Lubricating screws into hardwood

[blackrose]

What would you use to lubricate stainless screws going into hardwood for exterior use?

 

I had a look on google and beeswax, silicone spray, vasaline are all recommended. I thought I might put a blob of plumber's silicone grease on each screw, or would a PU sealant be better to permanently prevent moisture being drawn into the thread by capillary action?

 

How To Lubricate Screws To Make Them Easier To Drive In - Australian Handyman Magazine

[Chagall]

Okay, I give up, not at all subtle. 

 

 

 

Edited March 23, 2021 by Chagall
self explanatory

[Tony Brooks]

The carpenters on the fleet when we had wooden boats used ordinary lithium car grease but I suspect that was to make them easier  to screw in rather than preserve them, and the screws were brass.

[David Mack]

I would have thought that PU sealant could make them harder to remove if you ever need to do so in future. And since wood is slightly porous, won't stop water wicking in. You would be better using brass, stainless or plated screws if rusting is a concern.

[BEngo]

Depends on the hardwood.  Teak and Iroko for example are already oily timbers so do not really benefit from lubricant.  

 

For more open grained timber like some mahoganies you want a lubricant where the oiliness does not wick out into the wood round the screw and show as a stain. 

Vaseline is OK and easy to apply, does not wick too much but see below if finishing.

 

At all events you want a lube that is compatible with any finish you are going to use.

 

Generally though decent stainless screws into a properly sized drilled qhole should go in dry, quite happily.   A2 and A4 grade stainless steel is tough stuff.  Unlike brass which needs a 'tapped' hole made by a steel screw first.  If you  can find them Torx or square drive screws are better than slotted or philips/pozi.

 

N

[blackrose]

57 minutes ago, David Mack said:

I would have thought that PU sealant could make them harder to remove if you ever need to do so in future. And since wood is slightly porous, won't stop water wicking in. You would be better using brass, stainless or plated screws if rusting is a concern.

 

Thanks, I am using stainless screws. See above.

 

26 minutes ago, BEngo said:

Depends on the hardwood.  Teak and Iroko for example are already oily timbers so do not really benefit from lubricant.  

 

For more open grained timber like some mahoganies you want a lubricant where the oiliness does not wick out into the wood round the screw and show as a stain. 

Vaseline is OK and easy to apply, does not wick too much but see below if finishing.

 

At all events you want a lube that is compatible with any finish you are going to use.

 

Generally though decent stainless screws into a properly sized drilled qhole should go in dry, quite happily.   A2 and A4 grade stainless steel is tough stuff.  Unlike brass which needs a 'tapped' hole made by a steel screw first.  If you  can find them Torx or square drive screws are better than slotted or philips/pozi.

 

N

 

Thanks, the screws won't be seen so compatibility of finish isn't really a concern. I think the wood is Iroko but I'm not certain. I think I'll just use silicone grease.

Edited March 23, 2021 by blackrose

[David Mack]

Sort of related...

Our previous house had been rewired at some time (before we owned it), with the switch drops using circular steel conduit buried in plaster, which seemed to be part of the original 1908 construction. The light switch in the hall had two switches - one for the hall light and one for the landing, and so two 1.5 mm2  twin and earth cables had been forced through the conduit, as I found out when I unscrewed the switch plate while decorating. The back box was half filled with a thick green goo with the look and consistency of swarfega. I reckon whoever had done the rewiring had used washing up liquid as a lubricant to get two cables in one conduit!

Edited March 23, 2021 by David Mack

[Man 'o Kent]

Wool Fat (Anhydrous Lanolin) can be bought from the chemist in a tub that will last a lifetime.

I've used it for years including on boats on the salty stuff and domestic too. Works a treat, screws drive in easier and lets face it when did you last see a rusty sheep?

 

It is good practice to pilot a hole for a screw with the right sized drill. The screw when being driven in then divides the grain of the wood rather than just forcing the fibres aside any which way. On the plus side a piloted hole provides a better thread and grip.

 

I have a chart somewhere in a very old book that lists the pilot sizes, I will hunt it out if anyone is interested.

[ditchcrawler]

48 minutes ago, David Mack said:

 I reckon whoever had done the rewiring had used washing up liquid as a lubricant to get two cables in one conduit!

I have done that.

[Tony Brooks]

55 minutes ago, Man 'o Kent said:

Wool Fat (Anhydrous Lanolin) can be bought from the chemist in a tub that will last a lifetime.

I've used it for years including on boats on the salty stuff and domestic too. Works a treat, screws drive in easier and lets face it when did you last see a rusty sheep?

 

It is good practice to pilot a hole for a screw with the right sized drill. The screw when being driven in then divides the grain of the wood rather than just forcing the fibres aside any which way. On the plus side a piloted hole provides a better thread and grip.

 

I have a chart somewhere in a very old book that lists the pilot sizes, I will hunt it out if anyone is interested.

I just put a vernier calliper on the base of the thread and pick the next screw size down.

[Opener]

1 hour ago, Man 'o Kent said:

Wool Fat (Anhydrous Lanolin) can be bought from the chemist in a tub that will last a lifetime.

I've used it for years including on boats on the salty stuff and domestic too. Works a treat, screws drive in easier and lets face it when did you last see a rusty sheep?

 

It is good practice to pilot a hole for a screw with the right sized drill. The screw when being driven in then divides the grain of the wood rather than just forcing the fibres aside any which way. On the plus side a piloted hole provides a better thread and grip.

 

I have a chart somewhere in a very old book that lists the pilot sizes, I will hunt it out if anyone is interested.

For repetitive screwing ( is that what I mean?) I just carry a well used bar of soap. Scrape the thread of the screw across the bar once which picks up a bit of soap - lubricates but is dry and not a liquid which may 'run'.

[jonathanA]

Seem to recall a joiner mate of mine of  using tallow on screws in hardwood

[Manxcat]

Paraffin candle wax on the screw threads.

Use proper wood screws, not modern multithread screws.

Use a steel screw to thread the pre drilled pilot hole,

Remove it and then replace with a brass wood screw to hold it together.

[blackrose]

The thing is it's for an exterior application and I also want the lubricant between the screw & wood to resist water so that it's not drawn into the wood by capillary action, which will prevent the wood from rotting around the screw. Surely things like soap will just be washed away during the first bit of rain? I'm still leaning towards a blob of plumbers silicone grease on each screw.

Edited March 23, 2021 by blackrose

[Opener]

On 23/03/2021 at 23:15, blackrose said:

The thing is it's for an exterior application and I also want the lubricant between the screw & wood to resist water so that it's not drawn into the wood by capillary action, which will prevent the wood from rotting around the screw. Surely things like soap will just be washed away during the first bit of rain? I'm still leaning towards a blob of plumbers silicone grease on each screw.

Hmm! I suppose my 'solution' was based mainly on internal works. But even externally the thread of the screw and the wood are going to be in very close proximity and the screw head - ?countersunk?? - should also seal the hole so I would hope there would be very little scope for washout. I'd be a bit concerned about silicone grease or similar viscosities being liable to wick to the surface around the screwhead and stain the surface over a period. I'm talking about using a pretty dry bar of soap so the lubricant is solid rather than liquid.