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I bought a Jarvis/Fully bamboo desktop and am trying to darken the finish. To do this, I first want to remove the existing finish. But I am having issues with doing so.

Note: pictures are at the bottom of this post.

I first sanded a corner on the bottom side. This took a long time (maybe 45 minutes), but it successfully removed the finish.

Since this took so long, I decided to try removing the finish chemically. I applied 3 coats of Klean Strip Premium Stripper to a portion of the desktop (not to all of it, so I could visually measure the impact of the stripper), waiting 15-30 minutes in between each coat and then scraping off the coat and wiping the wood down with steel wool and paint thinner. And yet, the finish looks no different.

Am I doing something wrong? Why isn't the stripper removing the finish?

Their website describes the finish:

We use Moso (Mao Zhu) species bamboo, sourced from sustainable forests

and

The bamboo we use for our desktops comes from sustainable forests where it's grown without pesticides or fertilizers and matures for five years. To preserve its natural beauty, we apply a tough UV-cured, water-based polyurethane coating.

After sanding the corner, but before applying stripper: After sanding the corner, but before applying stripper

Here is the stripper and scraper I used: Here is the stripper and scraper I used

30 minutes after stripper is applied: 30 minutes after stripper is applied

After removing the stripper. Note there is no difference! After removing the stripper

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    "we apply a tough UV-cured, water-based polyurethane coating" There's your answer right there. This stripper (in common with a lot of non-MC strippers) can barely handle a few modern coatings.
    – Graphus
    Commented Sep 22, 2022 at 18:44
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    "Why isn't the stripper removing the finish? If I must sand it, how can I sand it as quickly as possible?" This is two separate Questions and they should be asked separately. So I've edited out the sanding part. Do feel free to ask this as a new Q, but please provide more details about how you sanded up to now, and what you have available to you — no point in someone recommending a Deros if you don't own one! But in case it'll help point you in the right direction now, see What are the differences between sanding and scraping?.
    – Graphus
    Commented Sep 23, 2022 at 13:04
  • Since it looks like you won't need to ask the follow-on Q about sanding, out of curiosity what were you sanding with Chris? Even with the finish being clearly very tough 40, 45 minutes just to do that patch seems extraordinarily slow. I'm wondering if the paper type or grit, and/or the sander, were the likely cause.
    – Graphus
    Commented Sep 24, 2022 at 5:25
  • I was using cheap 40 grit sandpaper I bought off Amazon, and a cordless DeWalt orbital sander. But I tried sanding again and it took 20 minutes to go through the sequence of grits (the first grit that removes the old finish took 15 minutes of that time), so my original quote might have been inaccurate.
    – Chris Morris
    Commented Sep 25, 2022 at 18:54
  • Thanks for the details. I was afraid you were hand sanding initially (before I noted how round the end of the sanded patch was) and using a grit that was too fine :-) But somewhere in the region of 40 grit is definitely right where you want to be doing a rough-sanding operation (as long as you're careful, sanding is a very risky way to remove finish as a rule). Anyway, even with the caveats that this appears to be a very tough finish and the 40-grit paper was cheap this might still tell you something about the DeWalt sander.
    – Graphus
    Commented Sep 26, 2022 at 18:49

1 Answer 1

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Am I doing something wrong?

Technically no.

There are a few things you could have done that might have helped, but you did more than the instructions ask for. And from what we can see, you didn't do anything directly counterproductive (such as moving the stripper around when it's supposed to be sitting undisturbed, one of the three most common stripper faux pas).

Why isn't the stripper removing the finish?

Because it's not good enough for this finish. Kudos to Fully/Jarvis for choosing a really top-notch finish!

Although I'm familiar with its type I have no idea how good this Klean Strip stripper is overall. Despite the label specifically claiming it can work on epoxy and polyurethane1 many (perhaps the majority) of modern non-MC strippers barely touch, or seemingly have zero effect on, a few modern coatings. This includes but isn't limited to: UV-cured products as here, two-part urethanes, polyesters, epoxies and various "2K" finishes.

It is possible that if you could leave the stripper on for much much longer than directed (while keeping it from drying out) it could begin to work — in a similar situation I've had some success leaving a very generous coating of stripper on for a full day, twice2 — but this is much easier to arrange on smaller items.... and at the end of the day there's still no guarantee it'll do enough to make the effort worthwhile.

So what now?
If you do decide you need to continue to remove the finish (but see below) I suggest you do look at alternatives, principally scraping as I aim you to in the Comments above, assuming you don't want to try a different stripper type.

am trying to darken the finish

Since this is your end goal a headsup is in order.

Bamboo is typically slightly denser and harder than sugar maple/hard maple and just like maple it does not typically stain well (staining conventionally) because the high density makes it resistant to stain penetration.

As a result a coloured overcoat, such as "gel stain" (despite its name these are jellied varnishes) may be preferable to give you the result you want.

An added advantage to using such a product is the original finish does not need to come off first. As long as the existing surface is clean and matt subsequent finishes should bond to it acceptably well. See Good methods for scuffing/sanding ready-built furniture with contours for repainting for a little more detail.

1 For the record, I'm dubious.

2 And it still didn't remove all of it!

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  • Despite the possibility of not having had to remove the existing finish before starting on this adventure, I would think that now that some of it has been sanded off, the rest will have to be removed to make a future refinish (of any type) look decent. I can't imagine anything short of paint will give an even finish across the sanded corner and the unsanded, unstripped remainder of the surface.
    – FreeMan
    Commented Sep 23, 2022 at 15:29
  • @FreeMan, I thought so too until I noticed something I'd failed to when I skimmed it the first time: OP started on the underside....
    – Graphus
    Commented Sep 23, 2022 at 17:09
  • So long as the bottom isn't obviously visible. ;)
    – FreeMan
    Commented Sep 23, 2022 at 17:15
  • Yes, I started on the underside to test my plan first. :-) Interesting tip about the gel stain (which I happen to already have) not requiring the original finish being removed first.
    – Chris Morris
    Commented Sep 23, 2022 at 22:19
  • @ChrisMorris, although I rag on "gel stain" a lot that's for its stupid name :-D and actually it's a great product to have at our disposal, with a few cornerstone uses including working over existing finish. Also can be the product of choice for colouring dense hardwoods and blotch-prone woods (esp. softwoods).
    – Graphus
    Commented Sep 24, 2022 at 5:29

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