Pencil marks on sealed deck

[anton13]

We recently had our timber deck refurbished with new garapa decking boards. Unfortunately, the contractor did a shoddy job, and (amongst many other problems) neglected to clean the pencil marks before sealing. When I asked him about this, he said that pencil marks will simply go away by themselves.

* Is it true that such pencil marks will fade away completely, and how long does it take?

* Is it possible to remove pencil marks from sealed hardwood, without further damaging the deck? (For example, without discoloring the sealant?) I've read on other webpages that mineral turpentine and acetone work well for removing pencil marks. However, I'm not sure if this advice also applies to sealed wood.

According to the specifications of the sealant, it is compatible with mineral turpentine, but not with acetone, and turpentine is also used to clean the wood between applying coats:
Compatibility:Mineral Turpentine. Non-Compatibility:Acetone, Lacquer Thinners, Benzene and other solvents.
Apply first coat until surface remains evenly glossy for at least 10 minutes after application. Apply more product to dull/dry areas. Allow coat to dry completely. Sand lightly with steel wool. Remove dust with clean, dry cloth. Then wipe with mineral turpentine. Apply two more coats in the same way. I therefore hope that it may be possible to clean the pencil marks with turpentine, perhaps followed by a touch-up extra layer of sealant.

[russ57]

Speaking purely theoretically here.
I wouldn't expect pencil to fade. It's basically graphite /carbon.
I doubt it could be removed without removing sealer.
If you know exactly what the sealer is, then in my thinking, you could sand the marks out and reseal. If it is done very soon, before the finish fades / discolours then the repair should be not visible.
If the boards were stained a part of the finishing process then it could be much harder.
Or I could be wrong...
Is there a hidden area you can test on?

[Skew ChiDAMN!!]

Pencil marks won't fade. Given enough time the deck will weather and the marks will disappear because the surface is sublimating away. But that's a completely different thing and, unless you want the deck to silver, probably not acceptable.

If the deck was sealed very recently, you may be able to get away with using a suitable thinner and rag to wipe away the sealer and, possibly, the pencil marks. More likely you'll need to lightly sand; depending on the type of sealant you may be best advised to wait a few days or six after final application for the sealer to cure before attempting to sand it. Otherwise it can be like trying to sand wet paint. "Gluggy" and wasteful of sandpaper.

Whether any future spot applications of the sealant will bond to the existing coat is yet another matter. Russ57's suggestion of testing a hidden area first is spot on... if possible, of course.

Really, it all depends on just what specific brand and product was used, which you haven't mentioned. That wee little bit of info can make all the difference in the world between "Oh, it's easy" and "Sorry. You're flat outta luck."

[anton13]

Thanks for the replies!

The sealer that was used is Woodoc's Totim Exterior Wood Sealer (https://www.woodoc.com/en/products/woodoc-totim-exterior-wood-sealer-solvent), which the manufacturers themselves confirmed to me is completely unsuitable for use on decks.

The phony deck builder used far too little of the product for a proper seal -- not even enough for two coats. This may a blessing in disguise, since it will hopefully be less difficult to remove the pencil marks, and then apply additional coats of a proper deck sealer.