The Book Of Glue In Bolts

The Book of Glue In Bolts

“The second best way to make a sticky mess.”

The Bolting Bible

This is free resource by HowNOT2 and our way of contributing to the 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. We also believe that if you are going to spend time and money to bolt something, you should do it well.

This book is in a blog format. This page points to all 17 chapters, and the end of each chapter points to the next.

A downloadable PDF is available HERE.

Glue-in Bolts

These bolts have no way of staying in the rock except the chemical bond created by a mixture of chemicals we simply call glue. We'll get to the glue part in the next chapter and installing them in the chapter after that, but for just a basic of metal there are things worth knowing.

Glue-ins can come as a single shaft with a welded eye on top or a continue rod. U-shape (or staples) are a rarely used glue in, requiring 2 holes (one for each leg) which is more impact on an area and rare to see as they are prone to unclipping carabiners. Glue always comes in two parts and is very important to mix it right as most glue in failures is a result of improper mixing. But if mixed right and the hole is dust free, it can offer some of the strongest anchors available.

Mechanical bolts are just pushing on a fraction of the sides of a hole but glue-ins grab 100% of the hole and that is especially important in softer rock or layered rock. The glue gets into the pores of the rock and makes for a bomber anchor compared to a wedge. It also keeps water out of the hole preventing corrosion where you can’t see it. They are much more technical to install and can cost more (if using hilti epoxy) than a mechanical bolt, but they will last a lifetime therefore leaving less of a long term impact.

Do not use glue with mechanical bolts. You don’t get the best of both worlds, you get the worst. The glue will only sit on the outer sleeve and not attach to the actual rod that holds the hanger down. The glue could prevent the anchors from expanding. If the hole is big enough for glue, the wedge won’t wedge. If the hole is the right size for the bolt, there is no room for the glue. The glue can also clog the threads. It’s not like a mechanical bolt is going to fall out of the hole easily if you use glue, but that is not how they are designed. Don’t try to get fancy!

Glue in bolts are a great option for most placements but installation is trickier. They are stronger, last longer and are more convenient to use (not install) since many don’t require hangers. It is thought that the adhesive can help seal the bolt preventing corrosion inside the hole but if you just use 316l stainless (or titanium near the ocean) then that isn't very valid. Longevity and minimal maintenance requirements makes them a great option, especially in soft or layered rock, so let’s go over what you need to know so you can do it like a pro.

Bolt Types

You could just glue anything inside of a hole, but if you are reading this, we assume you are thinking long term and want to do it right. It is NOT recommended to use mechanical bolts with moving parts like we described in the last section. You get the worst of both options. The glue wouldn’t grab the right parts, like sitting on the sleeves and not the actual stud, and the mechanical parts get gummed up by the glue and aren’t free to do what they need to do. And any properly placed mechanical bolt is going to fit the hole so tightly, there wouldn’t be any room for the glue and therefore push it all out. There are bolts specifically designed for glue, so let’s go over those options.

U Shape Bolts / Staples

Also called staple bolts, these are almost never used in highlining and rarely used in climbing, as they require two holes, creating twice the impact, using twice the glue. And consider that the 2 legs rarely share the load so you don’t get 2x the strength. If one leg goes, so do you. AND… when holes are drilled that close together, it could weaken the rock. It also requires more effort to line up the two holes.

If a carabiner gets pulled up and around too much, one of the 2 legs can push up against the gate, potentially opening the carabiner. These are more common on via ferratas where the hardware is fixed. If your rock is very soft, these have more contact area to grab the rock, but if one leg is seeing all the force, then it doesn't seem to make a difference as you can see in our episode below.

Not having a weld, it is one less thing to worry about. To fail, they need to either come out or pull through the metal like a P shape made from a continuous rod. This all happens at forces you will never get in real life so it's irrelevant. Please use

Titan’s U Bolts or (another climbing specific bolts) that are rated, though this episode below is about when we tested an unrated U bolt and is a great demo on HOW they break.

U shaped bolts

We test U shape bolts in this EPISODE

Solid leg glue in bolts

Climbing-specific glue-in bolts generally have an eye designed to sit outside the rock so they don’t need a hanger. These are nice because you can thread it with a static rope eliminating the need for quicklinks. The single rod, or solid leg bolt, has grooves or notches on the shaft for the glue to have something to grab.

This is critical as epoxy glue doesn’t adhere to stainless steel very well (or at all), but stainless is critical for longevity. Solid legs are either welded or forged. Welds aren’t ideal, they are a potential weak point for strength as well as corrosion resistance.

In BoltBusters we have found Fixe’s welded glue ins fail at consistent values but the "Crux Monster" bolts, while all super good enough, are all over the chart. You can see some how some are made in this VIDEO. We don’t recommend you make them by hand as there is a lot that goes into it. It is ideal that gear that many people will trust their life is tested and meets standards.

What about hardware store bolts. We tested forged eye bolts in the EPISODE below and they all broke super good enough. Again, they aren't certified for life support so be cautious when selecting something other people will trust their life to.

“P” shape or Continuous Rod glue in bolts

Another option is a continuous rod that is like a U shape bolt, except it is “P” shaped, so it shares one hole like the everlasting titanium Titan Eterna bolts, the bomber Twisted Leg Bolts, and the popular wave bolt. Some of these bolts require a hammer which is unusual for a glue in. The wave bolt requires a lot of hammering as it fits tight like a compression bolt, and Titan’s Eterna and Bolt-Product’s Twisted leg bolts only need a few taps to fully seat them. The reason for this is so the bolts don’t fall out before the glue hardens when installed by climbers in vertical or overhanging rock. The titanium bolts will last longer than you will because they are significantly more corrosion resistant than 316SS, which is fine in normal conditions.

We are fortunate to have them available as a glue in option, as titanium is still a bit too expensive to manufacture as a mechanical bolt. The glue holds all these bolts well from either the notches in the legs or the bent/twist pattern which snuggles that bolt in the security of all that gooey glue.

Threaded Rod
This is literally a threaded rod glued into a hole. It is also important to use stainless steel (SS) and not cut the end that will be exposed to ensure you have really good threads for you to screw your nuts. Cutting exposed ends also risk leaving iron deposits embedded into your precious SS that can cause corrosion, but that is most likely fine if it is embedded in the bottom of a hole surrounded by glue. Many cut the bottom of their rods at an angle so it helps prevent the risk of twisting the bolt in the cured glue (like if the nut seized on the threads and you were trying to remove it with a lot of pressure). “Why cut it at all?” you ask. So you can buy a 12” rod and cut it in half and have two rods. Threaded rod gives the option of using hangers, removing hangers, or turning hangers for multi-use, such as different highlines that go in different directions.
You can also drill a hole in a hand sized rock, glue a nut in the hole and screw the rock onto the threaded rod to hide bolts in sensitive areas. The risk with threaded rod is that the threads can get damaged, especially if removing hangers is frequent and then you are left with a useless stubby sticking out of the rock. These don’t save you any money as you need to buy a SS nut, washer and hanger to match the metal you are using. These also have been used to glue death flakes to the cliff that you can’t seem to remove. Fully bury the threaded rod and throw a little sand over the exposed glue spot and you have a bomber-ish flake.

Glue In Bolt Buying Guide

Bolt Products

Jim Titt makes great bolts. His website was probably made in the 90s and rarely updated but a lot of the bolting bible came from the information found on his website. They are based out of Germany. Jim is very active in the bolting community contributing extensively on Mountain Project forums.

Solid legs come in 8mm, 10mm, and 12mm. The large 12mm bolts have a thick rod which means better bend radius for ropes. Popular among highliners who use threaded rope for anchors. Size of the bolt is the size of hole required. Comes in 304SS and 316SS. Bolt buster break tests have these welds breaking all over the board but plenty strong enough and I recommend them.

Twisted leg series is a continuous rod twisted to give the glue a shape to hold onto and allow more glue in the crevices. The 6mm rod (12mm or ½” hole) has a very similar feel to a wave bolt and is hard to tell the difference after they are installed. The 8mm rod requires a 16mm or ⅝” hole and is very very hard to break in bolt busters. These also come in 304SS and 316SS. There is also a large eye 8mm version. The USA distributor is Team Tough but has a limited selection listed online. If you contact them, they can source most of the products listed on the main Bolt Products site.

Titan Eterna

Martin Roberts is an expert on Titanium and made the first certified TI climbing specific bolts.

Their ETERNA - TITANIUM GLUE IN ANCHOR BOLT is a continuous rod with no welds and is ideal for corrosive environments such as near the ocean. They are more expensive than stainless naturally but not if you consider these could last 200 years. They did great in our Bolt Buster tests.

He also sells Titanium U bolts and other titanium quicklinks/rings for anchors. Titan is based out of the UK. Martin has been very helpful in this Bolting Bible project.

Wave Bolt

These win the popularity award and are plenty strong enough but I’m not that fond of them. They require a special tool to hammer in and spin as you hammer them so you have to hit them sideways after they are solid in the hole.

The tool isn’t just to keep a carbon steel hammer from leaving iron deposits on your stainless bolt, but it puts the pressure of your smacking on the bottom of the eye which is stronger than hammering the top in. We have bent these installing them during our Bolt Buster tests. The force required to drive them in can cause glue to squirt out leaving air pockets behind. Drill your hole bigger than they recommend to solve some of these issues.

Tip: wallow the hole or use a 14mm drill bit (slightly bigger than ½” or 12.7mm) and they will be easier to get in and you can skip the fancy hammer tool and use a rubber hammer.

I don’t recommend running a rope through them as the bend radius isn’t very large, reducing the strength in your rope. They broke all of our soft shackles before the bolt broke! Some people think the tight fit means they are bomber and the glue is just added strength. We pulled them out with no glue at 1.5kn to 2kn in tension (straight out) in SAMPLES 9 to 11and got 19kn to 27kn in shear in SAMPLES 47, 72 and 73. Pretty impressive but make sure the glue is doing the work since we can get 40kn-ish properly installed like in SAMPLE 31.

Fixe Hardware

Fixe Hardware is the US distributor for the Spanish Company Fixe. While you may see products in their proprietary PLX HCR steel they are currently producing bolts in 316L SS.

There is also talk of a Titanium staple. They have a glue in with no name that we keep calling “bell shaped” with an MBS of 35kn that gave us great results in Bolt Busters (45kn to 63kn in tension). It has a weld but is buried under the glue when notched. Notching these bolts hides the weld which is thought to reduce corrosion as well as preventing a pinch point to trap ropes. The large bend radius is great to thread a rope thru for highline anchors.

One of their more unique bolts is Hely PLX glue in. With a wizard’s cane shape for the glue to grab they are forged instead of welded. These only require a 10mm hole but can also have a rope threaded through them. The eye snapped off of the shaft in Bolt Busters right around the MBS of 28kn. These seem like great bolts but we are not sure if they will continue to make them in 316 SS as PLX gets phased out.

The company had a recall on their PLX products (see metal section) but fixed the issues. They do make great bolts, one of the few retailers that sells Powers sleeve bolts and we love their hangers. They recently updated their website with a clearer message about the proper use of the plated steel products they sell. It is our opinion that plated steel should not be installed outside with the possible exception of lower offs that could see heavy wear and are easy to replace. Plated steel hangers are great for indoor climbing gyms.


These things will break your bank. Their suggested glue cartridges are the worst glue you can use with the most expensive bolts… ironic. They are rated for oddly low numbers but I think they are being very conserative. At least you get 316SS but for these prices of $16 and $27 each, but it should be Duplex Titanium for that price (that’s a metal joke!)

Bat’inox is their big boy at 14mm requiring a 16mm hole.

Collinox is their tiny guy at 10mm requiring a 12mm hole.

Here is a poorly filmed but interesting break test video where the ampule capsule glue failed at 31.7kn. I think we will test these in epoxy for some real fun!

Simpson Threaded Rod

A rod of 316SS, ½” for a 14mm hole ideally (5/8” works too but uses more glue) and cut to 5” - Costs $8.10 for 10” which you can cut in half and the SS nut and washer are $1 each on the same site. So $6 plus a $3.65 hanger from Fixe because SS needs to be compatible.

Don’t buy unrated rods from Home Depot. Buy rated threaded rods that are the correct length, or double length and no longer, so you can keep the factory finished end exposed and put the cut end in the hole with the glue. The cutting wheel will embed particles into the metal that can form rust otherwise.

Vertical Evolution

Based in Italy, Vertical Evolution carries 3 different glue in designs named “arrows”, “glue in arrows” and “glue in rings”. You have to ask them for a price list and wait a couple days for it… not your average website where you can just order something and checkout. They have a lot of via ferrata products and variations of the bolts on this page for different anchor setups. All prices below are from the retail price list they emailed me without VAT or shipping.

“Arrows” are the continuous P shape rods that come in 10mm, 12mm and 14mm sizes. It says stainless but all their other products says 316L but the price sheet I gave specifically says 316L for these. The SS version ranges from €7.90 to €15.20 retail.

“Glue in Arrow” are welded versions of Petzl's solid leg bolts and come in 316SS 8mm, 10mm and 12mm. The 8mm and 10mm are available in a bent version and I’m not sure why? These range from €4.60 - €8.40

“Glue in Ring” is their solid leg P shape bolt but is welded backwards to Bolt-Product’s weld so I’m very curious to test these in Bolt Busters. Comes in 8mm, 10mm, and 12mm and range from €3.60-€6.50

Their open rope glue-ins are for anchors, see the climbing anchor page for more about that.


Raumer is also based in Italy and has a huge inventory of items. They wholesale from this site and so purchasing bolts directly can be a challenge. HowNot2 (that's us) sell their P shaped bolt HERE.

CanyonZone is a European Distributor based in the Netherlands. Raumer has unique glue ins and conforms to EN959:2018 and UNI11578:2015/A standards. All the products below are 316SS.

Their Solid leg P shaped bolts are welded “Backwards” like Vertical Evolution’s bolts and come in 8mm (Antrax), 10mm (Superstar) and 12mm (Masterfix). 8mm shorties are €4.49 and the longest 12mm is €9.35

“Radius” is a welded version of Petzl Bat'inox but is 10mm

They have funny looking staples called “Fork” and come in 10mm in 3 different lengths and are from €3.74 to €4.19 each, but the website says it is specific for caving.

Climbing Technology

Based out of Italy and France, CT carries an 12mm HCR Glue in that is rated for 35kn, goes in a 14mm hole and conforms to EN 959:2007 standards

They also make the same bolt in a 316SS.

They also make a larger size in 304SS that goes in a 16mm hole and is rated for 50kn.

What's Next?

Chapter #10 - The Book of Glue