Cermark making metal cloudy - Please help

[Jackie McGowan]

Hi all, If anyone can help it would be greatly appreciated. I'm doing heart bookmarks for wedding favors (wedding is next week). I don't know if they are chrome or steel. I have already coated them all (yikes). I tested one and the cermark made a slight mark (not black the way it should be) I know I can try slowing my speed for that (25 watt laser - 25 speed/ 100 power) My real problem is the cermark made cloudy brownish marks all over the pc. If there is a coating of some kind that interacted with the cermark is there anything I can get to take the coating & the cloudiness off? Or have I just ruined all 200 of these?
Please help

[Frank Corker]

It might be that your coating is too thick. It recommends that you only use the slightest amount and found that just enough to cover the stainless steel will do the trick. The speed is also dependent on the dpi. The power should always be 100% for all dpi settings. When the job is complete and ALL of the cermark is washed off, one drop of baby oil spread all over the item with your finger and wiped with a cloth is enough to put a nice shine back into it.

[James Stokes]

The only time I have had it leave marks when there was oil on the product. I now wipe every thing down with alcohol before spraying. Have not had a problem since.

[Joe Pelonio]

In addition to wiping with alcohol I'll always do a test first before coating the rest. If thermetal has a clearcoat on it that the alcohol won't remove, you have to rastor on lower power to remove the coating, then without moving the piece apply the cermark, then run again.

[Rodne Gold]

In general we have found all the metal marking pastes stain Stainless steel If you leave it on for any lenth of time you can see where it was. The only real way to stop this is to apply it properly. We thin the mixture with distilled water and add a few drops of dishwashing liquid (acts as a wetting agent and doesnt allow the stuff to bead)
I use a paasche gravity fed airgun (you cannot use the one with the bottle underneath) with a no 5 needle to spray apply. We built an enclosed pex box to do so as the overspray can be recovered. (our powder is also reusable so when the part is finished the excess is brushed off in this box as well). This gives an even thin layer which can be engraved at faster speeds with better definition and using this application method , we have seemed to eliminate the staining thing too , dries quicker tho we use heat guns to accelerate this. Brush and foam roller applications never work anywhere near as well as this.
We still take the precaution of coating pieces as close to them being lasered as possible.
Brown marks would tend to indicate the piece is silver or silver plated and you are getting formation of silver sulphide , a sort of tarnishing. I would try rubbing with silvo first.
If that doesnt work , try wiping with laquer thinners to remove any laquer coating (most plated parts are laquer dipped after to protect em) and then use silvo or brasso.
Silver , in our experience , does not mark well with a laser and cleaning in commercial jewellery cleaners (which have phosphoric acid in em) removes the mark as does frequent polishing with silvo or any other abraisive polish. Silver , brass and copper tend to tarnish and will all require cleaning at some stage , a process you can't control and potentially harmful to the mark.
ALWAYS tell the customer you need an extra piece for destructive testing or do a sample first on large runs of stuff you havent done before.
Even if you do that , life can be fraugtht with difficulty , we did a sample of a 14cm x 7cm mark on a stainless steel tray , cycle times were 2 mins 30 secs. When the trays were delivered (8000 of em) they were different from the sample in terms of metal composition and were dreadfully bowed , gouged and buckled at the engraving surface and to get a decent mark , cycle times would have gone to 8 mins or more. Yag had been tried but the mark was not black enough (had to be pitch black). The production qty was NOT at all the same as the sample and due to the difficulty of doing this job and the extended time required , we declined to go further. This caused a lot of problems for the customer (not our fault) but it also lost me a very lucrative job.