Humidors, plastics and hooves

[Ben Fleis]

I am working on a project that has an integrated humidor, but this is the first that I will have built. I understand that glues can have considerable impact on the cigar flavor due to a lifetime of off-gassing. Would hide glue be an acceptable choice here? Since it's not fundamentally plastic, unlike PVA and most modern glues, it seems like a safe choice.

I can approach this in a couple ways -- meaning that I could only glue my miters, and other joints that aren't directly exposed to the cigars. My design that could be made entirely glue-free, or mostly glue free, perhaps using hide glue for the inner spanish cedar lining.

Also, for the purists who may be in the know, what are the thoughts on exterior finishes? Does the off gassing of the exterior matter in general? In my case the humidor is actually a box that is drawer fit, so it wouldn't have a lot of breathing room of its own, leading my to think that shellac might be the safe alternative a la hide glue.

Any thoughts on this stuff would be appreciated, or pointers to good resources. A couple mags have done articles on humidor construction, but I haven't found anything pertinent to these details so far.

Thanks.

-b

[Wayne Bitting]

bump...

Ben - I'm interested in learning about this two. After my crib is built next on the list are a couple of humidors. I have my own questions to add.

Is hide glue okay to use on the inside for the liner? I'm planning on hammer veneering the outside and to prevent warping the inside too. Will the high humidity mess with the hide glue over time?

Wayne

[Cliff Rohrabacher]

Such an interesting question.

My first response was that the glue once cured, would not like be much of a concern. Then I got to thinking about humidity and time and - - well you never know.

There are old school glues with no odor such as rice glue.

Zap-o is supposed to be an odorless CA glue.
http://www.rcmarket.org/zap-o-odorless-pr-21052.html

You can also do the Cedar lining as a finger jointed unit held together by only the friction of the finger joints with the base locked in a little groove.

[Jamie Buxton]

Why do you think "non-plastic" glues would be odorless? Consider tobacco. It is certainly non-plastic, but it has an odor.

Hide glue has a reputation of not liking high humidity. It grows mold, and fails prematurely.

[David Keller NC]

Regarding off-gassing of polymerized glues (modern glues) - there's very little off-gassing from PVA (polyvinylacetate) and CA (cyanoacrylate) glues - the point of being nearly undetectable after a couple of weeks.

Epoxy and resourcinal (ie., plastic "resin" glue) is a different story. The will off-gas appreciably for a month or so, though that diminishes greatly over time.

Regarding hide glue - hide glue, if properly applied as hot hide glue, will withstand quite high humidity levels and still retain its bonding properties over hundreds of years. It will not support mold growth so long as it's dried (dissolved hide glue's a different story - it molds after about 3 days in a glue pot).

Regarding an exterior finish - this matters little from the standpoint of VOCs migrating to the interior. Once thoroughly cured, most modern finishes don't off-gas appreciably, though they do while curing. Shellac is a perfectly appropriate finish if the piece isn't going to be subject to alcohol spills and high wear (it would not be a good finish for a bar top). That said, I'd say this is a choice best left up to the customer's preference, though I'd steer them away from polyurethane if possible.

[Rob Sack]

I would also recommend not using hide glue, even if it is resistent to the humidity. Yellow glue is a much safer bet in my opinion and leaving the glued up pieces in the open air for a couple of days will take care of any possible outgasing. When making humidors, care needs to be taken in the case construction. The interior is unfinished Spanish Cedar, and the exterior is usually finished, which creates an unbalance panel. Having been making humidors of all sizes for many years, I have seen the panels cup due to the unfinished interior surfaces, which are exposed to consistently high humidity, and the sealed exterior surfaces, which are usually exposed to much lower humidity. This is a recipe for disaster and the construction of the case work needs to counteract this.

[Ben Fleis]

the variety of responses highlights the lack of solid information out there regarding glue off gassing, and the true long term strength of hide (or other purely organic glues) in a humid context.

Although I have heard from others that PVA does continune to slowly off gas over time, there seem to be many professional humidor makers that use PVA, so my guess is that if PVA is a real issue, only the true aficionado would be capable of noting the difference. Hide glue seems to be safe so long as it's done right, but I am inexperienced so far, and getting it right might be not worth the risk.

Instead of all this headache, I've decided to take a completely glueless approach. I am constructing the box with sides of qs american sycamore, which will be joined with half-lapped dovetails, and pins from the top (and bottom, of the top). The pins shifting loose may be a concern over time, since they will live in direction of expansion... I might bail and glue just the pins, but I think if I do it carefully (ie, sufficiently tight in the dry winter), I should be ok. The top and bottom will both be framed and pinned spanish cedar panels. I considered sandwiching spanish cedar along with a more visually pleasing wood on top, but decided to keep it simple in this case, since the cedar won't be visible until the case is out and open. Inside the case will be mitered, press fitted thing spanish cedar lining. Easily sanded/replaced/etc. since unglued. Again I could bail and go with a dot of glue on each, but will try it all without.

The sycamore will likely get a thin shellac coat, and the cedar will go unfinished.

My hope is that going completely glueless actually provides some bit of appeal to the purists out there, since it means literally taking no chance on chemical interference.