However, with a few simple supplies and some elbow grease, it's possible to transform something, that you wouldn't dream of putting near your mouth, into a handsome pipe that should give you many years of faithful service and comfort.
Please note: Whilst I've restored over 20 pipes, I have only been doing this for less than a year! I am NOT an expert but I have found that the following techniques work for me...if you have an expensive "artisan" pipe or a treasured heirloom, please use caution! If in doubt, either take it to your local pipe shop or practice on cheap ones first!
The two main symptoms of old age (in pipes anyway) are oxidation and "cake". The first is when the stem goes that horrible sulphurous yellowy-brown colour and is a direct result of Vulcanite stems being exposed to UV light and heat. The second is the build up of carbon (from the natural sugars in burning tobacco) inside the bowl. If a pipe has been reamed regularly, the cake shouldn't be too thick but I've seen some bowls that you couldn't even fit a tamper or your little finger in!
The first thing to do is to CAREFULLY separate the stem and bowl. If it feels completely stuck, I like to drip a little 99% alcohol around the join and leave it to sit for a while. Alternatively, put the pipe in a plastic bag and stick it in the freezer (the bag prevents a "domestic"!) for a while. Being different materials, the bowl and stem will will contract at different rates.
As well as oxidation, an old stem is likely to be full of old tar and ash. To help remove this, I like to soak my stems in alcohol first (I either lay them flat in a shallow, square Tupperware dish, or stand them in a tall, narrow glass jar). Please note, any logos or inserts on the stem may be damaged by this process, so if you want to keep them try a different technique! For scrubbing out the interior of the stem (and the mortise) you can use bristle pipe cleaners. However, as I clean a few pipes, I got myself a set of airbrush cleaning brushes. They're reusable and the variety of sizes makes them more versatile.
To remove the oxidation itself, I soak the stems overnight in a bleach solution. Any painted logos can be protected by covering them with a dab of Vaseline. It's best if the stems are completely submerged, so that the finish is even. I'll usually turn them occasionally as well. After the bleach soak, rinse the pipe well in running water (I do it at the bathroom sink). At this point, the stem should be a matte black with a rough surface texture.
You can use any fine abrasive at this point...500grit wet and dry sandpaper is good, especially if you follow it with finer grades. However, I've found that Bar Keepers Friend (applied with a soft, fine weave, cotton cloth) works really well! I found it in my local ASDA. Wet the stem, then dip a damp cloth in some of the BKF and rub gently. Particular care should be taken when using any abrasive, as it's possible to remove too much material if you're not careful and round the button. Do not use any on the tenon as it's very easy to end up with a loose fitting stem! Because the BKF is a very fine abrasive, you're removing very little material so it takes longer but the results are worth it (imho). To finish off and get that "as new" shine, apply some Vaseline or lip balm to the stem and polish with a soft cloth (an old, cotton, t shirt is ideal). I've heard of people using olive oil and I've used Renaissance Wax in the past but the Vaseline has less after-taste and seems to give a long-lasting shine that resists oxidation recurring.
There are alternative methods, using a buffer and jewellers' rouge, but this is the technique I've found that works without power tools. I've also heard good reports about the "Stem Restore Kit" from Walker Briar works.
Rejuvenating the bowl:
You might have heard of the "salt and alcohol" treatment, for cleaning a bowl...it's particularly good at exorcising stubborn ghosts from tobacco you've smoked in the past. The general consensus (on the forums where the majority are American) is to use Kosher salt and Everclear...the former contains no iodine (or other additives) and the latter is 70% abv Grain Alcohol (drinkable but approaching "moonshine"). A UK alternative can be sourced using coarse Saxa rock salt and high proof spirits (the selection is limited to a few cask strength whiskies and white rums). To my mind this seems a criminal waste of "good" alcohol, so for "deep cleaning" my bowls, I use Isopropyl Alcohol. At 99% this is not suitable for consumption, so some extra steps need to be taken. Additionally, as an alternative to salt, I've found that a cotton wool ball makes less mess and is easier to remove...plus there's no risk of you ending up with your pipe soaking in brine!
Start by making sure that your pipe is empty and clean...I use a scrunched up paper towel to remove any left-over ash from the bowl. If you have a bent pipe you can leave the stem attached, otherwise remove the stem and insert a pipe cleaner to block the draught hole. I've tried various methods to keep a pipe upright during the cleaning process but found the simplest solution is to use an old egg carton.
Fill the bowl with salt or a cotton wool ball (or two), almost up to the rim...don't overfill or you risk ruining the exterior stain. Then, slowly and carefully, fill the bowl with your alcohol. I use a syringe as it makes it easier to control the flow. You want the salt/cotton wool to be saturated but not running over. Stand the bowl upright, preferably with the shank slightly raised (this reduces the risk of any leaks/drips). Leave the pipe for at least 24 hours in a well ventilated place...I use the kitchen windowsill...to allow the alcohol to evaporate. If you are using salt, you'll see a hard brown crust forming on the top. With cotton wool, the colour will also change to a dark brown (shade varies depending on how dirty the pipe was to start with). 70% alcohol can take up to 48 hours to evaporate.
After the salt or cotton wool has dried, carefully remove it (and the pipe cleaner from the draught hole)...if you're using salt, there might still be a saturated clump at the bottom of the bowl so watch out for any drips. If I'm happy with the "exorcism" at this point, I'll leave the bowl standing empty for another 24 hours...otherwise, I'll repeat the process. At this point, when I'm using the Isopropyl Alcohol, I'll give the interior a wipe out with some kitchen paper dipped in 40% abv spirits (supermarket "own label" Whisky, Brandy, Rum, or Vodka are all suitable), before leaving it to air dry again. I'm not a toxicologist but I'm happy that the extra swab and extended drying period are sufficient to remove any potentially harmful leftovers from the Isopropyl. If you use salt, give the bowl a good shake and a wipe out, with a dry paper towel and some pipe cleaners, to make sure all the grains are removed.
If the cake is uneven, or too thick for your taste, you can ream the pipe at this stage. When I started, I used a "Buttner Reamer", now I use a "Senior Reamer" as I find it's easier to control and fits my "U" shaped bowls better. However, if you have pipes with a "V" shaped chamber, the Buttner is generally a better fit. It is also possible to ream a pipe using fine sandpaper wrapped around a suitable diameter dowel or pencil. Tip out any loose carbon from the bowl and give it another dry wipe.
Tidying a "charred" rim:
If the rim looks charred, try cleaning it first before resorting to more drastic measures...most of the surface blackening will usually just be tar.
Moisten a cloth with saliva (it sounds rank but your mum was right, when she used to clean your face with a hanky and spit, it's a very efficient solvent) and start to rub the rim. You should see a lot of the black deposits lifting. The more stubborn rough areas can be scraped with a fingernail. Repeat as required. You can shorten the process using a cloth, or cotton bud, dipped in alcohol (40% abv should be sufficient strength) but make sure it's not soaked, otherwise you risk damaging the pipe's finish if it drips.
I've only had a couple of estate pipes with very badly damaged rims; one was beyond salvation (with my limited tools) and the other had some deep cracks and burnt areas from misuse, this needed to be sanded down past the damaged area. For this I used wet and dry sandpaper and a sheet of glass (to give a level surface). I started with 500 Grit paper and moved up through the grades to 2500 grit. Use a circular motion to keep the rim level as you remove material. Check frequently that you're staying level and not going too far. This process will change the shape of the bowl so it might be a bit extreme unless you have a pipe that's a particular favourite you want to resurrect!
Before reassembling your pipe, you can give the bowl and stem a quick clean with more pipe cleaners to remove any stray residue that might remain...there are "pipe sweeteners" available but I prefer to just use one cleaner dipped in Whisky/Brandy, then a couple of dry ones. Your pipe is now ready to smoke!
My apologies for the lengthy post. I was going to post this as a separate "page" but thought keeping it as a post, that could be commented on, would be more useful.