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What happened to my table saw top?

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Forum topic by triskal posted 01-13-2018 06:05 PM 1960 views 0 times favorited 18 replies Add to Favorites Watch
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triskal

8 posts in 283 days


01-13-2018 06:05 PM

I have a Delta contractors saw that I got recently cheap on Letgo. Among other things the top needed cleaning. I got it in pretty decent shape – not restoration quality but pretty good. I used Boeshield T9 to lubricate and rust-proof and then paste wax to make is slippery. This was all done a while back when the weather was warmer and immediately afterwards had no problems.

I’m in N IL. It has gotten much colder lately from below 0 to the teens. A few days ago we had a warm spell in the upper 40s. The garage is not insulated but does have drywall. I fired up my portable propane heater and got it decently comfortable. However it was very humid having been raining on and off for the day.

I was working on a small project and found that the top of my saw was leaving dark stains on my wood (oak) that almost looked like mold. A close inspection of the top revealed a yellowish film that to the touch was a bit grimy. I wiped i mostly off so you can’t see it anymore but the top still feels rough.

Does wax react with the temperature and high humidity to do that? I assume I can just clean with mineral spirits and start over?

Thoughts?


18 replies so far

View Loren's profile

Loren

10477 posts in 3764 days


#1 posted 01-13-2018 06:08 PM

Sounds like rust. Clean it off and re-wax.

View triskal's profile

triskal

8 posts in 283 days


#2 posted 01-13-2018 06:13 PM

Maybe but it was more yellowish than rust colored. Plus I had previous TS with a cast iron top that I kept treated with T9 and never had a bit of rust. That combined with the wax seems likely to prevent rust in the month it has been since I cleaned and treated it last.

I am sure I can clean it up and redo it without much trouble. It just took me by surprise so I am curious what happened.

View MrUnix's profile

MrUnix

6886 posts in 2315 days


#3 posted 01-13-2018 06:20 PM

... I had previous TS with a cast iron top that I kept treated with T9 and never had a bit of rust. That combined with the wax seems likely to prevent rust in the month it has been since I cleaned and treated it last.
- triskal

FYI: T-9 is just wax (paraffin) + mineral oil in a mineral spirits carrier
Johnsons Paste wax is wax (paraffin, carnauba and microcrystaline) dissolved in naptha

Key ingredient is wax. Boeshield just charges you more for it :)

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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TheFridge

10092 posts in 1602 days


#4 posted 01-13-2018 07:22 PM



Sounds like rust. Clean it off and re-wax.

- Loren

Even if it isn’t. It still needs to be cleaned.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View jerryminer's profile

jerryminer

942 posts in 1558 days


#5 posted 01-13-2018 08:02 PM

I think Loren’s got it. The propane heater added to the humidity (because water vapor is a product of combustion) and the oak turned black when the tannin in the oak reacted to the iron in the rust.

Clean and re-wax.

-- Jerry, making sawdust professionally since 1976

View bonesbr549's profile

bonesbr549

1576 posts in 3183 days


#6 posted 01-13-2018 09:55 PM

I’d strip that off and just put some johnsons paste wax. I put some T9 on my SS and it was a mess same issue. Stripped it off with MS and put just Johnsons paste wax no issues.

Thats my two cents worth, but that and a buck fifty will get you a cup of coffee. Cheers.

-- Sooner or later Liberals run out of other people's money.

View Woodknack's profile

Woodknack

12331 posts in 2496 days


#7 posted 01-13-2018 10:30 PM

Strip off the wax and whatever else with naptha and a green pad then put on a coat of waterbase polyurethane. Wipe on a very light coat. Optional: once dry, use a light coat of wax to make the top slicker. The poly will wear off but lasts a lot longer than any spray or wax.

-- Rick M, http://thewoodknack.blogspot.com/

View Walker's profile

Walker

146 posts in 588 days


#8 posted 01-14-2018 01:53 AM

Stupid question time… I have a cheap table saw with a cast aluminum top, not cast iron. Obviously rust is not a concern, but will all of these products suggested work just as well to keep it slick? Any I should avoid?

I’ve rubbed the miter tracks with paraffin wax before (an old candle), which seemed to work well enough but tends to attract a lot of sawdust.

-- ~Walker

View MrUnix's profile

MrUnix

6886 posts in 2315 days


#9 posted 01-14-2018 02:20 AM

Waxing aluminum tops is fine and will allow the wood to slide over it easier. I have always given them a good coat of paste wax every now and then when needed. It does not (or should not) attract dust as it is a hard finish. BTW: Aluminum actually does rust (oxidize)... although it’s white, not red/brown like that on iron.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View Woodknack's profile

Woodknack

12331 posts in 2496 days


#10 posted 01-14-2018 02:34 AM

Aluminum does oxidize. But I had a bandsaw from the 50s with an aluminum table and it was fine. A layer of oxidation will actually protect it from further oxidation.

-- Rick M, http://thewoodknack.blogspot.com/

View jerryminer's profile

jerryminer

942 posts in 1558 days


#11 posted 01-14-2018 02:59 AM

I like paste wax better than paraffin because 1. it’s easier to get a consistent thin layer on the table, and 2. once the solvent evaporates, the wax left behind is harder (contains carnauba—a hard wax) than paraffin (not sticky).

Yes, wax works with aluminum as well as cast iron

-- Jerry, making sawdust professionally since 1976

View CaptainKlutz's profile (online now)

CaptainKlutz

447 posts in 1611 days


#12 posted 01-14-2018 10:14 AM

Do not forget about evils of condensation!

Cold cast iron in a warm moist garage will collect “dew” on the surface almost instantly.
Unless your surface treatment is 100% sealed protection (IE primed and painted), you will get formation of moisture causing rust on cast iron surface until the cast iron is above dew point for current humidity level.

With zero wax or other protection, you can even get “flash” rusting – meaning clean at start to light rust oxide when condensation moisture dries an hour later. Lived in Missouri long ago, and was horrified one time to see my waxed cast iron saw and band saw tops were clean when I stopped on Saturday, and then wet+rusted on Sunday; sitting in an closed garage whole time? :(

Wax does a great job of slowing rust creation. But if your shop sees large cold to warm temp shifts with high humidity that creates condensation; you need additional protection on horizontal cast iron surfaces.

Simplest solution is to place a tight fitting cover directly on top of cast iron surface. They sell commercial magnetic table saw cover sheets intended to prevent condensation/rusting on cast iron. Can also use a simple 1/4” MDF or Masonite sheet. My cross cut jig is roughly same size as my cast iron top, and it works to stop condensation created rust for me. Goal is have the moisture condense on the cover and not the cast iron. :)

Also Second Rick_M suggestion: remove existing rust with sandpaper/oil, clean with solvent, dry, apply water base poly with a green scrub pad (helps to seal the cast iron pores where rust starts), When poly is dry – wax top with white scrub pad, and buff top smooth when wax is dry. Top will be slick and stay rust free for long time. You will notice more drag when you need to re-wax. For my casual weekend use, coat of poly lasts a year or two.

Do not neglect the tilt and height mechanisms when applying rust protection. Paraffin or bees wax on those adjustment gears and screws is needed as well. [Grease collects to much dust]

Best Luck.

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

View triskal's profile

triskal

8 posts in 283 days


#13 posted 01-14-2018 01:54 PM

Like I said I was surprised. Id never seen this happen before. I am hoping to insulate and great my garage next year though probably won’t run the heat continuously so this could still happen. Sounds like I have some work to do next time it gets warmer. We are back down to the single digits again.

Thanks all

View Markmh1's profile

Markmh1

84 posts in 560 days


#14 posted 01-14-2018 02:03 PM

The Captain nailed it.

A propane heater, for some reason, doesn’t seem to dry things out as it warms. A woodstove will warm and dry at the same time. I’ll bet the window was soaking wet.

Mark

View ChuckV's profile

ChuckV

3161 posts in 3644 days


#15 posted 01-14-2018 02:39 PM

I get this situation several times a year. I have found that just having properly shaped pieces of corrugated cardboard covering the surfaces prevents the problem. It is enough to keep the warm moist air from blowing directly across the cold cast iron when the temperature and humidity rise quickly.

-- “Big man, pig man, ha ha, charade you are.” ― R. Waters

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