Does oak tannic acid destroy steel fasteners?

[RobertJ25]

I believe that eventually the acid will corrode the screws.   I have  picnic table that is an example.  Around the turn of the previous century,  as the oil fields of the Allegheny mountain area of Pennsylvania were being developed,  oil was stored in above ground cylindrical tanks made of redwood.  Eventually these tanks were replaced with steel.  I had an uncle that lived in the Rixford Pa. area who salvaged some of this redwood, and , being a woodworker built picnic tables for family members with it.  This would have been around the middle of the last century, or about 70 years ago.  My father-in-law had one and after he passed,  it came to rest on my deck.  I discovered that over time,  the steel fasteners which he used corroded,  and rotted the wood in their immediate vicinity.  Its heirloom value has motivated me to rebuild it,  and I hope my son  enjoys it some day.    
Bob

[Phil S.]

Given the amount of time and money you're going to have in it I would go with marine grade bronze screws.  Drill your holes and use a same sized steel screw to cut the threads then install the bronze ones permanently.

I agree.  Here's a source -

https://www.jamestowndistributors.com/us...nze+screws

Also agree with using plugs instead of dowels.

[DaveR1]

It's common knowledge among builders of wooden boats that oak and steel are not a great combination. The tannins will react with the iron in the screws and create problems. Do a search for "iron sickness in oak". Although your car won't be out in the wet like a boat so you would just slow down the process a bit. I would second the bronze screws.

Also, if you are going to plug holes, don't use dowels. Use plugs with face grain on the ends and make them of the same wood species you are plugging. Align the grain of the plugs with the grain of the piece with the holes. (I have an easy method for inserting plugs with the grain oriented correctly if you're interested.) If the holes are too deep to fill with a plug, use a dowel but seat it far enough below the surface that you can insert a plug over it. If you are plugging over screws, don't glue the plugs in. Use the varnish or whatever you'll finish the wood with to secure them. The plugs will stay in place just fine but are easier to remove without damaging the surrounding wood if there's ever a need to remove the screws.

[Phil S.]

I had another thought (Holy mackerel - two in one day! 
 ).  If you're worried a plug is too short, put in several.  Should work with straight sided plugs.  LV, among others,  makes such a plug cutter -

http://www.leevalley.com/us/wood/page.as...,180,42288

These cut plugs an inch long which may be enough using just one.

[Farwood]

I'm restoring a 1955 MG TF-1500 British sports car.  It has an ash structure onto which the body panels are nailed.  (yes, that's right - they are nailed)  The ash pieces are screwed together.  Some of the screws holes are stripped and no longer hold the screws.  I drilled and plugged the holes with red oak dowels.  The wood and the dowels will be sealed with clear penetrating epoxy sealer, which should stop water entering the pores of the red oak.  I prefer to use steel screws vs stainless steel because I feel that they are stronger and period correct.

> Will tannin in the red oak destroy the steel screws over time … 20+ years?
> Can the tannin be neutralized?
> Should I bite the bullet: Turn some ash dowels, drill out the red oak dowels and replace with ash?
> Suggestions?

Thanks for your help,

Lonnie

I've restored oak furniture that was over 100 years old and assembled with uncoated steel screws.  There was no issue with unusual corrosion, but then they weren't sitting in a humid garage.   Modern, plated or coated fasteners should not be an issue.  Still, using bronze screws wouldn't be a bad idea.

[Stwood_]

Here is some machine cut square nails that came out of a 125 year old soft brick building, that the roof structure was white oak.
There is surface rust only. Absolutly no damage to the nail from oak acid.
Some of the oak was rotted around the edges from water damage over the years.
Sorry for the less than perfect pic.

   

[Cooler]

Back in 1965 my best friend Bryce bought a 1951 MG TD.  It had, as yours does, a wood understructure.  Some of it was rotten.  

Bryce's father got us some wood and a coping saw and a couple of rasps and we copied the pieces and made all new.  

If you are doing a restoration, I suspect you can do better than we did when we were 16 years old.  I would make all new pieces.  I would use ash as was original.  The old parts are the template.  

I'm sure a band saw is going to be faster than us working with a coping saw.  We spent hours coping out some of the parts.  Mostly we did the frames near the rear where the convertible top attached.  We did not replace all the wood.

Note:  Bryce's father was good enough to give me lessons in the car along with Bryce.  So I learned to drive on the 1951 MG which had no directional signals.  All the signals were done with an arm out the window.  To this date, whenever the weather is nice and the windows are cranked down in my car I end up using hand signals.  While they are legal, I suspect it is not very safe as most people will not notice the hand signals.