Wednesday, July 4, 2012

Solar Dehydrator for Dyestuffs (or whatever)

It Dries!
It Dries Dyes!
A while back my electric dehydrator decided to fizzle out.  The fan stopped working, so while it goes round & round, nothing is happening.  On the 3rd day of trying to dry some sage, rosemary & cilantro (food), I about had a screaming fit & just shoved everything in paper bags to finish drying. 
Around that same time I saw a FB post of the prettiest garden box ever... turned out to be a solar food dehydrator.  Massively cool.

At that point, I decided that low-tech is better & as the "sun produces enough energy in one day to power America for a year," or some such like that, Solar it is!

I looked up various versions of a solar food dehydrator & decided to go with one I could build & move, and store inside when not in use... and one that I could make from materials on hand.  The one I ended up building is similar to this
except not nearly as pretty & it sits on a table, not on legs (see above).  Also, no nifty temp gauge. 
If you don't like this design, or don't want to pay that much for one, just go to Google Image Search & type in "how to make a solar food dehydrator" and about a million plans will pop right up, from super-fancy to cardboard box versions. 
There is a pdf. instruction guide that I saved but can't find again "dehydrator guide with photos" and "dehydrator plans" that is really decent.

I did make the door open up vs. dropping down because while I like the shelf idea, it was just too big to be able to reach the front of the dehydrator without some serious gymnastics... and we all know stuff is going to fall at some point.  A hook & eye safety latch will take care of the "crush your head" issue.

$5 Garden plastic for my "black" bits & about $7 on hardware (screws, staples, hinges) for a total of $12 in purchased materials... I may have to calk the cracks for more efficient airflow, which would bring the cost up to around $15.
I used scrap wood on hand, bits left over from when my parents built the addition on the house, scrap lumber that was too short for other things or too knotty for structural projects & an old window that I /think/ came out of the laundry room that they tore down years ago.  The frame is in terrible shape on the outer edges, & the glass is cracked in one place... but for this, it'll work.  I used some old metal shelves that came from ??? for my drying racks & I can put gauze or smaller mesh screen or whatever over them as needed.  Paint was left over from the addition, (which still needs more paint in places).

Since I'm using it to dry dyestuffs, not food, the food safety aspect wasn't a huge issue for me.  I was able to skimp on the food grade screens & I didn't worry about the low VOC plastics or paints.  If I ever do want to dry food, I can always switch out the screens & find different plastic (it's just stapled in).  The paint should be fine after a few weeks anyway, but please do your research if you are going to use this for food; we get enough toxins from commercial food - no point adding them to your home-grown stuff.

The basic principle of the dehydrator is that the air comes in the bottom front opening (screened over), flows up through the airspace & exits the rear top opening (screened over).  The window lets light in to provide the means of heat (sunlight).  The black in the bottom & back wall heats the air as it goes through.  It's very much like a car in a parking lot. 
You can control how much heat & light get in by turning the box toward or away from the sun, and blocking off airflow, or covering some of the black with white cloth, etc. 

While I'm not sure how long some things will take to dry, it does work quite well.  My sage was dry in 2 days & so were the day lilies that I'm collecting for orange dye.  The Queen Ann's Lace seems to be taking a bit longer, which is interesting, if nothing else.

It does have to be taken inside when it's raining as it will wear out quickly if left out in the weather.  You could potentially make a weather-proof cover for it, like the ones they have for gas grills, but personally, I'd rather just bring it in.  In theory, you could use it in a window in the wintertime.

Should be loads of fun, and it's already proving useful.  I don't have to worry so much about things molding or getting rained on if a little sprinkle comes along, or the cats spraying on my dyestuffs (yuck), or a million other problems that come with open-air solar drying.

1 comment:

Gail Kellogg Hope said...

Downside to the solar dehydrator:
if you leave it out overnight the dried stuff reabsorbs some moisture. It's logical.
Have to wait a few hours before I bag things up today.