Polishing spalted wood

[Grahamshed]

I have an idea for something I want to turn and I have a piece of wood just the right size but it is spalted Silver Birch and I want this piece to take a really high shine.
So questions are....
1. Will spalted wood take a high shine like 'ordinary' wood will ?
2. What substance and methoud would you suggest to achieve it ? ( I will buy the Chestnut buffing system if need be, it will get used for other stuff as well )

 

[Bodrighy]

If you sand the piece when finished to at least 400, give a coat of sanding sealer and then burnish with shavings immediately on the lathe at speed it will give the surface a fairly hard finish that can then be polished to a good shine. Also go back a couple of times between buffing to buff again with your polish.

Pete

 

[Spindle]

Hi

Spalted wood will take a good finish but:

Depending on how far he spalting has progressed you may have soft corky areas - these will need to be stabilised with sealer or CA as you turn. Once the turning is finished apply sanding sealer, (thinned will aid absorbtion), until an impervious surface is achieved and then sand through the grades applying more sanding sealer if necessary.

I don't buff my work so will defer to others re that part of the process.

Regards Mick

 

[CHJ]

Silver Birch is a relatively soft surface to start with, being spalted Silver Birch, will probably put you at the worst end of the curve possible as far as obtaining a sustainable polished surface on the wood alone.

But as said if you seal the surface well and establish a hard surface shell it will be this that you are burnishing and polishing so the underlying wood has no bearing on the ability to achieve a high gloss finish.

The ease with which the soft under surface can be damaged from knocks and wear and tear if it is to be a user as opposed to just a display piece is another matter of course.

 

[Grahamshed]

Thanks guys. I am having serious doubts if this is going to be the right wood for the job. I may find something else.

 

[Random Orbital Bob]

another thing to be aware of with the more punky bits of grain in spalted woods is the different rates they yield to sandpaper. The softer areas tend to abrade faster than the harder areas next to them. I find if I soak the punky bits with watery CA (the cheap poundland stuff) it firms it up so it sands at about the same rate as everything else. While the CA is wet, you can also sprinkle a handul of very very fine colour matched sawdust which acts like an aggregate and fills the hollows and flaws. I would say I get more consistently hard surfaces using ca than I do with sanding sealer alone. The ca seems to really knit the punky wood together. If you do add the dust though it will always show in the final polished piece even though the surface will be uniform and polishable.

If there is a lot of really punky grain I tend to ditch them now as it can be a lot of trouble.

 

[winemaker]

burnish with shavings immediately on the lathe at speed :?:

never heard of that :mrgreen: how do you it :mrgreen:

 

[Random Orbital Bob]

grab a handful of the shavings under the lahe and semi grip the workpiece with them in your hand but watch your fingers obviously. The heat and abrasion of the shavings harden the outside layer of sealer making it more suitable for polishing.

 

[Bodrighy]

Burnishing the sealer with shavings gives it a hard finish which may help with the softness of the wood. Use the sealer diluted ideally, about 50/50.The end result looks polished but buffing afterwards takes away the slightly varnished look and gives that deeper gloss that is (IMHO) far more attractive.

Pete