Home Brew

[v12spirit]

Re: Home Brew

Crushed, calcined, slaked then dried actually. The calcining process is most important for our purposes as it's what makes the stuff react and go hard like cement once water is added to it.

The lime may be the wrong thing in my homebrew weakening it, isn't it? So can I use the available quick lime in my homebrew after soaking it in water for a couple of weeks? and how can I calcine it so long as it should be?

[david s]

Re: Home Brew

The lime may be the wrong thing in my homebrew weakening it, isn't it? So can I use the available quick lime in my homebrew after soaking it in water for a couple of weeks? and how can I calcine it so long as it should be?

Just get hydrated lime. You won't be able to calcine it yourself. To calcine it you would have to mix it with carbon in the correct proportions and heat it to 1000 C.

[v12spirit]

Re: Home Brew

Just get hydrated lime. You won't be able to calcine it yourself. To calcine it you would have to mix it with carbon in the correct proportions and heat it to 1000 C.

Sure. The supplier told me that he had sold me the quick lime by mistake.. I took a sample of the claimed hydrated lime. He asked me what I wanted it for, and told me that it is bought by farmers to smear the legs of trees in order to protect them from insects or something, and to be mixed with some kinds of paints, and was used in the past by adobe owners to underlay their houses with. When I told him that I wanted it for making refractory, he suggested to me to take a sample of gypsum too and try the two mixes. One with the claimed hydrated lime and the other with gypsum. He said: Just give it a try; gypsum gets quite tough when mixed with cement!!
The bag he took the hydrated lime sample from reads: "LIME". Just lime, without any long chemical names. It is a white fine powder contrary to the granules I had.
Will any of these two complement my lime-less homebrew?

[Tscarborough]

Re: Home Brew

I wouldn't use gypsum, but the plain old lime will probably be fine. It is probably single-hydrated lime, i.e. @^*%-house lime, but it will work.

[wotavidone]

Re: Home Brew

Limestone = Calcium carbonate =CaCO3
Limestone is calcined in a lime kiln to make Quicklime = Calcium Oxide = CaO
Quicklime is slaked with water to make Hydrated Lime, builder's lime, slaked lime = Calcium hydroxide = Ca(OH)2

It's usual to use the hydrated lime in mortar, the quicklime could be used but the initial reaction with water can be nasty, and the old timers would slake it for weeks or months.

Agricultural lime, as spread on a farmer's paddock, is crushed limestone or gypsum here in Australia, and would be no use in building ovens. The gypsum would soften every time it got damp (think drywall/plasterboard/sheetrock), and the crushed limestone would not undergo any reactions that would help it harden.

Sodium metasilicate is IUPAC nomenclature for sodium silicate. Sodium silicate (also known as water glass) is used as a binder in some refractories. I think it would need to dry to set. Apparently it's used to bind perlite or vermiculite to make insulating boards.

[v12spirit]

Re: Home Brew

Thanks mates for the helpful inputs. I'm happy that the "claimed" hydrated lime will do the job. I just hope I'm sold the right material.
If I were using my homebrew in making castable refractory (In my case I'm cladding a steel dome oven) is it better to substitute sand with crushed basalt? I found some posts talking about using crushed basalt in castable refractories.. and can I use crushed fire bricks instead or a combination of both? Feels like both have some thermal properties that sand does not have so that I'm tempted to incorporate one or both in my homebrew.

[david s]

Re: Home Brew

You can crush firebrick, I have done quite a lot, but it is really hard work. Do not try crushing insulating firebricks because although they're much easier to crush, You will be introducing air into your mixture.You have to use dense firebricks.You could use crushed basalt but it won't make the mix any denser than using sand.Sand will make the most workable mix and allow you to apply it with the least amount of air in the brew so it would be the best option I should think.

[v12spirit]

Re: Home Brew

You can crush firebrick, I have done quite a lot, but it is really hard work. Do not try crushing insulating firebricks because although they're much easier to crush, You will be introducing air into your mixture.You have to use dense firebricks.You could use crushed basalt but it won't make the mix any denser than using sand.Sand will make the most workable mix and allow you to apply it with the least amount of air in the brew so it would be the best option I should think.

I have three types of sand; two come with pearl-like fine grains one of them is sliver white and the second is reddish, the third is almost like a yellow powder. The first two are more expensive but available as leftovers from my original oven build. Are there any advantages among each over the other?

[david s]

Re: Home Brew

Hard to say from your description, but I use silica sand which tends to have more angular grains which grip better than rounded ones, but any sand should do.

[v12spirit]

Re: Home Brew

I used hydrated lime, Portland cement, clay, and sand in the 1:1:1:3 ratio. The 300 ml brew sample was left 3+ days.. Still crumbly; I could even break it by hands! Does the small volume of the sample weakens the brew that much?

[david s]

Re: Home Brew

Try making a couple of litres of the brew and cover it for a week so it doesn't dry out. Consistency should be "ball up" ie take a handful and make it into a ball. Throw it about a foot into the air, it should not fall apart. Too much or too little water will weaken it.

[Saovicente]

Re: Home Brew

I made a barrel oven with the 3.1.1.1 recipe with the add-on of stainless "melt extract" needles and poly fibers to great success. The oven has gotten stronger from the past six or so months of usage. I last used it on New Years day (temperature was in the low teens) and it performed flawlessly.

[v12spirit]

Re: Home Brew

I made a barrel oven with the 3.1.1.1 recipe with the add-on of stainless "melt extract" needles and poly fibers to great success. The oven has gotten stronger from the past six or so months of usage. I last used it on New Years day (temperature was in the low teens) and it performed flawlessly.

Yes. Exposure to heat will harden the brew. But was your brew initially crumbly? I mean after a week?

[Saovicente]

Re: Home Brew

Yes. Exposure to heat will harden the brew. But was your brew initially crumbly? I mean after a week?

It will strengthen the mix but one must make sure it is a slow, steady process, otherwise there will be a multitude of cracks, especially if the oven if of a singular form. For my mix the compressive strength has been impressive.

To answer your question: No! it did not crumble at all. I have had a few years experience playing with concrete mixes and one of a multitude of factors to good results is heat retention. Simply make your mix (Make sure it is not a slurry mix, nor does it need to be on the dry side) break up your form into four or more pieces (I made 6) Wait a few hours for the form to harden a bit (pending surrounding temperature) cover the lovely beauty with 6 to 9 mil of plastic and a blanket or two (again depending on the surrounding temperature - I made my beauty around the end of march) and let it sit covered for at least 1 to 2 weeks or more. If you need to - put an oil heater under the table to keep the mix hot, especially during the first week. When you touch the mix, it should feel hot to very warm and there should beads of sweat dripping of the plastic.


As an old idiom goes: more than you bargain for hopefully it helps answer your question.

[DavidApp]

Re: Home Brew

Just a thought.
How fresh is your Portland cement? I have been using home brew to cover the outside od my dome. Heat Stop 50 is too expensive to use for that.
I did not notice that it was crumbly and after 10 days it is defiantly very hard.

I will make up a small batch and let you know how it is after 24 hours.
I understand that Portland cement powder will lose something as it ages. Last year I made some Vcrete with an old bag of Portland cement and it a long time to fully set.

David