DIY Refractory from Sodium Silicate “Born in fire to survive in fire”

DIY sodium silicate preparation and refractory coatings, fillers and objects that can be made with sodium silicate for small projects are described.

Introduction to DIY refractory

This will not excite all people, but for a tinkerer like me, it does.

“As I expectantly search in my fire to find the virtually invisible object that I have carefully created. I am relieved and excited to find it has survived the ravages of the fire. I am full of awe when I remove the component from the red hot coals with my fire tongs and watch the translucent glowing object slowly return to the ordinary realm to reveal its new colour, feel, hardness and fire-resistant qualities.”

I heard a WA guest potter, on ABC radio, describing such feeling when he opens up his massive, wood-fired in-ground furnace, on his farm, to reveal his giant ceramic works of art. At my small scale I feel a little bit like the wizard Gandalf when he throws Bilbo Baggins magic ring (that was left to Frodo) into the coals to reveal the inscription that reveals that the ring is;

“The One that rules them all,  one ring to find them,
One ring to bring them all and in the darkness bind them.”

John Ronald Reuel Tolkien

“It is most magical when you don’t quite know what to expect, so there is some abstract value in ignorance”

All the little DIY refractory tricks and trinkets on this page have used sodium silicate (water glass) in their preparation. Its precursors, sand and sodium hydroxide, are cheap and abundant. It is a very useful industrial substance and has endless uses for a tinkerer like me (“and probably you, if you have got this far without nodding off”). It is used in thousands of everyday items around us and we are blissfully unaware of it (sodium silicate uses).

I discovered that it could be mixed with materials and metals to make functional DIY refractory coatings, fillings and objects for my inventions and prototype things. Usually, the other components are coated, embedded and bonded and other refractory minerals and oxides can be used to make a new thing that is more resistant to heat.

“Does that sound like gobbledygook? Well, hopefully, it will all come clear if you read on.”

In my best applications, I use concentrated sodium silicate and only use a tiny portion of it in the mix. The same applies to water in the mix.

It is tempting to use more sodium silicate (and water) to make mixing and moulding easy. However, this is a trap for beginners and often less is more!

Note: In my recent searches I have found that the inclusion of a high proportion of fine mineral dust in the silicate mix will, prevent or reduce intumescence. “Intumescence means swelling when rapidly heated……now that’s a good word for Scrabble or the breakfast table if you still have a meal table.”

I find that the smallest practical proportion of sodium silicate (or the maximum amount of refractory mineral) that can fuse the aggregate during firing will give the best product. This means that it will be less prone to excessive softening or ‘glassing’ and intumescence during firing or refractory use in a stove (An example of this can be seen in the photo below, showing sample ‘T13’ ). This is because the sodium content of the silicate acts as a flux to lower the melting point of all that it is mixed with. This fluxing must be limited to make a refractory that is functional at high temperature. See refractory mixing for more details. 

The addition of very high melting point refractory minerals such as aluminium oxide can counterbalance some of this excessive fluxing. It also means that you need to mold with dryish crumbly raw refractory mixes that must be packed into the mold with considerable tamping force with strong resisting force from the mold. This ensures that the component can be removed safely from the mold (if require) without breakage and to get a dense strong product after firing.

“At the risk of sounding like an aged female Homosapien, I will state the bleeding obvious; always make a small test disk of you magic mix before you make the big one.”

DIY sodium silicate

Sodium silicate is very cheap when purchased by the ton but it is not readily available in small quantities in the concentrated form for a tinkerer such as me. Consequently, I make it for myself. It can be made from pure quartzite sand (SiO2), but this too is not easy to obtain in small quantities (please let me know if you can find a cheap supply) and subsequent reaction with sodium hydroxide at high temperature is very hazardous and not advisable or welcome in your kitchen sodium silicate from sand.

A less hazardous (but still hazardous) method is to start with silica gel (cat litter) and react it with a little water and sodium hydroxide powder (drain cleaner). These reagents are both cheap and readily available. The rection is quite simple but protracted. However, any use of sodium hydroxide (in a home or a laboratory) should be approached with great care and adequate protection for; yourself, particularly your eyes, other people, especially little ones sodium silicate from silica gel.

Preparation of concentrated sodium silicate stock solution for DIY refractories

My particular method for making concentrated sodium silicate is a little different from others. My aim is to use as little water as possible so that the finished solution is concentrated (thick and goooopy without leftover silica gel crystals or a crusty insoluble scum. To achieve this I needed to use a little more water and sodium hydroxide. I use:

Water 570g. This should just be clean water and does not need to be distilled water.

Sodium hydroxide  210g. You will need a fresh jar of pure sodium hydroxide (US) Otherwise, caustic soda drain cleaner is available from many supermarkets. However, it must be 100% pure sodium hydroxide or look for another drain cleaner that is. Even so, I use a fresh jar as the contents of ‘stale’ or opened jar will have absorbed carbon dioxide from the air and will have sodium carbonate in it which spoils the end product.

“Don’t worry, this caustic soda still has many good uses for a tinkerer. For example, it can be used as preparation for DIY fruit drying (particularly if food grade as in the US link). Sounds terrible? However, the fruit acids rapidly neutralise the caustic. Trust me as I am a retired chemist who lived to tell the tale.”

Silica gel  300g. The silica gel can be purchased cheaply as a big bag of cat litter crystals that are pure silica gel. “If you don’t have a cat, I’m sure you will find other uses for it as a fellow tinkerer.” If your silica gel has coloured indicator crystals or perfume, this should not matter for making sodium silicate.

The quantities do not have to be exact, I call it bucket chemistry. The good thing is that it will make so much, that you will have a big supply of it for many projects and it keeps indefinitely in a sealed plastic bottle.

Caution 1: Use a safety shield or goggles and rubber gloves as sodium hydroxide is dangerous to the eyes and irritates the skin. (Quality reusable rubber gloves will also be very useful when tinkering with the applications listed below). As a precaution, I like to have handy a big plastic bucket of clean water for emergency washing and also a 2 L ice cream bowl with 1 L of water with ~2 tablespoons of vinegar in it. The weak acetic acid (vinegar) in this will rapidly and harmlessly neutralize any hydroxide that may get on your skin.

Caution 2: The end product, the concentrated sodium silicate liquid, will be quite alkaline and when you are making it or using it you should be ready to quickly wash it off your skin with water and the vinegar solution.

“The slippery feeling on your skin is the alkali reacting with your protective skin oils and turning them into soaps! So wash it off and acidify in vinegar water quickly to stop this reaction. An adequate clean up is when the slipperiness stops.”

Mothy The Elder

For the sodium silicate reaction, I like to use a very large stainless steel pot (much bigger than in the above video), so that it has more metal for cooling and more volume to contain any bubbling boiling and frothing. It can be a cheap stainless steel pot. The chemicals will not harm the pot, and will safely wash off without a trace with cold water. (The reaction might even clean the pot a little as caustic is used as an industrial stainless steel pickling fluid.)

The dissolution of the sodium hydroxide in water produces a lot of heat. The dissolution of the silica gel in the sodium hydroxide at the start also produces a lot of heat, so add it slowly as the heat dissipates. Perversely, to finish the dissolution of the silica gel the whole lot must be heated for some time.

My routine is as follows:

1. Add the water to the pot.
2. Carefully add the sodium hydroxide and mix gently with a long-handled stainless steel spoon to make the crystals dissolve. Slow down the mixing if the solution starts to boil. When the sodium hydroxide has dissolved the solution will be very hot.
3. Next, slowly add some of the silica gel to the hot solution and stir. The crystals will at first float around on top and the heat from the reaction will cause some frothing. When the frothing subsides add more crystals and repeat until all the crystals are added.
4. By this time the heat from the reaction will be exhausted and heat from a stove cooktop will be required to finish the reaction. If some crystals will not dissolve they can be filtered off when the solution is cooled
5. Store in a sealed plastic bottle with an appropriate safety label on it and in a safe place.

Now for the fun bit, the applications of DIY refractories

I mix DIY sodium silicate refractory concentrate with various minerals, metals and metal oxides to make a useful range of DIY refractory components with low to high strength and abrasion resistance.

Refractory; renders,  fillers, adhesives and the ‘traces of magic-refractory-stuff’ that helps it all hold together in hell fire.

The ‘magic-refractory-stuff’ that you might need are listed below:

• baby talcum powder
• red iron oxide
• black iron oxide
• aluminium oxide

The recipes quantities that are expressed in grams are approximate and not critical and teaspoon equivalents (tspn.) are also indicated in brackets. The renders are best applied as multiple thin coats as this avoids ‘runs’ and variably thick layers that do not cure properly.

A. Simple thin silicate render. Recipe; 100g DIY sodium silicate concentrate + 10g baby talcum powder (2 tspn.) + 9g iron oxide (2 tspn.) + 40g water).  This is the basis of all my renders/fillers. It makes a dense, dark (high emissivity) smooth heat resistant coating for stove metal with a higher heat resistance than sodium silicate concentrate (without refractory oxides added). It needs a slow heat curing up to about 50 C to be dry to touch, then further prolonged heating to 100 C to dehydrate most of the water. Then this should be followed by a slow ramped heating to 250 C to remove the last chemically bound water prior to the final high temperature firing to ~500+ C at which stage the coating will be converted into a type of glass or inorganic polymer.

Any cleanup of spilt render or surfaces that need to be clear of render should be cleaned off after the initial 50 C drying as the subsequent curing/firing steps will make clean up progressively more difficult. Clean up can be done with water and cloth or paper and also a pot scrubber at the early stage. Very had abrasives will be needed for clean up otherwise.

Note: Close-fitting surfaces that are contaminated with refractory and are subsequently fired together can bond together so that they will be difficult to separate. This is good if you desire this effect, but bad if the parts need to be separated. Brushes and tools can be simply soaked then washed in water for clean up.

B. Aluminium oxide silicate render. This makes a; thicker, textured and higher heat resistant coating than A-render. It will still be dark with high emissivity but will have a fine hard abrasive sandpaper-like finish when fully cured. Use the same heat curing as described for Render-A.  Recipe; 100g DIY sodium silicate concentrate + 10g baby talcum powder (2 tspn.) + 9g iron oxide (2 tspn.) + 20g aluminium oxide + 40g water).

Alternatively, use render-A and dip the toothbrush into a small amount of aluminium oxide powder to achieve the desired texture/thickness on the surface being rendered. This saves having two or more different renders and allows you to vary the proportion of aluminium oxide for any particular application.

Note: The inclusion of aluminium oxide grits in the render has an additional benefit of acting as a cutting agent when vigorous brushing is used to apply the first base render to a ‘new surface’. It leaves tiny scratches and slowly removes trace contaminants that make the surface hydrophobic.

“Ironically, it is probably my skin oils that have contaminated the metal while working on it and it is the alkaline silicate that will remove it with the aid of scrubbing with grits and an old toothbrush.”

Mothy The Elder

Iron oxide render colour. The same B-render was used on the stoves in the above two photos. The darker colouration of the freshly rendered C-ring stove photo above will changes to a red-brown colour after hours of high-temperature operation (500+C). The colour of the tent stove render has changed to red-brown after much high-temperature operation near the front of the stove cooktop where the gas combustion is largely completed. The rear of the cooktop is less red as it is above the exhaust channel that does not get quite as hot.

For a tent stove, a black colour is best for high emissivity of radiant heat to campers in a small tent. Consequently, it would be tempting to think that black iron oxide (that is less oxidized) would make a better render colour than red iron oxide (that is fully oxidized)

However, I have not put it to the test, but I think both oxides will end up red in the terminal fully oxidized state after surviving hell-fire. If anyone has tried the black iron oxide please let me know how it goes. Anyway, the bottom line is that the red colour is very emissive and much better than bare metal. It also, as a bonus it makes infrared thermometers work more accurately.

Foamed A or B-render. To avoid foaming the render needs slow curing in stages up to about 250 C. In contrast, if the render is slowly dried up to 50 C then on to 100 C and is then followed by rapid heating toward 250 C it will cause the last water of hydration to form steam bubbles and foam in the curing silicate polymer and make the render an expanded foam.

(photo of foamed render)

A and B render as a foam-filler. I largely use the A-render as an expanding filler. It is not strong or abrasion resistant but can be coated with subsequent layers of un-foamed A or B-render to make it stronger and more resistant to abrasion. Deeper cracks or voids in the component will exude tongues of foam, but these can easily be sanded off, and sharp internal corners can be left with a gentle fillet of foam in them ready to receive dense overcoating.

Foamed B-render as a metal cleaner/primer. For sodium silicate renders to bond well to metal surfaces they must be meticulously clean and free of oils (particularly from the tinkers skin), cutting compounds and waxes etc. Even when cleaned the surface should preferably be etched to provide keying for the silicate polymer to bond to.

Simple cleaning is almost impossible to achieve with handmade components. Burning at 500 C, with a lock-in butane torch, is one quick and cheap way of cleaning the surface of small components. However, for larger items, I have found that foamed B-render is particularly useful as a surface priming medium. There can be the combined actions of the;

• Alkaline ‘degreasing’ chemistry of the silicate,
• The abrasive action of the aluminium oxide grits,
• The combination of grits and vigorous brushing with a stiff brush, such as an old toothbrush.

The surface changes from hydrophobic (water repelling) to hydrophilic as the surface is cleaned.

A subsequent firing at high-temperature acts to; clean, and prime the metal surface. Foaming of this render makes this layer easy to remove with clean sandpaper using clean rubber gloves. The surface will be ‘primed’ ready to receive the first permanent render layer. If the dense B or C-render is used for this cleaning/priming it takes a lot of effort to sand off the cleaning coating.

“I know this from experience as I occasionally need to retro weld to a ‘final coated stove’ and it takes a considerable effort with a Dremel tool and grinding cone to clean of a tiny spot of the render to make welding possible. The foam coating, in contrast, vanishes easily like ‘hard meringue’.”

Me

Examples of DIY refractory creations.

Lightweight aluminium/sodium silicate foam matrix.

This is a very interesting application of the A or B renders that can be used to fill large voids, holes or spaces between heat-resistant objects.

Quite accidentally, when I ‘painted’ aluminium foil on both sides with A-render. I folded it and coiled it and stuffed it into a void between two stainless steel tubes. As I tamped it into the void to make it a tight fit, it started to spontaneously heat up, fume, foam, expand and ‘lock-up’.

It makes a lovely tight heat-resistant fill between things such as concentric pipes and can be cured at ~100 C. The silicate ooze and contamination can be easily cleaned up at this stage. Then it can be heated up to ~500+ C for final cure. I often use a propane flame for this because it is so quick.

“I recently used this technique to make some experimental micro oil injectors for my latest hybrid stove. I was in a hurry, so I heated the voluminous aluminium/silicate joint with a propane torch and noticed that flames shot out of the curing matrix. Yes, it is making hydrogen gas during curing. I don’t want to spoil your fun, but be careful of the spontaneous heat if you make this matrix in any quantity and be careful with naked flames.”

Mothy The Elder

The air jet nozzles in the photo below were ‘lost’ in the glowing coals of my kitchen wood heating stove for a day or more of regular use.

“Yes, I forgot that they were in the fire having a short gentle cure at ~300 C. They were sitting on a little refractory stand that was away from the glowing coals, and I just piled more wood in on top of them and they were only recovered when sifting the ash from the fire sometime later (for my compost bin and garden) when I remembered my mistake! Importantly, they survived and were very well cured.”

Me

This material can be cut with a ‘slim’ aluminium oxide cutting wheel and can be sanded with aluminium oxide sandpaper. It does not grind well as the remaining metallic aluminium in the matrix blocks grindstones pores. The cut face of this matrix can be coated with a layer of A or B-render to fill any voids and seal off the metallic aluminium.

Sand ‘stone’

This is a simple and very cheap formulation, but it lacks strength and can be frittered away by abrasion. The weakness of this mix is probably due to carbonate (seashell) contamination and may work much better with pure quartzite sand of non-marine origin.

Aluminium oxide ‘stone’ 

This is a very simple, tough and hard DIY refractory that can take any temperature that can be generated by a tinkerer with wood or charcoal fuel in the house or backyard without the use of pure oxygen. The major component is aluminium oxide ‘sandblasting’ grit that is commonly available from automotive accessory stores such as Super cheap auto.

The resulting refractory; looks, feels and behaves like a traditional aluminium oxide ‘oil stone’. Marks left from knife sharpening can be seen around the edge of the circular disk in the photo below.

“As discussed later this mix can make a tough hot-face render in small stoves where the softer insulated refractory of the core stove material is not adequately strong or abrasion resistant in areas where fuel sticks are fed in and jiggled into place by enthusiastic helpers at a campsite!”

Me

Garnet ‘stone’

This refractory is similar to the aluminium oxide except that it is made from abundant waste garnet grits from the sludge tank that is below a water-jet cutting machine. It is also a very simple, tough and hard DIY refractory that can take any temperature that can be generated with wood fuel in the house or backyard. It is also excellent for knife sharpening.

Perlite, clay and sodium silicate aggregate

This very lightweight refractory that is made with perlite is a very interesting material as it is so light it is like a mineral equivalent of ‘chocolate crackles’ from our unhealthy eating at childhood parties. (Rice bubbles, cocoa, sugar and copha.

“Nearly a perfect construction of an obesity food pyramid, just missing the salt.”

Mothy The Elder

The test disk softened and ‘glassed’ on part of the surface under very hot firing conditions. It survived the ravages of very hot wood fire coals and its density is only 0.3g/cc.

Consequently, with some formulation tweaking and application of a strong ‘hot face render’ to the inside surfaces to stop softening, ‘glassing’ and abrasion, it could have very good refractory/insulating properties for lightweight DIY stoves/heaters. It could be formed in situ in a thin stainless steel or titanium enclosure to provide for its mechanical protection on the outside.

Perlite, sand, high-temperature mortar and sodium silicate.

This refractory mix has a low density and is thermally insulated by the inclusion of perlite in the aggregate. The mix also includes sand and Lanko 156 High Temperature Mortar that is available from Bunnings. Alternatively, in the US, an equivalent would be Dry Mix 211 Refractory Mortar.

Vermiculite clay silicate aggregate

This is another lightweight and thermally insulating refractory mix. It uses vermiculite (instead of perlite) and cat litter clay (I think there are better clays for this purpose), sodium silicate and water in the preparation of the mix.

After firing the surface requires a refractory render coat to make it more resistant to abrasion damage. In the sample (photo below) I drilled a big hole in it after curing at high temperature.

“It was unexpectedly easy to machine with any rotating piece of pipe (no need for teeth). Immediately, in my mind I could imagine that I could make a simple big block of this stuff and machine strategic holes into it to create a small, sophisticated and lightweight rocket mass heater burner body without the need for complex mold building and all the ‘inside-out-thinking’ and issues of allowing for shrinking that that molding entails. This complexity is described in my experimental stick burner post.”

Me

Note: At this stage, it is worth noting that the equivalent lightweight perlite refractory did not machine nicely. I think this difference could be that the vermiculite flakes laminate flat against one another forming large tight ‘platelet-bonds’ that do not break during cutting. In contrast, the perlite grains or balls bond at the ‘kiss contact points’ and resist cutting until they eventually snap off the matrix. The machining swarth from the vermiculite just flowed out easily as a smooth ‘ant-hill’ of powder, whereas the equivalent perlite aggregate had a granular swarth that damaged the cut surface as it exited the hole. In describing the machining as cutting, I think it is more correct to think of it as rubbing and the swarth material is acting as a fine abrasive against the parent material. Because of this, the tools do not need to be particularly hard, sharp or expensive and they can run at slow speeds in a simple drill.

“This means that custom boring tools of various sizes could easily be made in a modest tinkerers workshop.”

Me

Vermiculite, Lanco 156 refractory cement and silicate aggregate.

This mix does not have any clay in the mix.

Vermiculite and silicate only

This is the simplest vermiculite silicate mix and it seems to be quite effective.

Crab-hole-mound ‘stone’

This test refractory mix was born of frustration with clay sources from my farm or local earthworks or pet shop kitty litter clay. None of them made a stable refractory. So I  tried some ‘crab hole mounds’ just for fun. When I mixed it with very little sodium silicate it made a stable refractory that is very strong and as hard as a hard rock. “So maybe those pesky crayfish were part of intelligent design after all.”

You may have guessed by now that I have a propensity for curiosity and a tendency toward natural impatience.  I made a small sample disk of the left-over ‘crab hole refractory mix’ and I impatiently fired it without quite removing the last chemically bound water and it resulted in a ‘slightly puffed’ (intumescenced) test puck of refractory. I imagine that a refractory mix that expands a little, as it finally cures, could be a useful option in many situations, as the most common experience is for refractories to shrink a little as they cure and are fired. “So, impatience is not all bad, especially when it is coupled with curiosity!”

Zirconia fibre felt coating/bonding

This is a delicate featherweight insulating refractory made from thin zirconia fibre felt that can be laminated, bonded and sealed with sodium silicate A-render. I imagine such material could be used for ultralight heat risers in rocket stoves. The outside is finished with layers of render-B, while the inside has an extra experimental render of red clay slip with sodium silicate.

Please see my other use of sodium silicate as a cement mortar accelerant.

Cement and sodium silicate accelerant- to speed the setting time of portland cement

Addendum 1

Post-hole versus crab-hole soil as a DIY refractory matrix.

In the above post, I ‘heap praise’ on a stone-like refractory that can be made with my local crab hole soil as a refractory matrix. I had no sensible reason for why this should be so, especially when other local clays were ineffective.

I was looking for a bulk source of refractory matrix for the construction of a garden cooker/smoker and after a particularly dry summer, there was very little crab activity and very few mounds to harvest.

While doing some real work, I was Post hole Digging on my farm (“I think this is the origin of Agricultural PhDs”). I was systematically collecting the subsoil in a bucket because if you don’t, it “just defies physical laws of conservation of matter” and get mysteriously lost and goes somewhere, and there is not enough left to backfill around the post. With some spare soil left over, I thought; “Would this subsoil be similar to ‘crab-hole-mound’ material?”

I made some test disks with crab-hole and post-hole soils using a ratio of 100g dry ground soil mixed with 30g of sodium silicate. I omitted the addition of an extra 6g of water for these mixes. This meant that the mixing was difficult and slow, but the texture was denser and better for molding. The following test pucks resulted. This started a whole new thread on better refractory mixing.

Both test pucks were strong, hard (equivalent aluminium oxide hardness) no cracking and very heat resistant. The Posthole soil was very easy to collect. I concluded that the two soils were equivalent as a refractory matrix provided that they were ground to a fine powder (and sifted through flywire netting) before mixing.

“I also concluded that crayfish were not adding some magic factor to the mix, as I had suggested (above) as part of their contribution to ‘intelligent design’. In reality, collecting the soil from a suitable depth was probably the critical factor for success, whether done by me with my post hole auger or the crayfish labours.”

An ode to The dreaded virus;

That virus has ruined my planned ocean cruising,
And my shares have copped a real bruising,
With growing BLM awareness and a sense of fairness,
Out of this mess, our thinking may be improving.

Addendum 2

Paper clay as an alternative DIY Refractory

These comments don’t quite fit in this post, because the mix contains no added silicate. However, it is so interesting as an alternative simple ceramic for tinkerers that it should get a special mention. Rudy has read this post and kindly sent me a copy of the text of an interesting article about what I will call ceramic paper clay.

I have made a small test item of paper clay and it was an easy material to work with and it easily survived its birth in fire and at red heat a dunking into a bucket of water.

“When it comes to making functional 3D items from ceramic paper clay it is a lot easier than any of my silicate formulations listed above. Consequently, I highly recommend the post to any keen ceramic tinkerer like me.”

Me

DIY refractory paper clay- “for people who play with fire”

Addendum 3

Use of paper in alternative sodium silicate DIY Refractories

I have made yet another post that looks at using paper to make refractory ceramics with sodium silicate.

Special note:

For me, the making of refractories ”born-in-fire-to-survive-in-fire’ is just a small step in pursuing my passion of making tiny glowing red hot tent stoves that make warmth from a few sticks while winter camping in a tiny tent. If you are interested please see my latest KISS Stove. It is a must-see post if you are fascinated with bush sticks as a source of powerful clean heat for cooking and comfort in a tiny tent. This tiny gas stove makes its own gas from a tiny hand full of truly renewable fuel sticks in a tiny ‘quasi gasifier’ tent stove. It even burns quite happily with damp fuel sticks. “The same principles of hot/clean combustion of sticks can help you ‘fire’ your beloved ceramic creations.”

Tent stove- a tiny backpacking stove

Other related posts

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DIY refractory from soil paper and sodium silicate- “Dirt-cheap & born in fire to survive in fire”

DIY refractory mixing using sodium silicate

DIY Sodium silicate refractory firing- getting the preparation right

Experimental ceramic stick burner

If you happen to be another lover of this wonderful, versatile and abundant element Silicon (Si), you may be interested in my post on silicone rubber for ultralight backpacking gear for all sorts of tinkering tricks.

Or you may like my latest post on a comparison of wonder DIY adhesive made from silicone rubber; Sugru, Kintsugle, Tommy Tape and DIY Oogoo- a comparison

Tim