Need Help!- Engraving on metal with paste

[Lazgrav]

Hello, everyone - my first post here

I have problems with engraving on metal with paste. We are trying to get big order and now produce tests. Engraving is on wood working tools, made from Chrome-Vanadium Steel. First of all we have tried Cermark, but results were very bad - see picture 1. The problem is "dirty clouds" after engraving.
After we have tried Litoscript. It works better but still SOMETIMES small "dirty clouds" appear. And it's happened suddenly, we can engrave 3-4 tools without problem, but on next engraving can see problems - see picture 2.

Surface was cleaned very carefully.
May be here is peoples famliar with Metal Physics or Chemistry who can explained process?

[Tweakie]

If you are spraying the Cermark then It may be a good idea to fit a better water / oil separator and filter to your air line.
Just a thought but those patches look very much like contamination.

Tweakie.

[Lazgrav]

We apply paste by brush as this is cheaper than spray. And quality with Cermark was bad, we have a lot of unnecessary marks. With Litoscript paste is better but still problem appeared.

[Lazgrav]

And this problem is happened only on this tools. When we engrave on any other metal - stainles steel or routing bits or souvenir flask - everything if fine.

[Rodney Gold]

Some metals get stianed by the paste - the best way to apply is to airbrush it on , thinly.
Basically , the way to stop it staining is to get it on , laser and get it off VERY quickly , if you leave the Cerdec/Whatever on for long times waiting for it to dry and not washing off immediately will make the metal stain more. Never seen those dark marks with Cerdec tho , seen the other type of staining before

[Lazgrav]

Thank's for advice. I am trying to clean metal as better as possible and will do tests later today. We try to maximum speed up process but result always the same
We use hairdryer to speed up drying - may be this is problem?

[Rodney Gold]

Well , it seems the metal reacts with the paste or something in the paste , almost like some stainless steel get water droplets that stain it. Cleaning the metal doesn't help much to avoid this. What we often do is cut a mask with some low tack paper based self adhesive and apply it , it leaves areas that are to be engraved cut out , then we apply the cerdec and engrave , it sort of limits the staining to only the marked areas and is not as noticeable.

[Lazgrav]

Problem solved
Shear surface was washed with Fairy, dried, cleaned with vodka just to be 100% sure that there is no grease on surface, dried for 15 minutes to be sure that all cleaning liquids evaporated
AND
engraving was perfect!!

There was some traces of what you, Rodney, named "stained" but really not visible too much. Now awaiting order from customer