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+-- Thread: Does oak tannic acid destroy steel fasteners? (/showthread.php?tid=7345240)
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Does oak tannic acid destroy steel fasteners? - Lonnie in Orlando - 12-26-2018
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
RE: Does oak tannic acid destroy steel fasteners? - Bill Holt - 12-26-2018
I have no answer for the original question.
My first concern is the use of dowels. If a screw is used in that same area, it will be in end grain. One option might be plugs, but plugs are short so the bottom of the hole could be filled with epoxy.
Of course, after restoration, the car will receive much better care than it did toward the end of its current life.
I restored a 1963 Chris Craft many years ago; mahogany and brass screws were my challenge.
RE: Does oak tannic acid destroy steel fasteners? - Lonnie in Orlando - 12-26-2018
Bill,
I had the same concern about end grain. I considered drilling with a Forstner bit and cutting ash plugs with a plug cutter. Don't know if I could cut them long enough (deep enough). If I can, then I suppose that epoxy would secure the tapered plug solidly enough to hold a screw(?). A previous owner used brass screws in a partial restoration. They held up well, but the heads were pretty butchered from installing and removing. I prefer a stronger material - but brass is an option.
Thanks,
Lonnie
RE: Does oak tannic acid destroy steel fasteners? - Stwood_ - 12-26-2018
Once the oak is dry, and stays dry, the eating of fasteners is no concern.
On the future plugs, I would suggest buying a plug cutter and making your own. I think there are cutters out there that cut them about 3/4" in length.
RE: Does oak tannic acid destroy steel fasteners? - hbmcc - 12-26-2018
Nice tires!
I think if more wood species were used in museum storage, the list of reactive woods will be longer. Oak is favored for furniture, so it gets the rap sheet. Obviously, as you found, Ash shares culpability.
If you can seal the contact area between wood and metal the corrosion should be minimized. Epoxy is good for that. And, yes plugs are better than end-grain dowels. The dowels could fail too. I think you are facing 60 years of corrosion. Any correction you make will last at least a third as long.
Are the ash frames too weathered? Should they be replaced?
RE: Does oak tannic acid destroy steel fasteners? - Wild Turkey - 12-26-2018
Remember there is “stainless steel” and there is “stainless steel”
Town where we live built a SS sewage plant but somewhere between “good idea” and construction someone changed the type of SS and ten years later it was useless due to rust
Point is some SS screws are soft but others should be harder
With the work you’re putting into this I’d make sure it stays fixed
RE: Does oak tannic acid destroy steel fasteners? - Rodneywt1180b - 12-26-2018
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.
RE: Does oak tannic acid destroy steel fasteners? - museumguy - 12-26-2018
(12-26-2018, 05:31 PM)Rodneywt1180b Wrote: 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.
Hmmm, I never would have thought of that. I think it is a great idea.
RE: Does oak tannic acid destroy steel fasteners? - AUswimKC - 12-26-2018
Jason Thigpen of Texas Heritage did something similar recently. He might be a good source to bounce ideas off of
RE: Does oak tannic acid destroy steel fasteners? - Timberwolf - 12-27-2018
(12-26-2018, 10:00 AM)Lonnie in Orlando Wrote: 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
Make your plugs out of teak...it's about as good as it gets...I would use bronze screws...why not go for the best.