I've just completed the proof of concept experiment for preskinning an acrylic form...
It feels alot like drywall. I can pull the skin off if I try, but it feels pretty glued on after 4 days of curing in the mold. I just removed the block today and it released super easily. I sprayed the insides with cooking oil spray and that made using plastic wrap unnecessary.
I think plastic wrap still helps to prevent blow out leakages at the bottom, along with rubber foam weather stripping tape.
After observing a persistent pattern of inconsistency* while using digital kitchen scales to measure foam I have switched to using a double-pan balance scale. Digital scales are based on the concept of "trusting" that it will display a correct reading. However, the simplest test of reliability or precision quickly demonstrates that these devices are not trustworthy. Perhaps some are. Even in the best scenario, you are left trusting the digital scale every time.
A classic balance scale requires no trust factor. Any child can readily observe the reliability, accuracy, and precision of a balance scale with each measurement in real time. The ramifications of attempting to make aircrete with incorrect and inconsistent foam density information are significant enough to make the idea of "trusting" digital scales seem ridiculous.
DSC_0053 (1) cropped and sharped.jpg
In this image, I have a cup containing 135 grams of foam. The clear plastic container on the right pad was filled with the precise amount of water to tare out the cup. The other weights used (100g, 20g, 10g, and 5g) are offsetting the weight of the foam only. If the sample contained 136 grams of foam, I would push the slide weight over to the one position.
I made the cup tare weight and the 5g weight myself easily enough. This balance scale is very intuitive and simple to use. The real reward is knowing that my reading is accurate every time.
*Different digital scales gave different readings of the same samples, varying by as much as 20%. At times I watched the tare shift by 10 to 15% from second to second.
The typical aircrete job site has various risk factors for electrocution that should be considered.
High-amp hand-held power tools (such as a drill or paddle mixer)
These three factors are present on nearly every aircrete job site. Combined, they present a well documented serious risk for fatal electrocution. These risk factors can be moderated by using tested ground fault circuit interruptors (GFCI) and with proper use of well maintained cords of appropriate gauge and materials.
The following is taken from National Institute for Occupational Safety and Health
(NIOSH) PUBLICATION No. 98-131 WORKER DEATHS BY ELECTROCUTION
Estimated Effects of 60 Hz AC Currents
1 mA Barely perceptible
16 mA Maximum current an average man can grasp and “let go”
20 mA Paralysis of respiratory muscles
100 mA Ventricular fibrillation threshold
2 Amps Cardiac standstill and internal organ damage
15/20 Amps Common fuse or breaker opens circuit*
* Contact with 20 milliamps of current can be fatal. As a frame of reference, a common household circuit breaker may be rated at 15, 20, or 30 amps.
The presence of moisture from environmental conditions such as standing water, wet clothing, high humidity, or perspiration increases the possibility of a low-voltage electrocution. The level of current passing through the human body is directly related to the resistance of its path through the body. Under dry conditions, the resistance offered by the human body may be as high as 100,000 Ohms. Wet or broken skin may drop the body’s resistance to 1,000 Ohms. The following illustrations of Ohm’s law demonstrates how moisture affects low-voltage electrocutions. Under dry conditions, Current=Volts/Ohms = 120/100,000 = 1 mA, a barely perceptible level of current. Under wet conditions, Current=Volts/Ohms = 120/1,000 = 120 mA, sufficient current to cause ventricular fibrillation. Wet conditions are common during low-voltage electrocutions.
Due to the dynamic, rugged nature of construction work, normal use of electrical equipment at your site causes wear and tear that results in insulation breaks, short-circuits, and exposed wires. [Flexible Cords and Power Tools] If there is no ground-fault protection, these can cause a ground-fault that sends current through the worker's body, resulting in electrical burns, explosions, fire, or death.
How Do I Avoid Hazards?
• Use ground-fault circuit interrupters (GFCI)s on all 120-volt, single-phase, 15- and 20-ampere receptacles, or have an assured equipment grounding conductor program (AEGCP).
• Follow manufacturers' recommended testing procedure to insure GFCI is working correctly.
• Use double-insulated tools and equipment, distinctively marked.
• Use tools and equipment according to the instructions included in their listing, labeling or certification.
• Visually inspect all electrical equipment before use. Remove from service any equipment with frayed cords, missing ground prongs, cracked tool casings, etc. Apply a warning tag to any defective tool and do not use it until the problem has been corrected.
The normal wear and tear on extension and flexible cords at your site can loosen or expose wires, creating hazardous conditions. [Flexible Cords] Cords that are not 3-wire type, not designed for hard-usage, or that have been modified, increase your risk of contacting electrical current.
How Do I Avoid Hazards?
• Use factory-assembled cord sets.
• Use only extension cords that are 3-wire type.
• Use only extension cords that are marked with a designation code for hard or extra-hard usage.
• Use only cords, connection devices, and fittings that are equipped with strain relief.
• Remove cords from receptacles by pulling on the plugs, not the cords.
• Continually audit cords on-site. Any cords found not to be marked for hard or extra-hard use, or which have been modified, must be taken out of service immediately.
If electrical equipment is used in ways for which it is not designed, you can no longer depend on safety features built in by the manufacturer. This may damage your equipment and cause employee injuries. [Power Tools]
Common Examples of Misused Equipment
• Using multi-receptacle boxes designed to be mounted by fitting them with a power cord and placing them on the floor.
• Fabricating extension cords with ROMEX® wire.
• Using equipment outdoors that is labeled for use only in dry, indoor locations.
• Attaching ungrounded, two-prong adapter plugs to three-prong cords and tools.
• Using circuit breakers or fuses with the wrong rating for over-current protection, e.g. using a 30-amp breaker in a system with 15- or 20-amp receptacles. Protection is lost because it will not trip when the system's load has been exceeded.
• Using modified cords or tools, e.g., removing ground prongs, face plates, insulation, etc.
• Using cords or tools with worn insulation or exposed wires.
If the power supply to the electrical equipment at your site is not grounded or the path has been broken, fault current may travel through a worker's body, causing electrical burns or death. [Flexible Cords and Power Tools]. Even when the power system is properly grounded, electrical equipment can instantly change from safe to hazardous because of extreme conditions and rough treatment.
How Do I Avoid Hazards?
• Ground all power supply systems, electrical circuits, and electrical equipment.
• Frequently inspect electrical systems to insure that the path to ground is continuous.
• Visually inspect all electrical equipment before use. Take any defective equipment out of service.
• Do not remove ground prongs from cord- and plug-connected equipment or extension cords.
• Use double-insulated tools and equipment, distinctively marked.
I'm trying to select an air compressor to buy for home use. This is my first time buying a compressor, as I've never used anything other than my dad's old belt driven monster with something like a 400 gallon tank.
While we haven't pumped vertically, we've successfully pumped horizontally by making our aircrete mixing container air-tight, then pressurizing the top with an air compressor so that the mix would flow through a hose attached at the bottom. Doing so seemed to have little effect on the foam, which set fine under the concrete slab we filled beneath.
I hope to get some foam technology advice here as to how to fine tune the foam density recipe.
I used two 5 gallon buckets, one stacked inside the other. The whole kit fits inside the top bucket for storage and transporting.
I had to change the inside of the whole house filter with a 1" piece of pvc pipe cut to the length of a filter and I drilled a whole bunch of little holes at the bottom of the pipe to direct the foam up to the outlet.
I stuffed it full of stainless steel wool around the pipe and a wad of it up in the filter housing top, where I drilled and tapped a fitting for the air inlet. There was already a water pressure relief valve there.
The pump is a 12 volt sealess marine coolant pump made by Johnson.
I was getting consistent ~70g/L foam at about 20 psi air pressure , consistent ~50g/L at 25 psi, and consistent ~110g/L at about 15 psi. I could not get it right at 90g/L.
This is just cheapo Kirkland brand Costco dish soap for testing purposes only. I mixed it at 2 cups per 5 Gallons H2O.
I consider this experiment a total success. Now my question for you experienced with foam generating, is what effect does using less soap in the water have? If my foam is too light at 25 psi, will using less soap in the water make it heavier??
That was with 50psi air pressure. I think I need to stuff more ss pads into it https://photos.app.goo.gl/zHxgcADfLUCQXJTS8
The pump is a Johnson 28watt 12volt sealess 22.5L/min
It fits perfectly at the bottom when you put the 2 buckets together.
Domegaia provides a great bit of information and inspirational ideas for building a cost effective, low maintenance, practically indestructible by nature haven/home and I thank them for that.
Comparatively, yes, the ecological impact of an aircrete home is much less than the traditional North American home with all the toxic materials used. (eg: asphalt shingles, vinyl siding, other plastics, insulation, paints, stains, other manufactured materials, etc...) Domegaia has provided a better alternative but, not a true environmentally friendly option either, as they seem to tout. Take your time and understand where "cement powder" comes from. Please. Before you choose this option. With that said, I am a true fan of the cost, the time, labour, low maintenance, and the benefits to the environment that this option does offer.
Personally, I would be much happier if Domegaia could/would have provide(d) some other ideas rather than commercially sourced cement powder, an organic fabric option rather the polyester fabric, and a more organic option than a latex bonding agent. I would then call this a truly eco-friendly option. Sorry for the strange rant. lol.
Having been inspired by Domegaia, I went ahead and purchased a number of their products offered in their online store. I now have the Little Dragon, the mixer and foam injector, (none of which I've had the use yet) and I also purchased their digital student hand book.
The Little Dragon DIY kit came as advertised but does not come with pvc glue and for the price they charge, it should be included, in my opinion. The paper instructions are fairly different from the video assembly tutorial. I used both. It looks great when finished and I expect will run without a hitch. The convenience of the kit was great but, I probably should have sourced the parts myself and I have saved a good amount of money. More time and effort though. It would be a trade off.
The other cost prohibitive factors were the shipping and customs fees as I'm in eastern Canada. The tax and duty from customs for the two separate shipments required for the mixer and the Little Dragon cost me over $150cad plus the shipping costs. With the taxes and duty I should never ever have bought their mixer. I could have found one of equal or better quality in my local hardware store. The mixing wand appears to be great quality and strength (although hand built likely rather than machined precision) compared to other of the same size I have seen elsewhere.
The student handbook, is way over priced and most of the information provided can be found, for free, on Domegaia's own website, forums, and videos. The floor plans that come with it are great for inspiration but otherwise nearly useless if you're not building that exact home. I meant to buy the master class instead and forgot at the time of purchase as I was do excited to start this journey. Lesson learned. Don't shop online when you're not focused.
I look forward to starting my adventure with aircrete. I feel you are overcharging for your digital content and the other concerns mentioned above but, I do thank you Domegaia for what you have provided. Keep up the work. A cold weather Canadian dome workshop would be greatly appreciated. I have access to a beautiful farm where we intend to build in rural New Brunswick that would fit right in with what appear to be the companies morals and beliefs. This would be an exceptionally ideal location for your first Canadian workshop and I could use the help building my dome. Wink, wink.
Thank you and good afternoon, good evening, good night, and good morning to you all.
HELP PLEASE ! Hi I purchased a DIY little dragon kit a week ago and it was missing the Front Cover and one CLAMP for the WAND . I emailed 4 to 5 days ago but I got no email back. ANY way I managed to make a cover and assembled it to find out that soon as I put the air pressure on the pump LOSES its prime. I checked for leaks and I can't find any . Wondering if the pump is defective.