It’s fun to play in tight wet holes, but use the proper protection!
The Bolting Bible
The Book of Caving
Welcome to our free course as our way of contributing to the bolting community. It's nice to understand what you are clipping and trusting with your life, even if you never plan on installing or removing bolts. Also, if someone is going to spend their time and money to bolt something, I assume, they probably want to do it as good as possible. Hopefully the Bolting Bible gives you the tools you need to do a great job. Get it?
Our courses are A-Z content in blog format, glued together with an over arching blog we call a text book. A blog format is easy to read, easy to update, and easy to translate. Be sure to begin at the TEXTBOOK and at the end of each episode we'll point you to the next.
A huge thanks to RACHEL SAKER for contributing so much information and so much old-bolt porn to this section Also, thank you John Fioroni who operates ExtremeGear.org, and Ethan Reuter for your contributions.
Leave Less Trace
Caves are kept hush-hush for a reason. It's pretty devastating when people don't respect them. It takes a gazillion years for anything to go back to its natural state if people hurt fragile ecosystems, break beautiful features, or just leave a footprint. So please think twice before installing a bolt. Also, consider they can actually help preserve an area by preventing delicate features from being wrapped or preventing grooves from being formed from ropes rubbing the same edge. Think holistically about your impact.
Legalese
Are you allowed to bolt??? Who owns or manages that cave? If it is a new cave discovery, who will be managing that cave and what will they say when they do? Know your area first before installing permanent hardware in it.
If you are replacing bolts, who installed the original bolt? Will they be throwing a fit that you are changing it? Do the cave owners/managers gate keep (get it?) the process or want to at least give input? Know your area first.
Cave Rock
In active cave passages, the rock is exposed to erosion from rain and snow melt just like cliffs and crags. In fossilized passages (a term used mostly in Europe and the Middle East) the cave rock has NOT been exposed to weathering in millenia. Imagine killer flakes glued to the wall by only mud, or 6-ft tall “leaning towers” of choss that collapse when touched, and all the pretty cave cancer that you see pictures of.
Caves can be formed in several ways, but the most common is surface water slowly dissolving limestone. Limestone is mostly dead sea creatures glued together with pressure and time and is generally considered a soft rock. It's not as soft as some sandstone but way softer than some bomber granite. The exposed walls of a cave may be very uniform like poured concrete, or it might just be layered with good rock, then bad rock, then good rock, etc, or it could be a total hellscape with death-flakes peeling off!
Don't Wallow In The Mud
You don't always get easy access to the rock. Walls may also have a layer of mud … if not a heavy layer of mud. It is not rare to see walls with >4 inches deep of heavy mud that must be scraped clean before hitting actual rock. It will take extra effort to clear enough mud off the wall to be able to hear from the hammer strike if the rock below it is bomber. Be mindful to not spatter mud in your eyes because that sucks.
See a real example of navigating mud and installing bolts in a cave
Rock Buffet
Caves often follow faults, joints, or fractures in the bedrock. Therefore, it isn't surprising that the rock creating the cave passage or a pit can be chossy, full of shale, or structurally compromised from geological activity. Even in the same cave or the same wall, it is common to see bands of different quality rock, and some layers may be more sound than others.
Sandstone - Avoid it
Underground sandstone is sketchy because it is totally saturated by moisture. Cave sandstone does not have the baking-hot sun to dry it out or has ever had weathering to exfoliate it's pores (get it?). When selecting a bolt placement, cave sandstone should be approached with caution if not avoided all together.
Chert - Unboltable
Chert, commonly called flint, is the mineral form of silicon dioxide (SiO2), which in English means “evil sharp rocks” and it doesn’t dissolve in water like limestone. It is extremely brittle because it is literally globs of glass that are not structurally sound and it cannot be used for bolt placements. Attempting to drill into it could even break the carbide tip off of the drill bit. Chert can be thick layers, huge blobs, or chunkies in a band of bedrock which should be avoid (if possible) in favor of a more uniform section of limestone.
Calcite - Sketchy
Flowstone (calcite) is formed when limestone is dissolved by water and then redeposited to make all that cool flowy-lookin’ stuff that you imagine when thinking about caves. The umbrella terms for stalactites, stalagmites, bacons, and delicate-shinies are “formations” or if you want to sound super fancy, “speleothems.” The color varies depending on what other minerals are mixed-in with the calcite; it can be white, black, orange, yellow, etc.
Regardless of its shape, the flowstone itself is often porous like a sponge, or heavily layered like book pages, it may be full of voids (pockets), and/or could be completely hollow and can sing like a wind chime when thumped. It can form on practically any surface, too. It may be anchored to a really bomber foundation of bedrock, or it may be a "candy-coating" encrusting mud or gravel or sand, or all of the above. In short: it is often total shit-quality rock and may not even be firmly attached to the cave.
Imagine installing a screw in a phone book instead of a block of wood. The bolt placements in speleothems are sketchy because of how it's layered. If there is a solid wall behind the flowstone coating, and there are no other options, then just make sure the bolt is actually installed in the solid rock behind it. Keep in mind that damaging cave formations can have serious legal repercussions, plus it is just an asshole thing to do!
A bolt is only as good as the rock in which it is placed.
Metal
The vast majority of limestone caves are wet. In the eastern United States, it is very common to see streams underground as well as waterfalls plunging through the cave. Unsurprisingly, these water conditions can vary by season and weather and some caves even flood. Dry caves are often the result of water abandoning that passage (or even the entire cave); this is called a “paleo passage.” That said, most caves are constantly humid (>90% humidity) and the air does not “dry out.” Moisture, be it actively flowing water or humidity in the air, create perfect conditions to corrode non-stainless steel hardware (galvanized, zinc plated) alarmingly fast. These bolts can rust decades faster underground than if that same hardware was aboveground. It is extremely important to use 316l Stainless Steel for the bolt, the washer, the nut and the quicklink! Titanium isn't necessary unless you are near the ocean and the hardware is exposed to salt.
Aluminum is light but oxidizes, especially when mixed with other steel or stainless steel hardware. This should not be left as permanent hardware underground. See how bad these can look in our break tests of flaky and gooey carabiners.
Use 316L Stainless for everything left permanently.
Tools
Check out our tools section of the Bolting Bible for everything you might need but here are some cave specific tips. Everything, like usual, should have a tether in case you drop a tool. Most drills can handle some water but if mud is covering all the vents, the drill could over heat. Your drill may not last very long if you are taking it in caves but you can keep it in a dry bag until you need to pull it out to give it a fighting chance. If your space is confined and you are trying to squeeze glue into the hole, you can add a flexible straw to keep the epoxy gun at a 90 degree angle to the hole. The longer that straw is, the more glue you are wasting.
It's nasty to use a straw to blow out the dust with your lips in a dirty cave, though it is the lightest option. A can of air or air pump is really nice. The cleaner the hole is, the better, but if everything is muddy, remember the priority is to get the rock flower (dust) out from the back of the hole more than it is to get the sides of the hole surgically sterile. Have spare straws and hole brushes since they are relatively light.
Raumer's Action hammer or Petzl's TamTam has a socket in the end to screw on nuts for 8mm bolts. If you are installing permanent 10mm anchors, you'll need a combination wrench as adjustable wrenches might get too dirty to work properly.
Holes
Where do you put the holes and therefore the bolts? If you anchor to natural features or bolt where it is easy to set up for rappel, your rope is likely going to rub the edge as you go down and come back up. IRT means Indestructible Rope Technique and requires a big ass 11mm pit rope that feels as stiff as cable but ironically isn't indestructible and still requires padding. Bigger gear is harder to carry or requires more people to be in a team, both of which can drastically slow you down. There is always a time and place this could make sense to have an anchor where a bomber rope rubs an edge with padding, but there is definitely a better option.
See how a 40 year old Pit Rope held up
Alpine rigging is when you install your bolts so the rope doesn't rub, allowing you to take a much thinner 8-10mm rope. Often, you will need an approach safety line to access the free-hanging rope. You won't always get a clean shot all the way down and may need to have some rebelays or deviations. It's not rocket science to figure out how to keep your rope from rubbing, but it definitely takes caving experience where alpine rigging exists to know how to properly bolt for zero rubbing.
ETHICS
Which one is better? Pull out the boxing gloves and let the forums explode. Bolts are impact, yes, but wrapping speleothems is also impact. Permanently drilling holes is changing the landscape but so are grooves cut into the rock from those "indestructible ropes" rubbing over them. Is a massive amount of webbing wrapping natural features and extending the anchor leaving less trace than two stainless bolts? You decide.
Try to find a balance between doing what everyone else is doing in your area and being a vigilante for a "better system". If no one knows how to use the bolts you've installed, or gets pissed and chops them, was your way better? Culture is one of the things to consider when installing bolts.
HORIZONTAL
Hand lines and lead lines need to be bolted well. You're not really putting force on it... until you are. The anchors can actually can see about 4x your weight if you were to slip and fall onto a horizontal line so take them serious. It's ideal to have 2 bolt anchors, a fully rated rope and for it to be installed chest high for an average person. If you have it at your feet, then fall, doing a factor 2 on a horizontal line... then you might be a highliner and we wouldn't want that.
REDUNDANCY
It's very common to have two bolts for an anchor but what about redirects and rebelays? Redirects with only a 20 degree change of direction is only going to see 1/3 of the force you put on going up or down the rope. Rebelays with a healthy belly in the rope to access it are a different story. Yea, it's "backed up" to the system above it, but if it blows and you drop 10 feet on a very static rope, especially while on tooth devices, you might die. If it would create a swing if the rebelay blew, then the shock load won't be as bad, but then you hit a wall or grind your rope to the core. Have redundancy when the consequences warrant it.
See how you can get more force on an anchor than just your weight
Yesterday's Bolts
There's a good chance you'll see (and use) some gnarly bolts in caves so lets talk about them. When sport caving first became popular, there wasn't specific bolting hardware designed for it, so there is a lot of hardware store anchors. Self-Drives were then designed for caving, where the bolt was the drill bit and could be installed without a power drill. Lithium ion batteries haven't been around forever btw.
These have been around for 50 years and are still sold today. Drop ins or self drives are interchangeably called "Spits" after the first guy who was making them. A little corporate consolidation means that company is not around today. There are two main self-drives made today: Petzl Cheville Autoforeuse 10mm anchors and Raumer's self driving anchor. Self-drives are zinc plated and Raumer makes a 12mm drop in/spit from 316L stainess. Choose your hanger wisely for permanent anchors as mixing metals corrodes some of the components faster.
Quick connect an SDS to 8mm adapter to a hand drill like the Roc Pec. Screw the "drive" part of the bolt onto the adapter and hand drill like normal until the top of the bolt is flush to the rock. Pull it out and place cone in the bottom of it, then pound it back into the hole until it is flush again. The cone spreads out the flanges at the bottom and then you can take the sds adapter off and install your hanger.
Start at 1:53 to see drop ins tested
Drop Ins are the same thing but you need a drill bit. The benefit to these is they can be made in 316L stainless where as self drives cannot because stainless is too soft of a metal to be drilling into rocks. The drop ins have their cones already attached to the bolt, so you aren't dropping or swallowing them.
Pros:
Self drives are intended today for deep exploration where weight matters and you don't want the weight of a drill, or at least a bunch of extra drill batteries.
If you are going to hand drill a hole, self-drives and drop ins are shallow
Cons:
Self drives can't be made out of stainless as the metal is too soft, so they are not a long term solution
They are not as strong since they are so shallow so there is less room for error when installing them. Ideally you have a longer bolt in limestone.
Please don't use these unless you are an expert and know when it's appropriate to do so. If you are going to install them, know these details:
Putting a stainless hanger on a zinc-plated self-drive is dangerous. It causes galvanic corrosion where you can't see it, the part that is holding the hanger to the rock. Don't mix metals.
It must be put in straight and against a flat surface. There is not a lot of bolt to grab that rock so it has to be in all the way.
The back of the hole is what pushes the cone into the bolt so the depth must be perfect. Too shallow and your hanger won't sit flush against the rock. Too deep and the cone will just be sitting in the back, not spreading the bolts flanges out.
If you over tighten the bolt, you can compromise, or even fully strip, the threads.
If your hanger is too thick (today's hangers are thicker than yester-year) or your bolt drilled too deep, then your machine bolt won't have very many threads in the bolt, barely connecting it.
This is the one bolt really requires the hole to be really clean. You can't have rock flower (dust) in the back preventing this from going in all the way.
More often than not, when a spit is replaced, the bolt and hanger is removed and a new bolt hole is created instead of reusing the same hole. If you want to leave less trace, see all the techniques for removing bolts in the Book of Pulling Out. The quick summary is that you have to attach a bolt remover, extract it, drill out the hole deeper and size it up and then install your new bolt. If it is so corroded you can't get the bolt remover on there, you can try core drilling around it or re-tapping the threads so you can screw the adapter on solid.
Today's Bolts
It is becoming more common to see fatter and longer mechanical bolts or even glue ins. A 3/8" or 10mm bolt is super good enough since it's just static rope work, but length is what adds value in a softer rock like limestone. Don't use a short 2 1/4" / 60mm wedge bolt but instead use at least 3.5" / 90mm. All the same concepts apply to installing these as you can read in the "Installing Mechanical Bolts" section of the Bolting Bible.
If you have the time to put glue ins, they can be a great option too. Just be sure to allow double the cure time for wet environments. If gluing overhead, be sure to use thicker glue. Hilti v3 500 will ooze even when 50F/10C but Liquid Roc 500 can almost be too thick to even squeeze it through the mixing nozzle when it's cold. A/C 100 is a good all around glue but it's not as good as epoxy, but super good enough.
Concrete screws are awesome, though not UIAA approved. A 3/8" x 4" (10mm x 100mm) Titen HD is crazy bomber. Read all the nuances in the Concrete Screw section of the Bolting Bible before using them.
Small Stuff
During vertical exploration, lead aid climbing, and general exploration where you don't know where you would want long term anchors, skinny stuff might be temporarily used. This could be a 7.5mm (5/16") Multi-Mont screw or wedge bolt. The screw could be upsized for a permanent anchor or the wedge bolt can be smashed in if you over drill the depth and covered with dirt. Since this is temporary, zinc plated is the best option.
Good Examples
Hangers & Connectors
Cavers are the only group that will leave the same ropes up permanently for a really long time. The perk to playing in the dark: no UV light. Therefore, there are very unique hangers specific to caving but its not uncommon to see very common climbing hangers. Read all about those in the HANGER section of the Bolting Bible. For redundancy on the important issue, we'll say it again: use stainless quicklinks on stainless hangers on stainless bolts. Also, don't install a 5mm or 6mm quicklink to a hanger, use something beefy enough to get a rope in it, at least an 8mm.
Horizontal Hangers - Keeps the carabiner perpendicular to the rock to keep your knot from rubbing. These are not meant to be pulled in tension or it levers on the bolt so don't place these in a ceiling.
Clown Hangers - The rope sits on the bolt and is hugged by the hanger. These are made of aluminum and meant for deep exploration where they will be removed afterwards. See them tested starting at 11:03 of our Dyneema Cave Anchor video. Don't clip a carabiner to them!
Alien hangers - These are a niche 2 hole hanger designed for the Raumer stick up method of aid climbing, though you may see them floating around elsewhere. It only has an 8mm hole so it's not ideal for a permanent anchor,
Amsteel Hangers - An aluminum button acts like a thimble for either a dyneema loop or a soft shackle integrated into it. It is extremely lightweight. They not common so it might confuse people if left permanently and the eye isn't stainless and so it's not intended to be a long term solution underground.
Mini Top by Raumer - A hanger had a baby with a quicklink. No connector needed because it opens! It still leaves plenty of room to connect yourself to the anchor. The problem is they only are made for 8mm bolts so if you wanted 10mm or 12mm bolts you can't use these. Funny they are rated to 25kN when 8mm bolts would rarely hold that much force.
Ring anchors - You can tie your rope directly into any hanger made with round stock. Dupla and Pingos are similar in that you can run a rope in them but keep in mind those only are made in 304 SS and don't come in 316L.
Go Deep In Caving
This Bolting Cave section is not meant to be stand alone material, please go read the rest of the Bolting Bible. And another resource that is super helpful for a niche activity is Derek Bristols channel, specifically his CAVE BOLTING PLAYLIST.