[shark]

Prompted by a recent conversation on FB that provided great advice on how to reinforce the wobbly jug on Rumble in the Jungle I thought it would be useful to have  a thread that pulled together advice on reinforcing and glueing back broken holds:

The FB conversation was as follows:

Andrew Cherry Climbing at the WCJ Cornice today, noticed the top jug on Rumble in the Jungle is quite wobbly. It wobbles a good 5mm off the main wall, and seemed fairly alarming. Looks like it's already been glued/sika'd, maybe needs reinforcing again? Anyone seen/climbed on it recently, has it always wobbled?

Simon Lee Please glue it

Andrew Cherry if you reckon that's best? i've never glued anything before though, don't want to wreck it!

Keith Sharples Always a difficult decision - glue round it (as in reinforce it) or remove fully and glue back completely. Later defo gives best finish and strongest but requires skill in removal, cleaning and replacing and of course finishing off to make it look non-glued. Never as good (IMO but other may disagree...) to match round it and hope it stays on! The crucial block on Auctioneer came off in my hands so gluing it back on was easy decision/action.

Andrew Cherry Next question then, is there anyone skilled who's nearby/ keen who could give me a hand? Happy to purchase materials etc. I'd be fairly confident reinforcing it with a little guidance/ words of advice, but like you said - removing and glueing back on sounds like it requires a little more skill!

Kristian C BoltFund How big is this block. Is it something you could hold in your lap if it were removed?

Andrew Cherry for sure, it's the size of two fists perhaps.

Kristian C BoltFund Piece of piss then. If you can prize it off then do so to get all the mud out. If not then try to chisel out the old glue and muck and patch it up.

Andrew Cherry Right, I'll have a look when I go back. Recommendations on glue? If there's some other resource where I can read about this then let me know where to look!

Kristian C BoltFund A chemical mortar/resin in a tube is now sold to fit a silicon applicator, the larger tubes need a bigger more expensive applicator. They may come with a mixer nozzle or mix manually in a tub. Screwfix/Toolstation.https://www.screwfix.com/.../easyfix-kem-psc-175.../5650j...
I would not use it for bolts but should suffice for holds.

Keith Sharples Following is my methodology and you may find it helpful. Clean thoroughly as possible (brushes etc)to remove dust and rubbish then inject resin all around and jiggle hold to get resin behind as much as possible. Use an injection system if possible and/or a scrapper to force resin in. In this heat resin will harden quickly so probably mix whilst you're on the rope at the correct location. Monitor carefully whilst setting and hold still during later stages. Just before it totally sets use an old rag (cotton ideal) to smooth over the final exposed surface and remove any excess. Rub rag over adjacent area to get litchen/rock dust on it then rub that into the resin as it finally sets. Use disposable plastic glove from fuel station rather than bare hand and have a couple of carrier bags clipped to harness. Take care with any falling resin to avoid contact with ropes/harnesses etc.
Finally, use a bit of the resin to glue a couple of stones together on ground to ensure resin has mixed properly and then sets...
Leave hold several hours before loading - ie glue at end of session or stay off it on glue-day.
Hope that helps...

Andrew Cherry super helpful thanks! I'm fairly confident I can do this, as it doesn't sound like I'd need to removed the hold (which is the bit I'm not very experienced with). I'm relatively handy and work in a workshop so reckon I can get the mix right etc. Will head out with good intentions tomorrow, and keep an eye on my phone in case anyone has any further advice/ objections

Andrew Cherry Had a go today - after cleaning, got a good amount of glue behind the jug before the whole thing set in the nozzle. Hot weather = very short working time! It could still do with reinforcing at the bottom and edges, intending to go back next Monday and finish the job!

Rupert Davies You've got about a 5 minute hardening time with polyester resin in this heat.

Andrew Cherry Rupert Davies and about 3 minutes before it's almost impossible to get it through the nozzle D: got more pumped than I did on the route!

Rupert Davies Sounds about right. Need to attach the nozzle when you are already in place to glue and take a small plastic bag to take the waste unmixed glue that comes out at the start. But then you know that now...

Rupert Davies Yes. Conversely, if you are doing it in winter it takes about 20 mins to set and you get arm ache holding the hold on until it sets.

David Seb Grieve I was about to mention bring plastic bags, disposable gloves, use an old rope - its okay if you get the glue on your harness, shoes, draws and grigri but not your best RP rope. Also good to have a knife to lever out the metal clip inside since the gun doe not always push it off.

Andrew Cherry David Seb Grieve yup, all of those would have been helpful. Used a nut key in the end. Will be going back better equipped! I've put up a note on the UKC logs too, hopefully it'll be alright for the week.

Mark Rankine If it’s warm I push a small amount of glue through into a plastic bag every few minutes between glueing holds/bolts, to get rid of the stuff starting to harden in the end of the nozzle. Good work

Andrew Cherry This has now been glued! Second attempt went much better, armed with placcy bags and various 'spreaders'. It may not be the neatest job in the world but I'm confident it's not shifting anytime soon. Thanks all for the help, many things learned.

[shark]

Bonjoy also wrote a superb article on repairing holds on grit in : April's Peak Area newsletter

[Bonjoy]

 Lots of good knowledge there.
Here's a good tip I've used for getting around the short nozzle time, tube wastage and cost of spare nozzles. If you don't need to squirt resin into a deep gap, instead of using a nozzle pump the resin into a small sandwich bag. Tie a knot in it and squidge around until the two parts are fully mixed. Then cut a hole in the corner of the bag and squeeze out the resin onto the rock.
Another fairly obvious point - make sure when you put the cap back on a part used tube that any cross contamination between chambers is cleaned off (use a stick or leaf if needed).

[mark20]

Thanks Jon, great article in the newsletter. I missed that first time round. As you know I made the mistake of using an old tube of superglue to stabilise the surface of a hold that didn’t soak it well, and ended up with a plastic-y finish. Fortunately not on anything classic.

 I recently used your tip of putting a drinking my straw on the end of a nozzle, to get glue right into a thin crack/flake - worked brilliantly. Just be aware you waste an entire tube length + the nozzle worth of glue,  so maybe cut the straw in half first

Something I tend to do on routes is have a plastic carrier bag clipped to my harness, and when the glue from the gun is dripping I clip it to my harness and put inside the bag. Instead of just leaving it to swing around and drip everywhere. I noticed one crag in Portland where the lower part of a few routes where covered in glue drip ‘slugs’ - messy.

Good idea to have this in a searchable thread rather than lost on a Facebook/Instagram post, ta Simon

[highrepute]

Bonjoy also wrote a superb article on repairing holds on grit in : April's Peak Area newsletter

Great article Jon.

Also enjoyed the Millstone history piece.

[mark20]

A few pointers for glueing small-ish edges/flakes back on-
If it's not possible to get glue in the back of the hold, carefully lever it off with a nut key, trying to catch any other bits that shatter off. If it breaks into many pieces it may be best/easiest to glue them all together before glueing it back on to the rock.
Use a wire brush to remove dust and dirt from the hold and rock.
Sometimes the greasy glue residue makes using small holds very greasy and hard to hold for quite a while after you've glued it. I've starting putting tape on the useable part of the hold to avoid getting glue on it. Once it's all glued back on, peel it off and you're ready to climb.

[Bonjoy]

To add to Mark's comment on gluing holds back together before they are stuck back on - i've found this is best done using superglue. SG will bond the broken pieces almost instantly and will not distort the shape of the hold so it will fit neatly back on.  It's not as strong a bond as resin though so you do need to use judgement as to structural versus cosmetic significance of the new bond. Likewise when holds are stuck back on with resin you need to think about leverage and loading direction, sometimes a extra blob or bead of resin here or there will hugely increase a holds resistance to ripping off.

[bigironhorse]

Have you guys experimented with araldite? Wasn't the crimp on Tom's roof reattached using it? That seems to have stood the test of time!

[Bonjoy]

I did once. It was smelly, runny, messy and very slow drying. It's also shiny and harder to visually blend in. I think polyester resins are the best bet for hold repair and are cheap and readily available these days.

[bigironhorse]

Cheers. Good thread.

[SamT]

Something I tend to do on routes is have a plastic carrier bag clipped to my harness, and when the glue from the gun is dripping I clip it to my harness and put inside the bag. Instead of just leaving it to swing around and drip everywhere. I noticed one crag in Portland where the lower part of a few routes where covered in glue drip ‘slugs’ - messy.

I made a Glue-gun Holster when I was doing a fair bit of bolting, as per the BP website...

At first glance a strange idea but believe me the stuff gets everywhere and if you let the glue gun dangle on its lanyard you get a tangled sticky mess on the rope or your leg. The glue can drip from the nozzle end and the outside of the nozzle is anyway smeared with glue This is a great idea from my brother which makes life a lot more bearable and costs peanuts,

Get a length of 100mm plastic pipe about 300mm long. Drill a hole for an attatchment loop at one end and fix a carrier bag over the other to catch the drips and smears off the nozzle. As this pipe was corrugated ( it is sold as cable conduit)I used a cord and tanka but tape is just as good. When the bag is covered inside with hard glue just change it.

[Bonjoy]

Just remembered another one. Nozzles often have slots on either side at the end to allow glue out if you are at the back of a drill hole. These are usually unhelpful and lead to mess if you fixing holds. Easily remedied by cutting the end 1cm off the nozzle.

[shark]

Some useful comments on hold repair experiences in Northumberland on this thread copied below:

 

Just on the glue front first off, as that's the most important point raised by Dan and I want to get this straight.

On Nothing Lasts I used Epoxy on 3 footholds and 1 handhold I think. I also put it in the back of the flake I put the gear on. I'd never had to stabilise a route in the Moors and Nothing Lasts was the first route I'd done this on anything. I immediately realised what a mistake I'd made. Dan pointed this out to me after I'd done it. There is no excuse for this. This is the biggest mistake I've ever made as a climber and should have taken greater steps to find out the correct steps. Luckily, the outcome is not horrendous on this. I've top roped numerous people on this line since and none have raised it as a major issue. 

On the Howlerhirst Wall I used Gorilla Glue (isn't this superglue?) on 3 pockets. I could see that the edge of the pockets were starting to wear and wanted to put a stop to this. I regularly attend the NE BMC meetings and superglue is meant to be the way to reinforce sandstone in the county - I really must make it clear though that I've only done this a few times (I think Dan & Steve Blake were meant to be putting something together on this? - would certainly be useful anyway). I did put too much in what I thought was the gear pocket and this has left a smoother finish than natural, which again is not acceptable - I should have made sure I knew what I was doing. What I really didn't want to happen was to fall on the gear and smash the pocket.  I've since learnt from friends in the peak district that this is the result of potentially using old glue and not dabbing it away immediately. I sincerely regret having done this. I think making 2 mistakes of this ilk on two of the best lines in the county is shocking to be honest. I feel pretty bad about it. I don't think Alex has ever talked to me about the use of glue?

*Just re-read that and realised that it sounds like I used epoxy out of choice. It was out of ignorance. I got some to repair a tile at home from a guy in a DIY shop and then assumed it was the same as superglue (which I'd heard of people using on county routes). Ignorance is perhaps not a defence, as I should have read up on it more, but I just assumed glue would either soak in or rub off. As I say, it doesn't effect Nothing Lasts very much and will probably act to preserve it in its current state.

Gorilla Glue (isn't this superglue?)

No it isn't. GG is polyurethane based and is activated by moisture, which causes it to foam up and expand. I've used it a bit for DIY and don't like it as it is so messy. Superglue is cyanoacrylate based, clear, and evaporates off to leave very little residue.

I appreciate the apology.

If you read the last post Steve and I will sort you out with some, Steve does his tests on his garden wall. with normal superglue, it might need dabbed if its been opened or is cold, but with the low viscosity stuff it just sucks straight in so doesn't build up.

Infact i'd go as far as to advise most people on here not to use normal superglue in cold weather as its pretty finnecky once opened and even that can gloop up. Instead i'd advise getting the low viscosity version available from industrial suppliers. https://www.sureloc-direct.co.uk/index.php/cyanoacrylate-industrial-adhesives/ca5-thin-grade-super-glue-1-x-20gm.html
I tried to wreck a bit of house rock with it last week after applying it to an already applied area and it still absorbed in. yeadon is a clear case in yorkshire for preservation, great lines but v soft in a few places. The low viscosity glue darkens the rock more initially but it disappears almost completely after drying. This'll likely vary between grain types so ideally pick a crap bit not on a problem but nearby to test it first.

My personal stance Is to avoid foot hold erosion but not to artificially preserve the difficulty of climbs, for somewhere like sandy it is never going to see a volume of traffic which would even need stabilised, nor would howlerhirst as a rule. Its only really used in areas where the worry is that big foothold scars will develop. EG on northern soul, they were starting to develop so i superglued the first 2 smears and they've stopped, i don't think anyone noticed but its stopped one of the best problems in the uk having its start wrecked. I've snapped holds off lots of hard projects in the county that remain undone, many are still climbable just not necessarily by me, i always just thought of that side as being part of the game. I can also see the argument for not preserving or glueing anything and just accepting our impact, yet when done well its a very invisible job, and when ignored you have examples such as Vienna, the crack, the light bulb, childs play to show what things can become if just left.

The article I wrote featured in a BMC newsletter and can be found here -
In the article I explained the pros and cons of superglue use and my rationale for writing an article. I acknowledge that improper sealing will do more harm than good and argue that full knowledge is better than partial knowledge. I cover the mistakes Franco admits he made. I'd like to think anyone who reads it would think very carefully before doing anything and avoid these and other mistakes.
It's worth a read I think.

To add to the debate on stabilisation.

Along with a couple of others, I have been discretely applying various 'stabilisers' for over 12 years in the county. I along with a number of others from different areas in the UK have shared our experience with the BMC who were going to produce a best practice guide of some sort.  Over the years the scale of the issue in Northumberland,(For example at Bowden.) has been industrial, rather than little bits of damage here and there. The scale of this damage, combined with the low viscosity of superglues, and the issues that can bring, (Such as glazing.) led myself and others here to use commercial masonary stabilisers. These have worked well with apparent good penetration and durability and stopped much of the erosion dead in it's tracks.

Prior to the BMC collaboration I had some dialogue with the group who maintain Southern Sandstone. They advised that a 50% mix of PVA and water worked well, and over the last year I have applied that to good effect. It has the advantage that it can be applied to wet/damp rock.

As Dan alluded to, I have a variety of decomposing blocks in my garden wall that I trial stuff on. The low viscosity superglue that Dan has discovered also has good penetration and when applied properly doesn't seem to affect the surface texture. It's not scientific but I have hammered both the PVA and superglued surfaces on my wall and both have resisted significant blows without cracking or spalling, quite impressive.

The superglue does seem to darken the rock more than the PVA, but personally I'm more concerned about the erosion than any apparent discolouration. Given we plaster the rock with chalk and erode it, worrying about small areas being a bit darker seems to miss the point. The low viscosity of the superglue, and it's penetration does mean it is particularly good for securing small flexing flakes.

In my experience none of the compounds we've used will strengthen edges that are mechanically weak, (the thin lips of some crimps, or sharp edges on some footholds). They can still break, however, the effect on foot scoops and rounded holds sandy holds is pretty remarkable.

I also believe it is worth 'prophylactically' treating areas that are popular, protecting the natural patina before it gets eroded.
This has prevented some Bowden classics  (Y Front for example) from disintegrating.

It's getting late and I'm not going to ramble on any more. Suffice to say that while it's not a dark art, it is easy to make mistakes, as Franco has fessed up to. So I wouldn't endorse everyone starts slapping it on!

Regards,

Steve

[Fiend]

Question from Smally (who I sent a link to the SOTD news thread to, he was impressed by the sensibleness of the debate on UKB, BTW) about stabilisation:

When coating a fragile hold with a stabiliser (masonary sealant, low vis superglue, etc), how are people avoiding the potential issue of the stabiliser sealing the naturally porous surface and thus stopping moisture in the rock escaping through the surface, thus potentially weakening the rock UNDER the sealed area??

Dan and Steve your input from t'County welcomed.

[Will Hunt]

I'm not a geologist, so this isn't exactly gospel, but it does bear similarity to some of the soil science I covered on my degree. A porous rock like sandstone will have a hydraulic conductivity - i.e. the rate at which water can travel through it. The movement of water is driven by a concentration gradient, so water will move from saturated areas into drier areas and the rate at which this happens is in part governed by the hydraulic conductivity (so it will happen slower in less porous rocks).
If the rock is adjacent to dry air, water will evaporate out of the rock and into the air. Because the air potentially has lots of capacity for moisture, and because if the air is moving, the newly moistened air will move away and be replaced by dry air, this creates a strong and persistent concentration gradient which allows moisture to move out of the rock. As rock near the surface loses moisture to the air, this in turn draws water from deeper with the rock (again, because of the concentration gradient).

So the simple answer to your question, in my view, is that even if there was a barrier to moisture leaving the rock, the water would be drawn to the surface (or indeed deeper into the rock, away from the climbing surface) via an adjacent route. You might notice holds taking longer to dry, I suppose, if a larger area had been "sealed", meaning the water was taking a more circuitous route around. This assumes that superglue or whatever creates a complete barrier to water movement - I don't know if this is the case.

[dunnyg]

I heard andy_e loves porosity and permeability so may have some educated guesses to make.

[tomtom]

If its small patches (e.g. stabilising the top of a crimp) I really doubt its an issue as any 'breathing' or minor seeping the rock has to do will go around the sides of an area (if indeed it is sealed enough to make it air/water tight). If its a great bit swathe of the rock then that may be a bit more of an issue. Or not. Maybe,

[SB]

Question from Smally (who I sent a link to the SOTD news thread to, he was impressed by the sensibleness of the debate on UKB, BTW) about stabilisation:

When coating a fragile hold with a stabiliser (masonary sealant, low vis superglue, etc), how are people avoiding the potential issue of the stabiliser sealing the naturally porous surface and thus stopping moisture in the rock escaping through the surface, thus potentially weakening the rock UNDER the sealed area??

Dan and Steve your input from t'County welcomed.

I've sealed some quite large patches over the years and have never encountered any 'Spalling'.  There were some early concerns about 'freeze spalling' (my term for water trapped behind a hold freezing and pushing the treated surface off) but it's never materialised. I suspect the treated areas are such a tiny part of the whole, that moisture has a lot of adjacent surface area to escape through.  The smaller the area treated, the greater that ratio.

[SB]

I have some experience of both Masonry Stabiliser (MS) and Poly Vinyl Alcohol (PVA) which
I have also  recently been using  a low viscosity super glue, which has considerable potential.

My experience is based on the application of stabilising compounds on Northumbrian Sandstone, a rock that varies from being sandy and poorly bonded, to hard and brittle with little mechanical strength to just plain hard! If Northumberland was Granite, or all Basalt, the processes I describe below wouldn’t be required. I’d be surprised if they weren’t relevant to Gritstone.

As a practise, stabilising can stop the ongoing erosion of foot and handholds, and help prevent it in the first place by reinforcing the natural patina (Which in itself varies in its hardness and depth.)

Walking, climbing and bouldering are increasingly popular. It is that popularity which is generating erosion in the hills, but also on the crags and it is extremely noticeable in the Northumbrian honeypots; Bowden looks particularly careworn nowadays and a number of three star classics;  The Crack, Poseidon Adventure,  Lorraine, and others show significant erosion or breakage. It would be churlish not to want people to climb and enjoy the crags, but we need to make sure that individuals and  groups introduced to the crags via indoor climbing  understand what is acceptable practice and what is not. 

The climbing community, the BMC, clubs and importantly indoor walls  should always look to educate and encourage people to be gentle with the rock. Do not climb on damp rock,  Do not over brush, the practice of ragging (Whacking away chalk with a towel seems to have fallen from favour?) works. Always use clean shoes (Modern rubbers are already  very aggressive,  and any  sand on the soles exacerbates and accelerates erosion.)  Do not run laps, repeatedly top rope or shunt, or,  beat  to death a problem or climb on soft rock. Train indoors, and sharpen your skills outdoors and do the climbing in a style that is kind to the rock. It is OK to walk away..

Stabilising deals with a symptom and is not a cure, but combined with good practice could make a huge difference to the sustainability of our sport.

POLY VINYL ACETATE (PVA)

PVAs are typically used as glues (Your kids use it at school) and  as a pre paint primers internally and externally, to bond dusty or incoherent surfaces. They can be purchased at IN 5lt containers at most home improvement stores.

I have used a variety of brands, with no particular manufacturers’ product standing out as more effective; either being more penetrative, hard, or durable.  Those used so far have not discoloured rock, or left a noticeable sheen,  but some bleaching of an adjacent particularly dark lichen has been noted at one location. This is particularly apparent when this slab is wet. However, this discoloration is no worse than the bleaching created by chalk and brushing, or the general passage of climbers over the rock and at least it makes the rock more durable.  In my experience there is little to no discolouration of the rock and what little may occur is a lesser evil to letting the erosion worsen.

PVA  is not toxic to touch, only by ingestion- it is a bit messy but  it’s water soluble  and easy to apply with a spray applicator and brush to stipple it in. Eye protection is a good idea. Follow the application and safety instructions on the containers.  In the absence of any data to the contrary, it is assumed that any contact between these products and 'software' - such as ropes, harnesses and slings, whatever their material renders the kit unsafe. Do not get it on your gear. If you do - then discard it.

Over the last year I have exclusively used Unibond PVA (50%) diluted. I am fortunate that I have a sandstone garden wall with a number of decomposing blocks on which I’ve tested it (and Superglue) on. PVA has been applied extensively on some Northumbrian crags.

If you are contemplating some stabilising, take into account the drying period which varies between several and 24 hours to achieve full hardness. (Though in practice after several hours most products seem to cure)  Saturday morning at a popular crag isn't an ideal time to do this. If there are climbers present let them know to keep off routes/problem.

PVA IS best suited to 'larger' area application such as scooped foot and handholds that are impractical, or too expensive to treat with superglue.

It is also worth considering:
•   Prophylactic treatment of undamaged holds on new (and established) climbs and problems.
•   application to protection slots/cam placements that are eroding.
PVA seems to have good penetration, (obviously the more porous the rock the deeper the penetration) and durability. All stabilisers however seem to eventually 'weather out' or be broken down by sunlight. In our experience a reapplication every couple of years is required.  A photo of a treated hold with a measure alongside can be used as a reference and identify any subsequent erosion. When applying the stabiliser I apply it to the area around the hold, not just to the hold itself, as sloppy footwork and brushing can result in the softer edge being eroded and a creeping increase in the size of the hold, negating the treatment.

 It should be noted that brittle, flaky rock and small crimps are not noticeably strengthened by the application of stabiliser, these fragile edges and flakes will still often break.  However, the residual hold is usually more durable, though a reapplication on the break may be required.  The process is remarkable effective and works really well on large rounded holds or foot scoops that have broken through the patina. The surface texture remains and in most instances you would not notice the treatment.

Thus far we have not notices any ‘spalling’ of treated holds or areas. Theoretically it is possible but the holds treated are all surrounded by porous rock through which I presume internal moisture is escaping.

There is no point in applying PVA  (Or,  indeed Superglue.)  to lichen, moss or surface scrittle. So ensure the area to be treated is clean and if superglue is going to be used, dry.

Some very soft rock can be treated with these materials and with some it’s difficult to determine when to stop brushing.  Be very careful not to ‘sculpt’ the hold. (While  some soft foot scoops could be flattened,  I’ve yet to do this and think restoration vs stabilisation is a separate debate to be had.)  Usually you can quickly tell you’ve reached the most coherent material when there is a uniform  release of grains to the brush or rag.

Also,  ensure as much chalk as possible  is removed from the hold, as any residual chalk may be cemented into the grain, removing texture – not good!  Wetting the hold and brushing it with a fine paintbrush will get most residual chalk into a solution which can be flicked out. Dry the hold with a rag or,  better paper towel, then apply the glue. (An advantage of PVA is that it can be applied to the hold when wet…. )

I usually have the PVA ready mixed in a kitchen spray bottle and spray it onto the hold, stippling it into the grain with a brush. On application it is white, but clears as it dries. (Don’t freak out!)  Most soft rock absorbs it immediately,  I then re-apply until it ‘wets out’ and sits on the surface. I then dab off the excess with a rag.   

As an unscientific test, the blocks I have treated at home I’ve attacked with a hammer. Prior to treatment  you could gouge their surfaces  with a finger.  Two hours later I could not disrupt the surface with a hammer. It is quite impressive.

LOW VISCOSITY  CYANOACRATE  ‘SUPERGLUE’  (LVS)

A little bit about LVS. Until recently I had avoided the use of superglue as it only seemed appropriate to use on very small areas.   However, I was recently passed some LVS which Dan Varian has found online and have been very  impressed by it.

There is an excellent article by Jon Fullwood online on the BMC website about the use of ‘superglue’. This addresses the science, common hazards, application and mistakes that can be made. Please read it.

Undoubtedly all superglues are not equal.  This became apparent to me when studying the Sureloc direct website, where industrial Cyanoacrates are available. These are quite different to the glues purchased in home improvement stores and are available in a range of viscosities, from low viscosity, to thick gels with different glues suited to differing tasks. A ‘de-bonder’ is also available which should remove any excess material.  Or indeed you….. Acetone – (nail varnish remover)  also softens Cyanoacrates and can be used to remove a hardened surface glaze. It has worked to remove a ‘glaze’ in one instance.
 
LVS  (Which Dan Varian found online) has  excellent penetration and produces a similarly tough surface to PVA. (The surface has also resisted hammer strikes.)  Its capillarity gives it an ability to flow into fine cracks. This could be particularly useful in reinforcing  finger  flakes/ edges that are likely to peel away.

With LVS it’s even more important to remove as much chalk as possible, as any left in the grains will be cemented. So wet the hold and lather it up to get the chalk into a solution then flick it out with a brush,  and dry it. You can apply LVS to damp rock, but it will not displace water in saturated rock, so use minimal water and quickly dry the hold. Again keep the rag to hand to wipe away any excess.

As an experiment I have applied LVS to hard ‘good quality’ sandstone in an effort to make it form a skin that could be used to test de-bonder. I haven’t been able to make it form a skin, even having flooded a small depression; it still penetrates and leaves a good texture on the rock.

 It is more expensive than PVA,  but definitely has a place in the toolkit. I wouldn’t be surprised if we find more compounds that also work. Its key attractions are the speed with which it cures and portability. The bottles are small and don’t seem to block – its easy to have one in your bag.

Some random thoughts on grain structure. The vast majority of the rock I’ve worked with (Sandstone) has had a fine and quite even grain structure.   I would think this makes it particularly suitable for stabilising as at a  granular level there isn’t much shearing/leverage on the grains, compared to a coarser grained gritstone where  the grains are more prominent and subject to leverage?

It may be that any prominent grains are sheared off, leaving a more uniform  surface that is resistant to any further erosion. But if the failing grains reveal more of the same then erosion may continue.

(It’s possible that the Glue or PVA will be so strong that it overcomes this and the larger grains don’t shear out.)



Steve Blake

[Fiend]

Informative! Will pass that on.

[mark20]

Does anyone have experience of putting glue in the back of a slot, to stop damp and mud seeping out from the back? It’s a big enough slot so don’t mind sacrificing a bit of the hold, if it will make it drier and cleaner. Thanks

[kc]

It may stop the mud, weather it diverts the seepage is anyone's guess. By making it a cleaning space must surely help.

[Bonjoy]

I've never had 100% success trying this. Could work though if you have enough excess room to make a complete seal.

[SA Chris]

Where is the mud seeping from? Is it dirty water coming down from above? If you try and seal it externally, surely this will just accumulate behind the sealed in area.

[Bonjoy]

You could always leave a weep hole at the side if there is room