Lager-safe shelf needed

[stephelton]

I'm building a fermentation chamber that has 3 cabinets, each about 23" x 23" and ~3' tall. Since these chambers may potentially be used for very cold lager temperatures, they need to be moisture and rust resistant.

So, in short, I'm looking for the cheapest shelf capable of holding up to 20 gallons (160 lbs or so) without significant bowing.

I've looked at various plastics, such as polycarbonate, but this could cost me well over $100, and this project is already well over its original budget estimate.

I'm pretty sure wood would be a bad choice since there will be a lot of condensation, unless I can treat/coat it with something to protect it. Likewise, metal would rust and would be difficult to cut to the shapes I need.

Any thoughts?

You can read a bit more about my fermentation chamber on my blog at http://blog.stephenashelton.com/2009/08/01/fermentation-controller-test-run-1/

Also, here's a pic of the cabinet that's partially built, to give a better idea of where I'm headed (I've changed my plans a bit since I wrote the above post):

The idea is that the platform would lay on top of the 1x4's at the bottom.

 

[goose_on_fire]

Wood's not a bad idea at all, properly treated.

I'd use 5/8" or 3/4" hardwood plywood coated in something like System 3's Clear Coat. It will completely waterproof the wood, provided you do it right. It's not too expensive, woodworking websites carry the 12oz. kit (enough to do 50 square feet) for about $30.

Most epoxies will do you well enough, I just happen to like that stuff.

 

[dkp]

You might also check into MDO plywood. I understand some states use this ply for highway signs.

 

[stephelton]

Thanks, these sound like much more economic ideas.

 

[ThreeDogsNE]

I can't tell where you are to know if there is a Menards nearby. My local Menards often has 3/4 inch lauan underlay plywood on sale at about $28 per sheet. While not officially marine grade, it should be pretty water resistant even before you treat it.

A water based polyurethane varnish should seal any plywood you choose well enough to withstand water contact. The lauan should give a harder surface and core, less likely to dent to breach the finish. Hardwood plywood usually just has a very thin veneer over a softwood core. One good ding and you're through it. If you go that way, or with plain plywood, I would use a penetrating oil finish, and give it several days (if not weeks) to offgas before you close it up.

Any wood spanning 23 inches will likely deform noticably under 160 pounds of load. An edging strip on both faces would help quite a bit. If you have a table saw or access to one you could rip a few 2 inch widths of the plywood, and glue and/or screw these to the front and back fairly easily. Think floor joists.

I'm sitting in my wood shop posting this one. It's been a hobby of mine longer than I care to admit.

 

[Catt22]

Additional support under the shelves would allow you to use thinner and less expensive wood for the shelf. I'd run some more 1 x 4's (or even 1 x 3's) front to back at the shelf edges and one more down the center. Maybe cut some 3/4" rigid foam insulation to fit between the 1 x 4's.

I would simply use some good quality exterior house paint to seal and protect the entire interior and the shelves. Applying multiple coats would be best.

 

[northernlad]

I am not sure how much you need or how long you want this thing to last...
Go to your local Resataurant supply and price epoxy coated wire shelving. Most manufacturers offer at least 5 year warranties. They are rated for 800lbs per shelf especially if it is just 24x24

 

[ThreeDogsNE]

You could make a torsion box to give a very rigid shelf. Use 1/4 inch underlay top and bottom and put 1x2 strips edge on in between. Set the strips in a grid, put some wood glue on, and then tack down the strips with some brads. Flip it and do the same with the other side. Very stiff, pretty light, pretty cheap. The 1/4 lauan is $8 per sheet. The 1x2s do have to be straight.

Latex exterior paint is good for vertical surfaces that will shed water, but if water will be standing on it, I'd think twice. Oil based paint would be a safer bet for that. Oil based deck stain would also work well. Being cheap, I'd check out the miscolored deck stain at Lowes or Home Depot or the like, as those are usually sold for about $5 per gallon.

 

[goose_on_fire]

I'm going to respectfully disagree with some of ThreeDogs' points with two caveats: 1) My opinions may be rooted in personal bias rather than fact, and 2) I was considering aesthetics out of habit. Most of it's a matter of personal preference anyway.

I agree that a varnish will probably seal the plywood for this application, but an epoxy is going to be harder and actually resist any chipping better. I've used that mirror coat as a playing surface for a foosball table and it's held up beautifully. It's also going to be more wear resistant and easier to apply (no bubbles due to outgassing, and self-leveling flowout abilities (no brush marks or lips at the edges)). When truly waterproofing, say for outdoor furniture, I typically drench the wood in clear epoxy for water protection, then the varnish goes over that for UV protection. Since this is indoors, I'd skip the varnish entirely.

As far as the luan underlayment, I find it has too many gaps, voids, and fills to be useful for anything other than, well, underlayment, and it would take a lot of work to get it flat enough to even use for that under any surface that transfers flaws at all (thin veneer, vinyl, etc.).

Luan as it's usually sold is Philippine Mahogany, which is actually (or at least, used to be) a cypress. I understand that the definition of Philippine Mahog changes pretty often. It's kinda like Red Snapper in that regards-- you accept that it's "edible fish" even though it could be any of a number of species. Long rambling point is, cypress is really a pretty soft wood, and as underlayment is generally thrown on really crappy sub-plys with the intent that it's going to have glue and roughly six zillion screws holding it to the subfloor.

But there's also the point that I've never seen it in 3/4" thickness, so we could be talking about entirely different products

I do agree it should be supported, at least with some front-to-back joists.

On the complete other end of how I answered this the first time, you could *probably* get away with cheap CDX plywood and a ****load of Kilz Exterior, Waterlok, or similar primers. I'd just be worried about penetration over a period of years, especially at the endgrain.

I hope none of that sounded combative or argumentative, just voicing my experiences.

 

[Catt22]

You could make a torsion box to give a very rigid shelf. Use 1/4 inch underlay top and bottom and put 1x2 strips edge on in between. Set the strips in a grid, put some wood glue on, and then tack down the strips with some brads. Flip it and do the same with the other side. Very stiff, pretty light, pretty cheap. The 1/4 lauan is $8 per sheet. The 1x2s do have to be straight.

Latex exterior paint is good for vertical surfaces that will shed water, but if water will be standing on it, I'd think twice. Oil based paint would be a safer bet for that. Oil based deck stain would also work well. Being cheap, I'd check out the miscolored deck stain at Lowes or Home Depot or the like, as those are usually sold for about $5 per gallon.

I recently built a platform bed using the diaphram construction you described. Same principle only on a larger scale. There are only legs on the corners and no center support at all. It is amazingly rigid with no noticeable sag in the center even with two adults on it. The top and bottom is only 1/4" plywood with five 1 x 4 clear pine runners separating them equally spaced. Glued and tacked together with a brad gun. I am very happy with the end product. It would work very well for the shelves I am sure.

 

[stephelton]

Thanks again for the feedback.

I intend to add a couple joists; in fact, I was thinking I might use 4 in a tic-tac-toe board fashion. This will work well with my intention of doing some elaborate air circulation (I mention this a bit in my blog / see below.)

Since I've put so much time and thought in to this, I intend for it to last the duration of my homebrewing career if at all possible, so protecting the construction is pretty critical. It sounds like some simple epoxy will be sufficient to protect the wood.

// new subject

While I've got the attention of some experienced persons, I'll explain one of my latest ideas.

I'm thinking about, instead of using 2x 3/4" insulation panels on all sides of each chamber as previously intended, using a lot of expanding foam. The cost here would be similar, and I'd end up (based on R values) getting a lot more insulation out of it, since I'd be applying layers much thicker than 1.5".

The chambers are designed to hold 15 gallon plastic drums (recycled bulk malt extract containers) or 4 corney kegs. So I'm thinking I'll start from the very bottom and begin spraying my foam, a little bit at a time, and use various dividers and objects to "mold" the foam. I'll wrap the kegs in a garbage bag (or similar) and pad a bit so that the foam will mold to their shape. I'll do something similar with the plastic drum at the top (since it is several inches taller).

This technique would solve several challenges in my design.

First, as I mentioned, I want to cycle the air in a controlled manner to aid in accurately detecting the chamber temperature. This involves sealing the area behind the fan/radiator such that it's "inlet" is routed around the bottom; this will effectively "suck" the air through a hole in the bottom, up the side, and back out through the radiator. This would be a natural side effect of the expanding foam technique.

The second challenge is that I need to run coolant to each chamber. The lines need to be sufficiently insulated in order to prevent them from absorbing too much heat in any chamber (could cause headaches when I have a warm ale next to a very cold lager.) This would give me many more options here.

And lastly, as I would be filling in all excess space, this would help constrict airflow to where it is useful, and would maximize insulation potential.

Does this seem like a ridiculous case of over-engineering, or a good idea? I think the outcome would be attractive and effective, but might be more difficult than I anticipate.

 

[Catt22]

I'm thinking that you may want to put some more thought into the overall design before proceeding much further. The expanding foam stuff will be much more difficult to work with than you might think. Not that what you describe can't be done, but it's bound to be messy and very challenging. The other problem I forsee is having the chambers at much different temperatures for ales and lagers. That will complicate the project a lot. I would need to know more about what you are using for cooling and how you plan to control the temperatures in each chamber. I would put a lot of thought into both insulation and temp control. The rest will be relatively easy.

 

[stephelton]

I'm thinking that you may want to put some more thought into the overall design before proceeding much further. The expanding foam stuff will be much more difficult to work with than you might think. Not that what you describe can't be done, but it's bound to be messy and very challenging. The other problem I forsee is having the chambers at much different temperatures for ales and lagers. That will complicate the project a lot. I would need to know more about what you are using for cooling and how you plan to control the temperatures in each chamber. I would put a lot of thought into both insulation and temp control. The rest will be relatively easy.

Except for the foam part (the idea popped in my head last night), the fermentation chamber concept has been brewing for almost a year now. I've implemented and tested all of the temperature controlling and cooling portions, and have fermented 4 beers so far (using cardboard boxes as chambers!) I've given the project way too much thought, and I'm down to only a few outstanding items. I'm hoping to finish this all up as soon as I make up my mind and start picking up materials. If you care, I talk a lot more about the design in my blog (see page 1 for link).

In short, each chamber has its own set of thermometers, as well as its own pump and radiator. The controlling software will activate these as necessary to maintain distinct temperatures. A compressor removed from an old fridge keeps a tub of water-glycol mix cold, which is pumped through the radiators, over which fans blow to cool the chamber.

If I do proceed with the expanding foam plan, I should be sure that I've thought it through. I've used "Great Stuff" before, and it makes a big mess where it's not wanted.

 

[Catt22]

I have not read your entire blog, but I do remember seeing portions of it somewhere along the line. I am planning something similar using an air conditioner as the cooling source. Yes, the Great Stuff is amazing and it can also make an amazing mess. Your design appears to be sound. I like the individual radiator/fan idea. I have a fairly new in room air conditioner that I am about to disassemble for my refrigeration source. BTW, never buy an in room air conditioner to use for its intended purpose. They don't work well at all as they suck cold air out of the room and exhaust it outside. It never keeps up with its own exhaust output. I feel ripped off on that one, big time.

 

[stephelton]

I have not read your entire blog, but I do remember seeing portions of it somewhere along the line. I am planning something similar using an air conditioner as the cooling source. Yes, the Great Stuff is amazing and it can also make an amazing mess. Your design appears to be sound. I like the individual radiator/fan idea. I have a fairly new in room air conditioner that I am about to disassemble for my refrigeration source. BTW, never buy an in room air conditioner to use for its intended purpose. They don't work well at all as they suck cold air out of the room and exhaust it outside. It never keeps up with its own exhaust output. I feel ripped off on that one, big time.

The design works, and is well optimized around flexibility, but it's very expensive. If I didn't enjoy the engineering and learning new things, this project would definitely not make sense. I haven't yet tallied up the total cost (as I still haven't purchased everything) but I'm pretty sure I would have saved a buck by hunting for 3 used fridges and buying 3 temp controllers! Not to mention my time..

That said, I've managed to keep the cost of the construction materials lower than expected. The electronics added up a bit, but weren't bad. The radiator / fan / pump combos were actually some of the most expensive parts, at nearly $80 per chamber. I'm using parts designed for PC water cooling; there may be much more cost effective products that accomplish the same tasks.

I just put in an order at McMaster-Carr for, among other things, the expanding foam and some general purpose epoxy. The expanding foam is actually a lot less (less than half) the cost of insulation panels.

I'm probably going to use some fairly thin plywood for the shelf at the bottom, and use some joists as was discussed. That should be simple, effective, and most of all inexpensive.

 

[stephelton]

Here are the shelves so far:

And here's the duct that will direct the air (look in the left chamber):

I'm really hoping to be done by the end of this weekend! ... or close enough that I can begin using it.