How to get rust onto a sawtable - Pressure Treated wood

[Barry Vabeach]

I have seen a number of posts lately about how to care for a cast iron table saw top ( most rec. Johnson's paste wax) and how to get rust off a table saw top, but haven't seen any suggestions about how to get rust there in the first place and figured I might as well share how I did it. I ripped some pressure treated lumber. It wasn't that soaking wet kind, it was dry to the touch and fairly light. I couldn't get the project completely done by the end of the weekend, so I left a few of the pieces on the saw table - I went out of town for about a week, and when I went to move the pieces 2 weeks later, rust had formed under each one. Some was fairly superficial, but most of the rust spots were pretty deep. The table saw is maybe 2 months old, and had been regularly waxed - but I guess there was enough moisture in the lumber to cause the rust. Barry

[Cody Colston]

BTDT and have the rust stains on my TS to prove it. :)

[Stephen Tashiro]

Does the chemical that does the treating in treated lumber accelerate rust?

(And is treated lumber any softer than other equally wet wood? When I've made things out of treated lumber that were under moderate tension - like a post with a cord on it that holds a tarp - the lumber seem easily warped by the force. Of course I haven't built anything similar out of non-treated lumber, so an un-treated post might also have bent. )

[Jason White]

Pressure treated lumber, when bought new, is very wet.

It's fine to cut on your tablesaw, but be sure to blow all the sawdust off the top with a compressor or shop vac when you're done cutting.

Jason


I have seen a number of posts lately about how to care for a cast iron table saw top ( most rec. Johnson's paste wax) and how to get rust off a table saw top, but haven't seen any suggestions about how to get rust there in the first place and figured I might as well share how I did it. I ripped some pressure treated lumber. It wasn't that soaking wet kind, it was dry to the touch and fairly light. I couldn't get the project completely done by the end of the weekend, so I left a few of the pieces on the saw table - I went out of town for about a week, and when I went to move the pieces 2 weeks later, rust had formed under each one. Some was fairly superficial, but most of the rust spots were pretty deep. The table saw is maybe 2 months old, and had been regularly waxed - but I guess there was enough moisture in the lumber to cause the rust. Barry

[Larry Edgerton]

Does the chemical that does the treating in treated lumber accelerate rust?

)

YES! YES! YES!

There are specific fasteners that you have to use with the new formula of pressure treated wood as recommended by the manufacturer and required by BOCA. They are double dipped galvanized or stainless steel. It states that they are needed to stop fasteners from rapidly rust out and causing failure even when dry.

I will not cut PT on my primary saws, I have dedicated skilsaws and a disposable tablesaw, and on the rare occasion that I have to use a good tool I clean it immediately.

[David Christopher]

not only PT....I cut up a piece of burl last week to make a box out of and when I was through cutting I arranged the boards to see what a book match would look like and left the boards on the saw top...came back the next day after work and had rust and big black stains..I got the saw clean but it was really hard..just glad I didnt leave them for a long time

[Howard Acheson]

>> so I left a few of the pieces on the saw table - I went out of town for about a week, and when I went to move the pieces 2 weeks later, rust had formed under each one. Some was fairly superficial, but most of the rust spots were pretty deep.

Never leave any wood--pressure treated or not--on top of cast iron for an extended period. All wood has some moisture and even "dry" hardwood will damage cast iron. Of course, pressure treated is inherently quite "wet" even when it feels dry. Pressure treated wood sawdust inside the saw box can be problematic also. Best to clean out all residual sawdust when you've been cutting pressure treated.

Also, even sawdust left over night can cause problems. Last thing I do before leaving he shop is to wipe the sawtop and jointer top with my somewhat wax impregnated buffing cloth.

[Ron Bontz]

Well I fess up. The same thing happened to me. Only took two days though. I used a metal cleaner to clean it up on mine.:)

[Frank Drew]

I didn't know any better at the time and didn't completely clean the shavings from green wood turning off my lathe bed over night, and of course had rust in the morning.

And if you're doing any timber framing, don't leave your steel tools on the wood any length of time.

[Bruce Page]

Lesson learned the hard way.
I never leave wood of any kind sitting on cast iron for more than a few minutes. Even kiln dried wood has moisture in it.

[Jason White]

Potentially.

Modern PT lumber has some copper in it. That would suggest to me that there's the potential for corrosion due to dissimilar metals.

Jason


Does the chemical that does the treating in treated lumber accelerate rust?

(And is treated lumber any softer than other equally wet wood? When I've made things out of treated lumber that were under moderate tension - like a post with a cord on it that holds a tarp - the lumber seem easily warped by the force. Of course I haven't built anything similar out of non-treated lumber, so an un-treated post might also have bent. )

[Cliff Rohrabacher]

Yah rust is an issue with PT. The first large project I undertook with my brand spanky new sliding table saw was 9 of my Adirondack chairs.

I was squirting the thing with WD40 rather a lot.

The stuff is weird. It seems the pitch is plentiful and bonds to the water and copper and slings off the blade to form very hard tough piles on the saw in places you weren't expecting. Those piles start the rust. Even if they don't rust out they are tough as nails to get off.

Oh how to get the rust off:
Wire brush, scotchbrite, Bar keeper's friend is not my idea of the right approach 'cause it's got phosphoric acid in it. And you'll have tpo neutralize the acid.
You can with v baking soda and water and then douse it with high purity alcohol and then a fast treatment with Kero or WD40 (which is mostly Kero anyway) to drive off any remaining water the Alcohol didn't get.



If it's real bad: electrolysis: You can soak a terry cloth in soda and water and lay that on the rusty area and hook up your charger to that. Yes it really does work. Takes some fiddling with and attention.

[Neal Clayton]

PT lumber is another one of those things that i eventually asked myself "why do we use this stuff?" and yea i'll admit to using it myself.

but not anymore. red cedar is only marginally more expensive, is just as insect and rot resistant, and has the basic qualities desirable in wood like...you know...not rusting away my tools and the screws and nails i drive into it.