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Forum topic by DocSavage45 posted 12-01-2018 09:36 PM 824 views 0 times favorited 14 replies Add to Favorites Watch
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9053 posts in 4008 days

12-01-2018 09:36 PM

Topic tags/keywords: question pine finishing

Hey LumberJocks!

Another problem that requires a positive solution.

When is a box not a box? When its a soap making box!

Client wants a box made by me.

Problem: 110 degree liquid put into and enclosed box to set and cool.

.1 internal temperature and moisture in an enclosed box, and durability?

.2 Would pine covered on the interior with epoxy and poly on the outside maintain equilibrium?

.3. Would cedar work better?

Since this is for a friend I plan to do some carving etc on the outside.


Your help is appreciated!

-- Cau Haus Designs, Thomas J. Tieffenbacher

14 replies so far

View EricTwice's profile


248 posts in 1699 days

#1 posted 12-01-2018 09:53 PM

I find that wood must be allowed to move.
If you cover the inside with epoxy you are asking for trouble. (although this might not be a big deal with pine)
Eastern red ceder has a very small movement coefficient and would be a good choice (it’s also easy to carve)
I would finish with linseed oil (it is not as durable but easy to repair, other finishes will not hold up long either but must be removed before they ban be restored, also oil does not peel)
Also consider that no finish is a good option for a soap mold

-- nice recovery, They should pay extra for that mistake, Eric E.

View CharlieK's profile


605 posts in 4959 days

#2 posted 12-01-2018 09:54 PM

Wow, Tom! I don’t know anything about soap making. 110 degree liquid, so would it be like filling the box with hot water? How big will this be? I think white oak would be better than cedar, but more difficult to carve. Interesting question!

-- Adjustable Height Workbench Plans

View Redoak49's profile


5328 posts in 3154 days

#3 posted 12-01-2018 10:02 PM

I think white oak would be good with loose finger joints on the corner. Clamp sides, pour in soap, cool and take box apart.

View Andybb's profile


3324 posts in 1769 days

#4 posted 12-01-2018 10:04 PM

Disclaimer…This is just me thinking aloud.

1. Well, 110 is not much warmer than a 104 degree hot tub so it’s not an extreme environment IMO. More like luke warm. Hot coffee is more like 200*.

2. I’d consider Total Boat Penetrating Epoxy. Maybe 2 coats to insure a good seal or that then a coat of regular epoxy. (something that flows)

3. People make saunas out of cedar. (maybe pine too)

Would you even need to seal the inside? Titebond II and butt joints would have no problem with warm water. Those cedar saunas are bare wood. Maybe some wax just to keep it slippery assuming this is a mold that the soap will come out of when it’s cool and hard. Sand the inside to 400 grit and apply a coat of wax.

When you say “equilibrium” what do you mean? (don’t really know how to make soap) Just waiting for it to cool off?

Don’t know if I’d apply anything like a sealant on the outside with heat emanating from the inside, but that’s just a swag. (sophisticated wild ass guess). I think you’d not want anything that could retard the delta H.

Is this a fancy box that needs to look like a work of art or just a mold for making soap?? Does it have to be wood? If not then I’d consider HDPE. You can make that from milk bottles. HDPE soap molds

I guess I’m not sure if it has look good or just be functional. Another option if it’s just a mold is the silicone mold kits we use for casting pen blanks. Soap wouldn’t stick to that and it bends like rubber.

Naturally there are tons of soap making forums. One option I saw was just using a piece of saran wrap in the box and pouring the soap in. Then, no sealing necessary.

-- Andy - Seattle USA

View Ripper70's profile


1379 posts in 2074 days

#5 posted 12-01-2018 10:10 PM

In this instance, Google is your friend. There are a few examples with a silicone liner that look pretty slick.

-- "You know, I'm such a great driver, it's incomprehensible that they took my license away." --Vince Ricardo

View BFamous's profile


344 posts in 1286 days

#6 posted 12-01-2018 10:14 PM

I’d question why it’s being made out of wood? Seems like a poor choice from the start…
I used to do a lot of molding, and silicone compounds would be much more appropriate and also provide mild flexibility in order to get the soaps out of the mold… If the desire is a carved design, I’d say carve the design in a block of wood to look exactly like the soap should look (instead of the inverse), then seal it and create the silicone cast around that piece.

-- Brian Famous :: Charlotte, NC ::

View a1Jim's profile


118163 posts in 4743 days

#7 posted 12-01-2018 10:54 PM

I don’t think it’s necessary for 110 degrees but Ipe is fire rated the same as masonry products, but I think it would be hard to carves.


View DocSavage45's profile


9053 posts in 4008 days

#8 posted 12-01-2018 11:09 PM


Normally I’d address each suggestion individually,

Ripper thanks for that google page! Brian I did suggest soap molds on amazon. But she wanted something special made by me. Not making anything on this. If I were making soap, and I’m not I’d be as functional as possible.

Charlie thanks for the ideas. AndyBB lots of great suggestions will check into it. Like a wooden bathtub, but enclosed. Going to be a bit fancy!

Redoak49. Don’t think she would want to do the extra steps.

Eric E might play with the cedar but I have to make this a low maintenance box.

Jim don’t have any. LOL!


Getting a LOT of snow.

Gotta go!

-- Cau Haus Designs, Thomas J. Tieffenbacher

View Andre's profile


4624 posts in 2971 days

#9 posted 12-01-2018 11:12 PM

Why not make it like a cooler? Plastic or Metal box inside of another Wood Box, at 110 deg you wouldn’t need a lot of insulation, 1/2” would work to prevent most of the heat transfering to the wood.

-- Lifting one end of the plank.

View DocSavage45's profile


9053 posts in 4008 days

#10 posted 12-01-2018 11:25 PM


Good idea! Specific requested dimensions for soap size might make that difficult. Thanks.

Going out to shovel the walk to the shop.

-- Cau Haus Designs, Thomas J. Tieffenbacher

View bondogaposis's profile


6000 posts in 3517 days

#11 posted 12-02-2018 12:29 AM

I made a soap mold out of MDO for a commercial soap maker. No complaints so far. I varnished it with Ply.

-- Bondo Gaposis

View Andybb's profile


3324 posts in 1769 days

#12 posted 12-02-2018 12:38 AM

AndyBB lots of great suggestions will check into it. Like a wooden bathtub, but enclosed. Going to be a bit fancy!

- DocSavage45

OH. Then forget my silicone & HDPE suggestions. Good luck. Post some pics after you’re done.

-- Andy - Seattle USA

View BuckeyeJohn's profile


14 posts in 1296 days

#13 posted 12-02-2018 01:34 AM

Made some for a friend’s wife and a sister-in-law in- law, used half inch ply. They used was paper as a liner.

View DocSavage45's profile


9053 posts in 4008 days

#14 posted 12-02-2018 02:50 AM

Thanks, Bondo and Buckeye for your suggestions.

Purchased the Total Boat Penetrating epoxy that Andy suggested, as it seems that might work in the simplest way with woods on hand and according to the client’s request.

-- Cau Haus Designs, Thomas J. Tieffenbacher

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