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For years I've used Bostik TopCote (apparently now called GlideCote) to protect the cast iron top of my table saw. It has always worked very well: I have no rust on the top, and it provides a nice slick surface. But now my can is empty! Before I spend $20 on a new can, I'm thinking about other options.

Looking around my shop, I've got at least two cans of clear Briwax with little hope of ever using them up in my lifetime. I've heard of people using beeswax on cast iron, so that might be an option. Do I need to be concerned about wax applied to the table surface rubbing off on workpieces, possibly causing finishing problems? Does a wax coating last, and does it provide adequate protection against corrosion?

Are there any other protective coatings for iron that I should consider?

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    I use Silicone spray, I've been told both that it does and does not come off on your wood. I spray it one once or twice a year rub it down and I've never had problems with it – bowlturner May 15 '15 at 16:54
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Various people swear by different rust prevention products for cast iron tops, but unfortunately not everyone is able to achieve the same results. In 2012 Fine Woodworking did a torture test on tool steel and cast iron, and found that many popular "tried and true" rust prevention products did ok on tool steel but many did not perform as well on cast iron. Some of the results even seemingly contradicted the previous results published in FWW--for example, a different article highly recommended camellia oil over anything else, but in the torture test many other treatments outperformed it, even on tool steel. In fact, if you look at the Amazon reviews for the products that did do well in FWW's test, you'll see that many people's results were inconsistent with Fine Woodworking's findings. Unfortunately, there's no guaranteed winner.

Silicone-free paste wax is a common recommendation. Silicone can come off on your wood. If this happens, it can cause birds-eye spotting when you go to apply finish, and according to George Vondriska of the Woodworkers Guild of America, it can also prevent glue from adhering properly.

The typical recommendation for any type of protective finish is to strip and reapply protectant every 2-3 months. If you're in a humid region, I'd suggest going no more than 2 months. If you're in a dry region, you may be able to go a long time.

Personally, I've been using Boeshield T9, which is a pain because it dries tacky and requires a coat of wax on top to allow wood to slide smoothly. I'm not convinced T9 is any better than any other treatment. Even with that double treatment, my saw top started to show light rust in one place after just barely 2 months. However, I reapplied after removing the rust, and through the entire following winter it was fine without any additional treatments.

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As far as rust-prevention goes, I would caution being very sceptical about the results of published comparative tests. Every one I've seen done by a commercial publication, without a single exception, would fall short of a proper scientific comparison. Some even acknowledge this in the text!

So they are far from definitive and the wildly differing results for the same products should throw up warning flags. In one test WD-40 did very well indeed, despite its known weakness as a long-term rust preventative. In another BoeShield did poorly — for one reason or another — when it is widely acknowledged by professional users to be one of the best products there is (not an endorsement of BoeShield by the way).

If we go back to the era before modern scientific coatings and see what they recommended it was oiling or greasing (e.g. with tallow) or waxing. All of those are still viable ways to go for rust prevention. From user experience they all work when upkeep is maintained.

But for rust prevention and surface glide IME there's a clear winner: wax.

If you leave enough oil or grease on the surface that it's as slippy as a well-buffed wax coating it'll be actually greasy, which is all sorts of bad. Apart from the obvious risk of getting wood greasy from direct contact, your fingertips can get oily and transfer this then to the next piece of wood you handle. And to top it off, with that amount of oil on the surface dusts of all levels will cling to it.

So wax it is. Paste wax specifically. Before you run out to buy any it's incredibly easy to make at home, cheap too. All that's required is wax to be melted with spirits or turpentine (or dissolved in the solvent in a warm spot like a sunny windowsill), poured into a suitable container and left to set. That's paste wax, indistinguishable from many commercial varieties except for colour, and possibly smell.

Waxes to try:

  • Paraffin wax (as in most white dinner candles, in North America canning wax is another source). Usually far and away the cheapest option.
  • Beeswax. slightly tougher but more expensive.
  • Carnauba wax, which is very hard. Not to be used by itself, but as an additive to make the dried wax coating harder.

So for the cheapest coating with good wear resistance use paraffin wax mixed with a little carnauba.

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