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Good day

We use Jorgensen parallel clamps in our workshop for most glue ups. Ever since cleaning the clamps with a steel brush, we get blue staining in the form of speckles despite the clamps not touching the workpiece.

The clamps have been cleaned several times with various solvents and a paste wax has been applied to them.

When the clamps touch the workpiece the transfer of the blue stain is worse and most concentrated below the clamps indicating that it is coming from the steel of the clamp.

It seems as though the speckles around the clamps are created when wiping the glue squeeze out with a wet cloth, even when the cloth doesn’t touch the clamps which themselves are raised from the workpiece. The cloth itself is stained blue after wiping.

Both the staining on the workpiece and the cloth is only visible after a couple hours.

Any suggestions on how to avoid this?

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  • Hi, welcome to StackExchange. Can you indicate what research you did on this prior to asking the Question please? I know there's some stuff out there on iron stains from clamp bars, although I don't recall ever seeing anything on this specific issue! I suspect this will naturally diminish over time, but what have you tried to lessen the problem that didn't work? It's important to flesh out Qs with these sorts of details, so that potential respondents don't link to info you've already seen and/or suggest fixes that have already been tried and didn't work.
    – Graphus
    Commented Aug 18, 2023 at 6:37
  • Maybe I don't understand it properly, but it seems to me that the problem is metal dust/unspecified dirt falling off the clamps - so I would suggest cleaning the clamps (which may include dissasembling which is not super easy but it's doable). Then if you hold the clamp over a paper towel and bang it a bit and nothing falls on the towel, chances are nothing will fall on the wood either.. But as I've said, maybe I'm missing something.
    – Jan Spurny
    Commented Aug 18, 2023 at 11:59
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    If giving the clamps a good cleaning doesn't do it, consider that the dust/debris is coming from somewhere other than the clamps. I'd think that enough debris on the clamps to "fall off" like that would be clearly visible on them before putting them to use.
    – gnicko
    Commented Aug 18, 2023 at 15:08
  • @Graphus Thank-you for the advice. I have edited my post.
    – Gina
    Commented Aug 19, 2023 at 3:53
  • @JanSpurny Thank-you for the feedback. Perhaps disassembling the clamps will prove successful if there is dust residue from the steel brush in the mechanism itself. I haven’t paid attention but if the staining is more concentrated on the side of the mechanism that could be the case.
    – Gina
    Commented Aug 19, 2023 at 3:53

1 Answer 1

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The clamps have been cleaned several times with various solvents and a paste wax has been applied to them.

This is exactly what I was going to advise unfortunately, so I'm bummed it didn't resolve the issue.

Any suggestions on how to avoid this?

If this was just on panel glue-ups I wouldn't be overly concerned about this level of iron staining in most present-day workshops environments due to the amount of post-processing these go through.

But obviously there are many other glue-up situations, and prevention is better than cure, so test all of the following one at a time:

Change the water used
It's quite common for domestic water supplies to contain some amount of dissolved iron. Try once with distilled water. If this still occurs you rule out the water being the source.

Use different wiping cloths
I suggest once using paper towels instead and if it still occurs it should rule out the cloths (shop rags?) being the culprit.

If you are using shop rags and they are contaminated with tiny amounts of iron just a fresh box might resolve the issue. Testing the cloths separately, nowhere near these clamps, seems like it would be a good use of time as well.

Test the glue
Again, do this nowhere near the clamps. Test a thin smear of glue on a scrap of oak. It's unlikely but conceivably possible that the glue itself is contaminated with iron. If it turns out this is the cause, contact Franklin directly or through the Titebond site.

If each of these doesn't work I think it conclusively proves the clamps are the source of the problem.

I just checked my most-used clamps of similar construction, which all have chrome-plated bars. When I wipe mine down, vigorously, with a paper towel virtually no grey/black is transferred to the paper.

If you do this and you get significant black stains on the paper then it suggest that the wipe brushing might have exposed bare steel along the 'knurling' along the edge. (Although it's not clear to me from photos whether the Jorgensen clamps still have chrome-plated bars or if they're now bare steel.) In which case it might be time to consider buying new clamps :-(


Until the issue is resolved, an aid to removing the staining
It's only a stopgap but in case you're not currently aware, treating with concentrated oxalic acid solutions should remove the iron staining, greatly reducing the amount of sanding or scraping that is currently needed.

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  • Thank-you. I will conduct a more thorough experiment with your suggestions and report back with any useful results or solutions.
    – Gina
    Commented Aug 19, 2023 at 15:04

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