Blog by Kenneth Lieblich
Welcome to another exciting episode of Kenneth Provides Solutions to Problems That Don’t Exist! In other words, it’s another installment of my Pipe Incident Reports. The idea, in general, is to provide a brief write-up – focusing on a particular pipe-restoration-related issue – rather than an entire restoration story. Today I’m conducting a detailed examination of the issue of pipe mud (aka pipe mortar, pipe plaster, pipe cement, etc.). Heretofore, the standard for pipe mud has simply been cigar ash mixed with a bit of water. This is what Steve uses and, undoubtedly, many, many other pipe men have used it over the years. Here is a link to an article Steve wrote about it and here is a link to an article Fred Hanna wrote about pipe mud, back when Adam was a boy.
The pipe ash mud is useful and simple, but could there be better mixtures? Maybe. The Pipes Magazine forums have a very interesting discussion on the use of ash in pipe mud and I recommend reading it here. What I have written below is absolutely not the first word on pipe mud (and it certainly won’t be the last). I am delving into only a small part of the world of mud.
Before we go any further, let’s answer this question for the uninitiated: what is pipe mud used for? There are several uses, but the most common for me include (1) filling in micro-fissures from heat damage in the walls of a pipe bowl, and (2) lifting the heel of a bowl in order to ensure that it’s more closely in line with the draught hole. For these purposes, we need a material that is simple to make, easy to manipulate, and – once it has dried and set – inert, safe, and hard.
I’ve set myself the challenge of testing several different mixes of pipe mud – in this case, only based on plaster of Paris. I also made a batch with cigar ash, as a control. For the engineers and other scientists reading this article, please know that I have no scientific background and I am not equipped to conduct scientifically accurate tests of compressive (or tensile) strength at my home. However, I’ve done my best to eliminate as many variables in the tests as is reasonable, and I’ve attempted to test the compressive strength of the muds by comparison (and without having access to methods of testing through numbers). Given the disparity in results (and, quite frankly, the frivolity of the project), this proved to be quite sufficient for my needs. The idea for testing mud came to my mind after watching a YouTube video with a particular recipe for what the creator called ‘pipe mortar’. I’ve used it once or twice — it was fine, but nothing special. I’ll discuss its contents in a moment, but as soon as I mentioned it to Steve, he had some issues with it. I also chatted with John Young of NebraskaPeteGeek about it and he also had issues.I first set about making the control mud with cigar ash. I burned a small cigar by Schimmelpenninck until it was fully ashen. I then mixed it with a few drops of water to make a paste and let it set. For reference, I used distilled water in all of the muds – not because I think distilled water is required in any way to make this stuff, but just to eliminate a variable in my production. It’s important to know that ‘hardened’ pipe mud (made with cigar ash) is NOT very hard until the pipe has been smoked several times. It is the oils and tars from the tobacco that actually harden this type of mud.I’m not going to belabour my description of the recipes or the results. The first recipe below comes from the YouTube video I mentioned above. I’m giving all recipes a letter name for ease of reference.
A: cigar ash, drops of water (sorry I don’t have precise amounts for this one)
B: 1.0g of plaster of Paris, 0.5g of salt, 0.6g of activated charcoal, 12 drops of water.Recipe B is the one that Steve and John talked to me about. The creator says that the salt helps in strengthening his ‘mortar’. Steve’s concern is that salt isn’t great for the wood. It can cause tiny fissures, etc. to expand – this is also one of the reasons why Steve and I do not use salt in de-ghosting pipes. Anyway, the amount of salt involved is very small, so I don’t know if this has any effect or not. John, who has a background in chemistry, added that the salt wouldn’t be doing much in the hydrated calcium sulfate reaction. His view was that the salt is unnecessary.
Here are the other recipes:
C: 1.0g of plaster of Paris, 8 drops of water.
D: 1.0g of plaster of Paris, one drop of white glue, 8 drops of water.
E: 1.0g of plaster of Paris, one drop of wood glue, 8 drops of water.
F: 1.0g of plaster of Paris, 0.5g of salt (pulverized), 9 drops of water. In case you’re wondering why I tested both white glue and wood glue, it is because I didn’t realize that they were both polyvinyl acetates. Anyway, in producing the four muds above, I didn’t do a great job of keeping the shape of the samples similar to each other. However, I don’t think this had an overly negative effect on the results at this stage. Definitely the worst of the four in compressive strength was F (similar to B). The middling mixture was C. The best were D and E. I’m giving the edge to E overall, but the difference between the two might just be in my head. They both had good hardness and compressive strength. I have some fine results, but there is an aesthetic problem: the best mud is white! It’s not the end of the world, but it doesn’t look great on the inside of a pipe one has just restored. A new test was in order. I made two new batches of E – but I added activated charcoal to one of them. These recipes look like this:
E: 1.0g of plaster of Paris, one drop of wood glue, 8 drops of water.
G: 1.0g of plaster of Paris, 0.6g of activated charcoal, one drop of wood glue, 9 drops of water.
For this test, I made a much better attempt to have the same shape of mud – a sort of cylinder. The result of the compressive strength test here was definitive: E was notably better. This was no surprise to John. He commented that the charcoal would weaken the structure of the plaster, as it would interfere with (rather than adhere to) the crystalline structure.One thing that I did not test – but probably should have – is mixing pipe ash with plaster of Paris and water. However, given the above results, I expect that it would also be inferior to E.
Here is my (slightly strange) conclusion: although E (perhaps along with D) was hardest and strongest, I am not advocating for YOU to use any particular pipe mud. I have my own thoughts on which mud is best for my work, but my opinion isn’t worth a hill of beans. My goal here is to present my amateurish results, hopefully for your benefit – and that’s it. It is your task now to take the results and do with them as you wish. Special thanks to Steve Laug and John Young for their words of wisdom.
If you make use of these results in your pipe work, please let me know how it goes. I would also be interested to know if you have a different pipe mud recipe you recommend. I hope you enjoyed reading this installment of the Pipe Incident Report – I look forward to writing more. If you are interested in my work, please follow me here on Steve’s website or email me directly at kenneth@knightsofthepipe.com. Thank you very much for reading and, as always, I welcome and encourage your comments.