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My steam box for bending has mold

1K views 16 replies 10 participants last post by  Trevilo 
#1 · (Edited by Moderator)
Hi Jocks,

I bend wood using a steam box. After I use it the moisture causes mold to have a fertile ground to grow.

Does anyone have suggestions for how to kill and clean the mold out? It is a 1ft by 1ft by 8 ft box. The opening is only on one end so I can not reach the majority of the box to clean it out.

Thank you for your advice.
 
#2 ·
Bleach 10:1 is always effective, but for me I'd go with an ammonium quaternary sanitizer just because it's a bit safe and I have good sources from my trade. Best bang for your buck would be these Am-Quat tabs, ver commonly used in hand ware washing applications.

Biggest key would be to leave the box open and if possible have a fan run into it until completely dry.
 
#5 ·
I think that I would make it out of another material beside wood. Unless you can get it dry quickly afterwards, the mold will be a continual problem. Pressure treated wood might not mold as badly I suppose (copper is one of the substances use to PT wood). I use a section of metal duct for my steam box. I simply block the ends with towels and wrap towels around it to retain the heat better. I keep saying that I am going to find or make some plugs for the ends but I never seem to get around to it. You could use a double walled chimney pipe and wrap some sort of insulation around it to make more efficient. I made a couple of feet to sort of cradle it while in use so it doesn't roll and I just stand it up in the corner when not in use.
 
#6 ·
Start at the beginning. You have mold growth because you have a water problem. Stop water from laying in the chamber, and your mold problem will stop as well. This is why a steam chamber needs to have at least a hinged top, so it can be open, and allow the wet to dry when not in use.

Bleach seems to kill mold, but doesn't really, you still have plenty of spores after bleach, that to say you killed it is incorrect.

Vinegar will kill most forms of mold, BUT not all forms of mold, but is cheap enough you can spray some on the wetted wood, and it likely will kill, at least better than bleach.

The Copper mentioned above works great, Just know it can trap the water underneath it, and on the woods surface, so you swap mold for rot. Either you need to completely cover the entire interior, or my suggestion is to use strips of it low, and on the sides of the chamber, but not the bottom, and what is behind it will drip down, and be allowed to dry if you have a chamber with an open top.

The other fix, it to swap wood for a large enough diameter PVC pipe, rot isn't an issue there, and Vinegar will take care of the mold.
 
#7 ·
How does the PVC hold up the the heat? I went with the metal duct because I read that PVC max temp is around 140°F and I didn't want to worry about it sagging over time since the temperature of steam is whatever your local boiling point is.
 
#10 ·
That stove pipe would be perfect and at current plywood prices a fraction of the cost, especially since you already have some on hand.
 
#12 ·
Steam is 212* Most folks use a wallpaper removing steam generator from Rockler to build a unit. Those using PVC usually use PVC end caps to cap the ends, and place any attachment for the steam tube. In doing that if they were left without some holes along the PVC you would have a small explosion from trapped expanding steam. Those holes decrease pressure, and also allow the PVC to work fine as a chamber. It's normal to use the holes to both decrease pressure, but to also support your bend wood on dowels inserted through the holes. They keep the bend wood out of the puddle you would have otherwise, at least until it blew up. PVC is probably used in at least 1/3 of new build chambers, Still wood is used the most. Pipe for a chimney is pretty light to support much weight inside it, not to mention a lot of folks can't seal it worth snot.
 
#13 ·
Hi all, Thank you for the many suggestions.

It seems for the existing box a vinegar solution is a good idea. Would residual vinegar have possibility of staining the white oak that I steam? I think vinegar causes white oak to grey/blacken.

The longer term solution is to make a steam box from metal.

Did I follow that correctly?
 
#14 ·
I don't think that the vinegar will cause a problem. You may be thinking of the vinegar and steel wool solution used to ebonize wood. It is the iron in the solution that causes white oak to change color.

BTW, most white vinegar is only 10%. If you look for horticultural vinegar in a nursery that sells organic pest control, you may be able to find the stronger 20% stuff. It is used as a weed control. I think that pickling vinegar may also be stronger.

Anyone ever tried denatured alcohol on mold?
 
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