Why Turn Punky and Soft Wood?

Alan Wasserman looks at using imperfect wood, starting with the implications and things to consider when using soft ‘punky’ wood.

Alan Wasserman looks at using imperfect wood, starting with the implications and things to consider when using soft ‘punky’ wood

Why write an article on using imperfect wood for your woodturning project? Imperfections in wood can include rot, spalting, discolouration, bark inclusions, worm holes, voids, cracks, fissures, etc. Each has implications when they are present in the wood. Some might say that if the wood has imperfections it should be thrown on the fire pile – after all, wood grows on trees! 

Timber

Quality wood can be located and bought from many sources. Perfect timber costs money – depending on the species and figuring, a lot of money – but it can be what is required. What about wood that isn’t quite perfect – like getting our hands on a piece of driftwood or being offered or coming across a felled tree or sections from a tree surgeon? What about natural edge blanks or burrs?

These are highly likely to have faults or imperfections. Also, we might find – like I did when I started a 355mm bowl that had no visible signs of having defects or imperfections – seriously soft and partially rotten timber become evident while turning the outside to a rough shape. Other examples one might come across where there is a desire to turn work that is less than perfect are:

  • A family heirloom piece of furniture that is unrepairable but can be re-purposed into a woodturning project that will pass down the family and last many lifetimes
  • An exotic and valuable piece of wood that ‘needs to be saved’
  • You may have worked long and hard to create a satisfying form and then discovered an imperfection that needs to be corrected or managed to save the extended time you invested
  • A piece of wood that costs a lot of money and you don’t want to end up with nothing
  • A down section of tree that looks as though it will yield interesting timber.

While all of the above – and no doubt people will have many more reasons to want to turn a piece of less than perfect wood – are valid reasons, there are of course implications and considerations to be borne in mind when working with such wood.

Considerations

Truthfully, it comes down to you being brutally honest with yourself about making an assessment on the nature of the fault(s) in the wood, analyse the risks of what can go wrong and what can be done to remove or minimise those risks to an acceptable level. You might find that the risks are too great or beyond your ability to effectively manage and minimise them. There is no point in unnecessarily placing yourself in harm’s way.

Remember, even if you can analyse the risks and have the skill level, always ask if it is worth the effort or risk. Conversely, you might find that with systematic planning, sensible analysis, appropriate precautions and working methods, you can work with or salvage something from the piece of wood you have. This exercise is really quite rewarding.

Causes

Punky or soft wood is often found in timber that has been down a long while and is at various stages of the spalting process or starting to rot due to water damage, infection and suchlike. Many standing trees exhibit areas of damage that may well at some stage start to rot.

But we have all, no doubt, come across wood that is soft and we know will  be hard to cut – often prone to tearout or pluck out – and even if it can be cut reasonably well, it doesn’t sand well as it will sand quicker than the surrounding harder areas, leaving an uneven surface. The amount of soft or punky areas encountered will vary considerably from piece to piece. It is worth noting that some species of wood are naturally soft even when no rot is encountered, so the following comments hold true even when working those types of timber.

Control location of holes to the centre of the piece and placing the dip of bark saddle pointing down at the hole
Control location of pith-parallel
A punky piece before shot
Soft punky timber on a burr

Safety first

The truth of the matter is that you will not remain a woodturner for long if you are the victim of an exploded imperfect 50lb piece of wood, turning at speed. That applies to solid sound wood or sections of compromised timber. Never undertake any turning without the proper protective gear and procedure;
at best you will have permanent injury and at worst…

So, how to protect yourself when turning a ‘challenged’ lump of wood? The following applies to any size and condition of work being turned.

  • Make an honest opinion of the quality of the wood being looked at and assess whether it is safe to work and if you have concerns but still want to turn it. Can the risks be managed well and appropriately to minimise the risk of something going wrong?
  • Make sure you have a minimum of a sturdy full properly high-impact rated face shield, appropriate personal and at source dust extraction
  • Never stand in the line of fire – potential exit path of your work – until your piece has been secured in your final choice of holding
  • Never tackle work that is beyond your ability
  • Make sure your work is properly secured on the lathe before switching on the lathe. The method of fastening needs to adapt to the type of imperfection (face plate vs glue block vs four jaw chucks, etc.)
  • Some lathes come with a heavy duty mesh over the screen to use when turning. If your lathe has them, use them
  • The tailstock is your friend.  Use the tailstock for additional security whenever feasible and not a hinder to accessing your work.  Whether you are using a faceplate, glue block, chuck or other devises for final mounting, the tailstock should be used to add extra hold  of your work to the headstock
  • Ensure that you have selected the right speed on the lathe commensurate with the size and condition of the work
  • Never assume anything is totally secure. Always stop the lathe regularly and check to see what is happening. Check for hold and deterioration on condition of the timber
  • Always wear an appropriate respirator suitable to deal with dust and potentially toxic hardening/finishing products.
Always stand out of the line of fire – the potential exit point – of work while you turn

Methods of holding your work while shaping it – pros and cons

A faceplate fastened with sturdy screws is your most secure (unless the imperfections prevent) method if the wood is flat and you can lock into solid wood. The problem with this technique is that you lose control of your design options – ability to adjust alignment or easily tilt the work axially – when compared to a centre-to-centre between method. You cannot move your piece on- or off-centre, on or off a feature you want to highlight, even out a natural edge bark alignment or position a natural hole or inclusion to create a balanced design of your desire.

Also, if the wood is soft and it happens to be in the area where you need to fix the faceplate, the screw holds will not be secure. Centre-to-centre – between centre holding – is often the go-to holding option for many  turners when shaping and designing the outside and to create a tenon for final holding.. To accomplish this, find what you assume to be the centre of the top and bottom of your piece. Gently tighten the wood – between a drive spur and revolving centre – and when secure between centres, rotate the piece by hand 1/4 of a rotation to see how the piece moves on its own.

If the piece is out of balance, it will rotate and rest with the heaviest section downwards. Adjust the centre positions so that you can minimise this out of balance aspect and then rough shape the wood creating the mounting method of your choice for turning the inside. If you use between centre method, you can adjust the centre positions and manoeuvre the work so you can see the most figuring or highlight a feature to the maximum.  Although this may create an imbalance in the wood initially, you gain that special look with the wood on your work. A screw chuck or four-jaw chuck with screw chuck insert in another option. If the wood is already flawed or soft it may not allow the use of this method, but if you so find a secure screw hold in solid timber then this method can work.

A glue block (turn a concave area met with a glue block that also has a concavity, using thick CA glue for the union) is an option but solid flat faced timber is needed. This method is better looked at after the initial shaping is done. Again, this depends on the imperfections you are presented with as to the security for the hold. If you are using this method on rough-turned blanks I have a series of different sized ‘permanent’ glue blocks that I have been reusing for three years.

I have drilled a 2mm hole in the centre of the block and use a metal coat hanger to find centre on the piece to be glued. Place a ring of thick CA glue around the rim of the area on the piece to be joined, spray activator on the block area being joined, and then slide the block onto the piece using the coat hanger as your guide (thank you Lyle Jamieson for this tip!). Again, it fixes a blank in a given position and does not afford easy adjustment of alignment.

Once your final holding method has been determined, make use of the tailstock to provide additional security when holding your work and remember to tighten everything up nicely before you begin truing up. As you do so, the balance will need to be checked and adjusted periodically. Once you are trued up (and any vibration is eliminated or minimised) examine your imperfection locations and place any holes, inclusions, bark balance on a natural edge piece, or wood discoloration in a position of your design choice. Once your decision is made, readjust the position of your piece to achieve this design, slow your speed until you are trued up one last time, then increase your speed to your comfort level and begin shaping the outside.

Once satisfied with your rough shape and design and have selected your final holding method  turn the inside – I chose a spigot to fit in a chuck for my 355mm bowl – turn the inside to a rough shape and set aside to dry/season. Once dry, the wood can be worked with straight away, you are ready to harden
or treat the soft areas. 

The initial mounting of a blank between centres
An example of a glue block union being positioned on an already rough-turned bowl. This method could be used to mount a new blank of wood ready to be turned
TOP TIP

One thing to bear in mind is that faster speed and slower cutting will usually result in the best cuts. The speed selected is a function of safety and no vibration. Adjust the speed to a safe level to suit the size and condition of the wood to the point that you remove completely or minimise the vibration induced by the work as far as is safe to do so.

The good soak

Soft or punky areas of wood – note the word ‘areas’ – can often be sorted out with a good soak of a solution or fluid that will harden the wood. The ‘soak’ I find most effective is to saturate your piece with a wood hardener. My go-to wood hardener is the High Performance Minwax Wood Hardener. Having said I use a specific wood hardener, it is worth noting that there are numerous alternative brands of wood hardener.

Here are a few others available: Rotted Wood Repar-PC Petrifier, Lee Valley Liquid Wood, Drechseln & Mehr Wood hardener. These are either brushed on to flood the affected areas or coat the whole piece. Although more expensive – the need for more product – work can also be dunked in a tub/bucket of the solution to soak it completely and left to dry. Multiple coats/dunking can be done too. The objective is to harden the wood and make cutting it easier.

Saturate as the product recommendations and/or needs dictate, but effectively do this until you see absorption has just about finished. Allow the wood to dry fully before continuing. The drying times will vary depending on the product used. The bowl I treated – a punky 355mm diameter bowl – took two days to dry and absorbed 1ltr of hardening solution.

  • Alternative methods for treating small areas are:
  • Rub warm water on the affected area
  • Apply thin or medium Cyanoacrylate adhesive glue
  • Treat the wood with thinned down sanding sealer
  • Use one of the many thin free-flow epoxy products available now.

It is worth noting that some treatments can colour the wood or certainly darken them considerably, so please bear this in mind; when working and if in doubt, try the product you have on a small area. If you are patch sealing and the wood does change colour significantly the patch may show up as a distinctly different area. If this looks wrong when contrasted to the untreated area, treat the whole work with hardening solution or treatment to unify the colouration.

Note: If a patch of wood is only slightly after than the surrounding areas, some people just apply a very light coat of oil or wax to that area and then make a cut. Warning! This application of oil or wax can affect any final finishes applied later on. But, for very small areas, this method can work well. 

This bowl has had complete saturation of wood hardener all over
The saturated and hardened dry bowl ready to work with

After the wood is hardened or treated

Now comes the stage for turning the wood to what is (hopefully) a decent finish, prior to sanding and coating it with a finish of  your choice. Once the hardened wood is dry I chose to mount the work between centres and refine the outside – typically using a push cut – then adjusted the tenon size to suit my chuck jaws or glue block and set about finishing the outside shape and then turning the inside. Remember I mentioned chucking and holding work to turn the outside?

The same considerations apply to holding the work while turning the inside. You need to select a holding method that will keep the work securely at one end while turning the inside. Even though you have hardened the wood in some way, all of the potential problems with faceplates and glue blocks mentioned earlier hold true, and if you opt – as I did – to use a four-jaw chuck, make sure you can lock onto solid sound timber and that the spigot is large enough to hold the work properly without the risk of shearing across the tenon or recess wall when turning. Typically, we look to have at least 35% of the overall diameter to hold in a recess or spigot to minimise the shear risk. That said, always use the tailstock in place for extra security no matter what method you use and only remove it once it gets in the way.

Initial mounting of the hardened rough-shapes bowl between centres in order to refine the outside shape

Tools to refine work

The tools and their use in stages (good to better) of perfecting the smooth cut are: a 15mm bowl gouge, 10mm bowl gouge, a 6mm bowl and/or spindle gouge and cabinet scrapers. The use of cabinet scrapers freehand on turning is deemed by some to be dangerous. In reality, as with using conventional turning tool scrapers, the biggest issue is avoiding dig-ins by taking too heavy a cut, presenting the cutting edge upwards into the oncoming wood, in the case of square across or angled scrapers of any sort, touching any of the pointed ends into oncoming raised work or chucks – especially if titled upwards.

By using a trailing angle, keeping clear of upstanding detail and spigots and chuck areas, the trailing freehand action of using cabinet scrapers can work well. Remember, that this method is never used in conjunction with a toolrest; the scraper is always pointing downwards in the lower half of the work and only ever sharpen one edge of the blade – the one being in contact with the wood. If you sharpen all edges and slip or run your fingers across the non-contact edge then you can cut yourself.

If this method is not something that you would like to use, try using a conventional scraper or negative rake scraper used in conjunction with the toolrest on a waste bit of the bowl, to see of you can or cannot get a finish. If you can, turn your work using gouges – looking at the methods mentioned below, then go to scrapers if you think you can refine the surface a bit more – if not, go straight to abrasives after the gouges have been used.

Sharp tools are the key to a smooth cut

It is never too repetitive to stress the need for sharp tools. I have found the best ‘finish’ for me in sharpening comes from using CBN wheels. Others will have varying opinions on what is best for them, but whatever you use, sharp edges are the key to success. I use an 80 grit for shaping and 180 grit for fine sharpening, or better said, touching up the cutting edge. Sometimes I hone the cutting edge, but that is not necessary at the beginning stages of your project. Before my ‘finishing’ shear scrape, I retouch the cutting edge on my 180 grit wheel and then create a burr on the side of my gouge/cutting edge that is doing the work. 

Selection of the tools I use to shape my work
Variously shaped cabinet scrapers

Cuts that will make a difference

Depending on the individual piece of wood you are working with, push cuts are usually the go-to cut to start with. The keys to a good push cut is a sharp tool, body/foot balance so that you are in the most comfortable position at the end of the cut, speed up on the rotation and cut slowly and thin (say 3mm) cuts. As you can see, the results are amazing. The pull cut can also be used and the effectiveness is dependent on the particular character of the wood. Shear cutting is different from shear scraping. It might well help eliminate torn grain. If the imperfections/tear out still exist, try your conventional grind bowl gouge and then downsize to a 6mm bowl and/or spindle gouge.

Shear scraping with a gouge. Once you are down to your desired thickness (plus a fraction for final cut and sanding) and design, apply a water soak and create a burr on your bowl gouge. Position your body parallel to your piece, move your body with the scrape and then cut, lightly holding your gouge with your fingers, not your hand (as if you were painting the Mona Lisa) and cut as if you were shaving a peach. This requires the highest speed to your comfort, 90–95% tool weight on the toolrest, slow and shallow cuts and moving your body, not your hands, as you cut. Your shear scrape cutting edge should be approximately 80–85° facing the cut, handle almost straight down and make a slow light ‘shaving’ scrape.

Shear scraping with a cabinet scraper

If there are any remaining imperfections, create a nice burr on your scraper, apply a water rub and while your lathe is at its highest safe speed for the size and condition of work and your comfort level, apply the scraper with the lightest of touches at an angle of 45° to the wood. Glide it from the bottom of the piece to the edge.

A pull cut is an option to remove bulk, but is not as good at refining a surface as a push cut
The push cut is the go-to cut for optimum shaping and refinement
A shear cut is a cut that may – or may not – improve upon a push cut as good at refining a surface as a push cut
A gentle shear scrape with a bowl gouge can help eliminate punky timber and grain tear out
Cabinet scrapers can be used to great effect, but if you are unsure about freehand scraping, use a conventional scraper placed on the rest and presented in shear cutting mode or use a dedicated angled shear scraper to remove minor imperfections
A warm water rub used before a final scrape cut
The results of two scrape cut passes after a warm water rub

Conclusion

I have tried to show a few routes and methods to work with soft and punky timber, but despite our best efforts things can still not come out right. Remember, work as safely as you can and always within your ability limits. If imperfections still exist and you are not pleased with the look at the end of the project, throw the darn piece of wood in the fireplace! Life is too short. 

Leave a Reply

Your email address will not be published. Required fields are marked *