much extra for 1 bowl.

[Dave Bunge]

Another option would be to find a waterproof (glass or stainless steel) bowl of appropriate size and shape, then design the segmented bowl so that the waterproof bowl fits inside it. You would still want the segmented bowl finish to be water resistant.

That is how I recall most baptismal fonts in churches being set up...the vessel that actually holds the water is usually a stainless steel bowl inside the larger wooden font.

[Robert Marshall]

I believe you could probably get away with using spar varnish, IF the bowl is only wet long enough for a baptism, and is promptly and thoroughly dried, thereafter.

I would worry if it was put aside with water in it, and forgotten for a few hours or a day or two. Once the water finds a tiny way in, there's no stopping it. Wood expands, tiny opening expands, etc.

[Paul Williams]

West System is good stuff, but I don't think it is necessary, nor do I think you need too much. Go to Hobby Lobby or similar retailer and look for any clear epoxy laminating or encapsulating product. It doesn't take much to apply one coat to the interior of one bowl. Use your normal finish on the outside. Apply it carefully and do not sand, but accept the gloss finish you get. Do not thin, you do not want it to run.

Regarding the earlier comments about thinning epoxy, we built a experimental airplane out of epoxy in 1981. We kept the shop at 80 degrees and the epoxy pump stored in an insulated case with a 100 watt light bulb behind it. Heat really does thin the epoxy. It also makes it set faster so don't think you are going to thin 5 minute epoxy this way. We did not have problems with overheating as long as it was spread out soon after mixing. A mixing cup with left over epoxy would generate heat, as would a layup that involved a dozen or more layers of epoxy. That type of layout would require fans to dissipate the heat.

[JohnC Lucas]

I have used System 3 epoxies from Woodcraft with good results. Still not cheap but you can buy it in smaller quantities. I'm a West System fan and once you spring for the larger containers you find all sorts of uses for it. Look into the slow turn curing process. Basically you use a very slow rpm motor and rig up a way to hold the bowl. Spread on the epoxy and let it rotate which evens out the epoxy. Don't have time to look for good videos or even watch this one all the way through but it appears to have the general idea.
https://www.youtube.com/watch?v=C9g_GRTobUg

[Alex Zeller]

I've done a little boat building and have used West Marine brand. It's good stuff. I bought it by the gallon and I can say that a gallon is a lot. For a small bowl you could probably buy what the local hardware store has in stock. The biggest issue would be the learning curve. You will want it to be dust free, even a speck will show up as a bump. I would brush it on as thin as I could covering just the inside. I think I would put on several coats so I could learn. The first one would take more epoxy since it would be absorbed into the wood but the next coats should use very little. If you build it up some you should be able to chuck the bowl in your lathe and use fine sandpaper to smooth out the epoxy and possibly even get a satin finish. If you think this would be a one off project then it might not be worth doing multiple coats but if there's a chance that you could be doing more then I would worry less about making a profit and more about learning.

[Rob Price]

I’ve used pro marine crystal clear bar top epoxy from Amazon and envirotex as well. Cheaper than west systems.

West systems are for for the most extreme evironments, constant water contact, extreme temps, etc. I don’t think you quite need that level.