Wet Sanding of turning

[Willum]

I have seen several references to wet sanding but no advice on how it is carried out . I am currently doing battle with a piece of Laburnum which is very dusty and it sounds as if this would be the right technique so would be grateful for some advice on how it is done. I am more wary of Laburnum than most native woods as its toxicity is well known. I also have a larger chunk which one day may become something other than firewood, thank you, Bill Watkin.

 

[geordie]

bill it depends on what your finishing it with you can wet sand with oil

geordie

 

[CHJ]

Wet sanding is usually done on open grained woods to enable the resultant slurry to fill the pores and provide a smoother surface.

Would not consider it of any advantage on Laburnum, best precaution with this and any wood for that matter is to have high volume low pressure air flow extraction close to the workpiece.
If you have sufficient air flow volume to support and entrap the dust, you should see as a continuous smoke like stream entering the dust port.

 

[duncanh]

Also, if the laburnum still has the highly contrasting sap wood then avoid wet sanding as it will end up coloured but the sanding slurry. This goes for any other high contrast sap wood such as yew, mulberry and others

 

[Willum]

Thank you for your advice, I have a recently obtained HVLP dust and chip extractor and a separate Microclene air filter.
The piece of Laburnum seems to be some of the hardest wood I have ever worked and that includes a chunk of Lignum Vitae I have treasured but now almost used up. All points well taken, thank you again.

 

[chipmunk]

With all respect to Chas' comment I think there is another reason for wet sanding and that's to keep the temperature of the end grain down and prevent heat-checking. This is a particularly useful technique with yew and possibly also might be helpful with laburnum.

You can use oil or cheap paste wax or a mixture for this. A small brass bristled brush is useful to unclog the abrasive with wax and cellulose sanding sealer will easily cut through the wax used for sanding.

...but the comments about heart and sap-wood contamination are well made.

HTH
Jon

 

[CHJ]

With all respect to Chas' comment I think there is another reason for wet sanding and that's to keep the temperature of the end grain down and prevent heat-checking. This is a particularly useful technique with yew and possibly also might be helpful with laburnum.
......Jon

I take your point, but would submit that the practice is really masking a fundamental problem with sanding in that there is more friction than cutting taking place if the surface temperature is rising enough to cause checking.

Not trying to be holier than thou, we've all done the spoiling of a piece with too much heat but it is better to understand why it happens.

If you can sand with fresh sharper abrasive with less pressure it's an ideal, using water can be a better alternate if it's a must as there is no risk of subsequent finishes not bonding.

 

[chipmunk]

Hi Chas,
I take the point and agree but the problem with heat-checks is that they are practically invisible until you take the part off the lathe when they leap out at you

It is a belt and braces approach.

I'd question the use of water unless you only use acrylic SS/finishes or perhaps reserve it for just the coarsest grits? I'd be bothered about affecting the MC of my expensive timber and raising the grain too much.

Jon

 

[CHJ]

..... heat-checks is that they are practically invisible until you take the part off the lathe when they leap out at you .....

You want a perfect life, it's wood turning, why would you expect things to go right :shock: ROFL.

 

[chipmunk]

You want a perfect life.

Is there anything wrong with wanting it - Don't you? :wink:

I know it's a vain hope really. ...but it's what keeps me smiling and getting me through.

Jon