Etching

**Sunnybank** · 17-08-2009, 07:35 AM

Originally Posted by Coco

What kind of acid do you use to etch?

Nitric acid

**Coco** · 17-08-2009, 08:49 AM

Can you get it from Cooksons? I had a look and couldn't see any, I was probably having one of my moments though

**ps_bond** · 17-08-2009, 08:59 AM

The stopping out varnish from Cooksons is Mylands black polish - a shellac-based furniture polish from http://www.myland.co.uk/shellac.html
The advantage of having black is so you can see where it is

I've never tried marker pen with nitric; it works well in ferric chloride however. Surface prep always seemed to be key (no pun intended!) to getting the permanent marker to stick; I tended to use Sharpies because they were on hand. Nail varnish works. Asphaltum is the "classic", but it is revolting to work with. I think O'Keefe advocates paper strips for an etch resist for some bits...?

If you're going to do photoetching, you need to experiment to see how light-proof your printer is. I've a preference for laser printers for doing this - they give a completely opaque black, whereas some inkjets aren't quite as effective. Maplin used to sell photoresist, I can't seem to find it on their site right now.

Oh, and nitric acid is a PITA to get hold of - EU regs on couriering again, AFAIR. Ferric nitrate is more readily available - and a bit safer.

**Coco** · 17-08-2009, 10:13 AM

How is photo etching different from regular etching?

**ps_bond** · 17-08-2009, 11:49 AM

You use a photographic process to set up the etch mask, rather than a manual drawn technique. Expose and develop the image on the substrate, then etch it.

**Sunnybank** · 17-08-2009, 12:30 PM

Thanks Peter for your help.

I bought the nitric acid in Cousins then had to dash for the train so I didn't have time to go round the corner to Cooksons for the Black Polish. I thought it would be easy to get from a DIY shop, but I can only get white polish, which as you say would be hard to see. I've got plain shellac so I may try that on a piece of scrap, my scrap pot is emptying rapidly.

No plans so far for photo etching!

**ps_bond** · 17-08-2009, 03:33 PM

Originally Posted by Sunnybank

I bought the nitric acid in Cousins then had to dash for the train...

I think you'll find the rail networks are not particularly pleased by people taking conc. acids on their trains...

(They get stroppy enough about compressed air cylinders!)

**Solunar Silver Studio** · 17-08-2009, 04:06 PM

Can't you 'tint' your polish or shellac with something....Water based/oil based/solvent based (delete as required!)... so that you can see where you are putting it??

**Lindyloo** · 17-08-2009, 08:57 PM

Peter, can you be specific about which Sharpie pen is the right one. I just looked them up and they come in a variety of different types. Is it the enamel pen for example, or just one labelled permanent marker?

Linda

**Sunnybank** · 17-08-2009, 09:20 PM

[QUOTE=ps_bond;4679]I think you'll find the rail networks are not particularly pleased by people taking conc. acids on their trains...

I'm sure the plastic carrier bag was COSHH compliant!

Can't you 'tint' your polish or shellac with something....Water based/oil based/solvent based (delete as required!)... so that you can see where you are putting it??

I did wonder about doing this, Barbara, I'll give it a try now someone else thinks it might work.

Thanks both, I'll let you know how I get on.