Official Luthiers Forum!

HI guys and gals! I'll try to make this brief, I work in a modelshop that I have full access to. It has a drill press, spindle sander, table saw, band saw, vacuum former, bridgeport mill and a paint room with a spraybooth.
Perfect workstations for building a guitar, with dust collectors hooked up to limit the dust and fumes.
Sounds perfect to start building, right? Here's my problem, it has no AC, and no windows to put an exhaust from a portable AC/dehumidifier unit. The shop only has a big roll up style door. And with the dust collectors and spray booth running most of the day, everyday.
The humidity in the shop has been between 60% and 70% for the past couple of weeks. I'm Getting the portable AC, but I'm afraid the cool, dry air will just be sucked out of the shop making the unit work too hard???
The shop and spray both are separated by a door, but together they have a total area of 450 sq. feet.
I think I've found a solution to my exhaust problem. I can hook it up to the spray booth exhaust and it should be fine. But I still think I'll have a problem keeping the shop cool and dry with the dust collectors sucking air out of the shop.
Here's my question, what stage in the build is the most important to keep the humidity low? I can limit the use of dust collectors and spraybooth during that stage, but not during the whole build.
This guitar is most likely going to stay in Southern California weather for it's entire life, and in a case. I don't anticipate any drastic changes in humidity, except when the Santa Ana winds come in and dry everything out.
What do you guys think? Safe to build?
Thanks for all advice!!

Bracing the plates is the most critical operation. You can make a box with a light bulb or some other mild heat source in it to store your parts in while not working on them. Warming the box will lower the humidity inside you still need to monitor it though and pick a time when the rh is about what your box is to glue then on. You should really shoot for no more than 45%. Once the box is together it won't be as big a deal, particularly in southern California. Thin plates of Wood can react very fast to RH changes, a few hours or less depending on the differences in humidity.

_________________
Jim Watts
http://jameswattsguitars.com

There are a lot of times of the year the humidity there is just right. I have built several guitars in southern cali. Jim is right you dont want to build over 45% there, when the Santa Ana winds come it will suck all that excess moisture out of the guitar and cause big problems. If you time it right just get the box closed in the right humidity.

Another alternative is to build a small space in the shop that you can control easily. Either just a space to store components in the right humidity or even a small working area with a bench. Don't know where you're at in So.Cal. but I grew up in San Diego out towards El Cajon; if I was still there I would go with the storage option and just work on the boxes and plates when the humidity was right. On the other hand I also spent 15 yrs in the Mojave desert and if I was still there I would go with the small working area with a bench.

_________________
Steve Smith
"Music is what feelings sound like"

This is the big shared workspace where we teach the guitarmaking woodshop class for the charter school. We're the first space on the left, and you can see one guitar leaning up against the wood rack. The other tops and backs were in those cabinets at the time.

When I started helping out last fall and realized the work in progress wasn't kept in a fancy climate controlled environment, I thought, oh the humanity, surely it'll all be destroyed. But . . . we've gone through fall, winter, spring, and everything's been perfectly fine.

Similarly, I haven't kept my work in a humidity controlled environment for the past couple years and haven't had any issues. I'm not sure how stable the humidity is here in the valley. Granted, I'm sure we don't have as many swings as you would nearer the coast.

Mario used to mention a method with putting things in a garbage bag. Does anyone remember it?

Are you asking whether you can build a guitar in Southern California without AC? If it helps, there is a company called Taylor Guitars in San Diego. They build quite a number of guitars that people seem to like. I've done their factory tour several times and never noted any form of climate control in any of the main build rooms. I would say don't do any glue up during a rain storm (will we ever get one of those again?) or a Santa Ana and I think you should be OK.

I don't remember Mario's suggestion to use garbage bags, but wouldn't vacuum storage bags be a more prudent solution for protecting tonewood from RH swings?

The most important steps WRT humidity control are bracing the top and back, and closing the box. Being a hobbyist, I usually just wait until the humidity is in the 20s for these steps. There are plenty of other things to do...

FWIW, I face a similar situation in that I live in an old leaky building where it isn't practical to leave the AC on. It's only used for really hot days.

You might consider making a dry box. This is simply a big leaky box with a light bulb inside. It can be made from an old shipping crate or something. The slightly warmer than ambient temperature inside makes the interior drier than the surrounding air.

I have a feeling vacuums and guitars won't mix too well...

_________________
The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

A dry box is a great idea! definitely going to build one.
Thanks everyone for your advice. Looks like no dust collectors or spray booth while I'm bracing and building the box!

I used a dry room and built guitars in uncontrolled condition, but only gluing in the dry room (the parts would sit for a few days before any gluing commenced). I have not had any problem.

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Tonewood Colin, you know, before it's made into a box. Why would you want to protect a completed box from RH swings, when you've built the body from RH equalised parts?
Anyway, my idea was to be able to store braced plates loose plates and bracestock at equalibrium in a non controlled area, without the need of having to re-acclimate them in your build area, come assembly time.

Thanks for the info in this thread. I too have a high humidity problem in my shop and no A/C. In the house I have A/C but never really need to turn it on. Hasn't been ran in several years so my interior environment is really no different. I've pondered ways around this problem and these ideas are a step in right direction. Thanks for posting and answering.

-j

450 feet is nothing for a dehumidifier handle. I don't think you are going to have any problems. Yes the humidity may go up when you are running the spray booth fans but will quickly drop back down to where you want it. AC is not what you want. You want a dehumidifier.

_________________
Michael F Smith
Goat Rock Ukulele
http://goatrockukulele.com

Years ago on the OLF a member posted that he was just finishing up the final set-up on a new build and was using a shop vac inside the sound hole to clean up things. A notable and honorable objective I would add....

What happened next is that his arm, shirt, and the vac hose all joined forces and restricted the sound hole enough to let the vac suck the top and back inward cracking the box.... Ouch... Since then I was sure to never develop a flabby arm.....

A couple of things to consider. Braced plates, say a top will move if there is no RH control. I once took a braced top that was built in 45% on my back deck with a drink to do some sanding and cleaning up the underside of the top. Within 20 minutes the top had nearly turned concave right before my eyes.... The RH on my back deck was only 55%.... So you can see that until the box is closed there is little to prevent the ravages of RH swings and this should have bearing on how you store you plates.

One poster on the OLF used to insist that braced plates need to be installed on the rim at once or stuff.... happens. Although this is not true if one maintains proper RH in the shop at all times the notion was held close because this poster did not maintain proper RH at all times. Wrong causation which is not hard to do with many things including guitar building.

Huss and Dalton braces plates well in advance of using the top on the box. It works for them because again they maintain proper RH in the entire shop at all times.

At the risk of being redundant...... again..... step one for folks who ask me about learning to build guitars is to secure a proper RH solution for your shop PRIOR to any building or even checking out that new killer band saw. This also means that huge shops though cool are going to take more to get the RH solution in place. More dehumidification, more humidification, and of course more heat in some seasons not just for we human bags of mostly water but so that finishes and glues can cure properly.

Some folks can make bag-building or a dry box work for them but again it only took 20 minutes for a braced top of mine to change shape once out of the RH controlled shop....

If you are coming to the conclusion that RH is important, there is no getting around it...., and it's not uncommon to have set-backs if RH control is not heeded - good because that's the truth - RH is important and again step one with guitar building in my way of thinking.

One more thing. We use RH manipulation to recover dried out instruments. In the last several months this has been about half of our work load fixing the hundreds of cracks that happened because of our record (for us) -22F winter and not enough humidification where the clients guitars were kept.

Part of the drill for us includes not attempting to set-up an instrument until it has been rehumidified and equilibrium has been once again reached in a 45% RH environment. Guitar tops rise and fall to varying degrees simply with RH changes and it can be so very noticeable that setting up an instrument before a stable, acceptable RH is reached will likely make the set-up wrong and problematic.

So my point is that even for final set-up or repair work RH is important. We can't fight Mother nature nor would I ever want to so we had better learn to understand it and possibly, very possibly you may find cool ways to make RH control actually work FOR you!

I'll add that maintaining a 45%ish RH and 72F temp is pretty comfortable for we humans as well.

Thanks a lot guys! Great info! I'm still looking for an AC unit with a dehumidification feature on it.
I've been storing my wood in a bathroom with a small heater going 24/7. It keeps the bathroom at 77° @ 52%. Not optimal, but better than keeping it in the shop.....

I don't know how a portable AC will work for you but I bought one that was advertised enough btu's to be suitable for a garage, it wasn't. I had a mason friend cut a round hole in the brick veneer for the exhaust hose and even installed a grill to keep the critters out. You literally had to stand directly in front of it within a couple of feet to feel any cooling. I put the portable AC away in the closet.
Next, I bought a big window unit and had my brother-in-law knock a big hole in my exterior two car garage wall, install a window, and the AC. It worked great and I should have done that from the start. My shop was every bit as comfortable as my house.
Now I'm of the opinion that portable ac's are more suitable for small, dark, well insulated bedrooms at night.

You shouldn't use AC with dehumidifier function unless you want your room to be -30F all the time.

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

The few times I've been to southern CA it's been like pristine beautiful every day. You might get away with it there but you would never get away with it in Virginia where I live.