Prepping/cleaning CZ120 brass for epoxy resin paint.

[Wal WerbelParticipant @walwerbel59154]

Hello all.

I have a project on at the moment which involves having brass plates coated with resin – here's an example of one I made some time ago, the current project is the same kind of idea.

Before the resin stage I need to polish up the raised details which means that polishing compound packs in to the letterforms and creates a whole world of ball-ache to clean up. I've managed to refine the clean-up technique to something resembling 'tolerable' but I'm stuck for what to use for a final wipe down. In the past I've used fairy liquid, a toothbrush, numerous cocktail sticks, and then hot water to rinse – seems to work okay, but I'd like to know that I'm doing the job 'properly'.

Recently I read a self proclaimed de-facto explanation of how to prep brass for paint where the instruction was to use rubbing alcohol as a final wipe down. Okay, so surgical spirit (or isopropyl alcohol) then. But in many cases off the shelf stuff contains caster oil and will surely leave a residue and I'm not prepared to take that chance…

Am I over-complicating this? Once visually clean do I just paint in meths to all the nooks and crannies and then hot water rinse?

Many thanks.

Wal.

[Wal WerbelParticipant @walwerbel59154]

[duncan webster 1Participant @duncanwebster1]

Precision Paints caution against using Fairy Liquid, they claim it leaves a residue, meant to make your washing up gleam. Teepol might be better.

[BazParticipant @baz89810]

Certainly avoid any dishwashing liquid, it contains something to make the plates sparkle, the surgical spirit and acetone etc may well have additives, the best thing I have found is cellulose thinners, don’t use gun wash because it’s cheaper because it contains all sorts of things.

[Wal WerbelParticipant @walwerbel59154]

Yeah, I've had my doubts over the washing detergent, but when I ran my method by the customer service people at the resin company they said it was 'fine'… go figure.

I'm sure that the polishing compound is far from paint friendly too, which is why I seek the ultimate in degreasers for the final stage.!

Wal.

[Wal WerbelParticipant @walwerbel59154]

Posted by duncan webster on 26/03/2022 10:14:34:

Precision Paints caution against using Fairy Liquid, they claim it leaves a residue, meant to make your washing up gleam. Teepol might be better.

 

Duncan, why would Teepol be better? Would it not contain similar surfactants/additives? Genuinely interested as I'd buy myself a five litre bottle if it's an altogether better proposition than Fairy…

EDIT:  To be clear – detergent, whichever one I use, would not be the final stage of the cleaning process – I've just found it to be very effective at cleaning out the black deposits left by the polishing compound.  Once this is done, the brass would be rinsed and then 'properly' degreased.

Wal.

Edited By Wal Werbel on 26/03/2022 12:20:05

[Wal WerbelParticipant @walwerbel59154]

How about this?

My Dad had a bottle of this in his drinks cabinet back in the day. You can barely see that it's burning in the daytime. Ask me how I know.

Maybe a trip to the Sklep Polski is in order..?

EDIT: This stuff is never drunk neat – you add it into cake mix or use it in Nalewki (tinctures)…  Or MAMOD burners…  I did put some on my tongue once, which promptly shrivelled up.

Wal.

Edited By Wal Werbel on 26/03/2022 12:36:16

[SillyOldDufferModerator @sillyoldduffer]

Gorgeous brass plate in the photo, so the hard work method can't be far wrong!

I'd avoid Surgical Spirit for this purpose. Although mostly Ethanol and Methanol, a bunch of additives are added to make it undrinkable and improve its medical performance. Meths is cleaner than Surgical Spirit, but as pure Iso-propyl Alcohol is readily available I'd go for that.

Extreme cleaning is often multi-stage. I'd suggest:

1. Brush clean in hot water with detergent, followed by water rinse to remove the bulk. Or perhaps a pressure hose.
2. Ultra-sonic bath with detergent to get into the nooks and crannies, plus water rinse to remove the remainder of the polish abrasive
3. Rinse in Acetone to remove oily residues. (Unperfumed Nail Varnish remover might be clean enough.)
4. Rinse in IPA to finish off by removing Acetone residue and any additives left behind by the detergent.

Not all steps may be necessary. Much depends on what's in the polish and detergent.

Dave

[Merddyn’s DadParticipant @merddynsdad]

I would suggest something that contains a detergent and a fine pumice, that shouldn't affect your surface finish.

In the UK we have Cif, a cream cleanser which I have always found an effective cleaner prior to paint and resin applications, using a toothbrush or similar, it just rinses off in water, and generally shows a good 'water break test' surface.

The alcohol will only degrease, it won't clean out the nooks and crannies.

Washing up liquid contains lanolin, good for waterproofing sheep and for 'hands that do dishes', not so good for cleaning stuff.

Steve

[Wal WerbelParticipant @walwerbel59154]

Many thanks for your replies thus far.

Steve, being in the UK I'm familiar with CIF – I'm polishing to somewhere just shy of mirror so I fear that the abrasives in CIF might knock that shine off a bit – but hey – it might also make a good polishing compound… Got me thinking now… Had to look up the water break test (https://www.sciencedirect.com/topics/engineering/water-break-test) – nice tip.

[duncan webster 1Participant @duncanwebster1]

Posted by Wal Werbel on 26/03/2022 11:59:13:

 

Duncan, why would Teepol be better? Would it not contain similar surfactants/additives? Genuinely interested as I'd buy myself a five litre bottle if it's an altogether better proposition than Fairy…

 

That's a very good question. I had assumed perhaps naively, that as Teepol isn't marketed as washing up liquid it wouldn't have the 'gleam' additives, but who knows what else is in there? Data sheet is on line if anyone has enough chemical knowledge

Just dug out Precision Paints leaflet, they recommend PQ17 pre paint metal cleaner, but it's not cheap[,  data sheet here pq17

Edited By duncan webster on 26/03/2022 14:29:23

[Michael GilliganParticipant @michaelgilligan61133]

We have seen the difficulties caused by specifying “Loctite”

There is a similar problem with “Teepol”

Many, many, variations on the theme !!

Once upon a time, Teepol J was a pretty simple detergent, and the base of most domestic Washing-up liquids except Fairy. ..

Things have moved-on since then … try browsing through this lot.

**LINK** : http://teepol.co.uk/msds.html

MichaelG

[Wal WerbelParticipant @walwerbel59154]

So after further reading and taking into account advice given here and my own travails to date, I'm going to go with the following method:

1. Polish as usual
2. Use a detergent to clean off the polishing residues
3. Rinse
4. Use 99.7 pure isopropyl alcohol (RS do 500ml for about a tenner) to clean off detergent residues
5. Rinse, dry and buff

I just don't think there's a way of avoiding detergents and the related surfactants when it comes to cleaning up the black polishing residues that get into the tight areas of detail. The pure IPA should be the final word on clearing off the surfactants that are left behind by the detergent.

Even going with an ultrasonic cleaner you'd need to use a compatible solution/detergent to avoid pitting the metal, but that's perhaps a moot point – these plates are 320x240x6mm so would have to go out of house to get cleaned – sadly, if experience has taught me anything, then it's likely they'd come back super clean but covered in dents and scratches..!

Wal.

[pgk pgkParticipant @pgkpgk17461]

If/when Lidl have their cellulose thinner back on offer then probably worth grabbing some cans cheap – supposed to be residue free acetone.

pgk

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Wal Werbel on 26/03/2022 17:19:17:

.

1. Rinse
2. Use 99.7 pure isopropyl alcohol (RS do 500ml for about a tenner) to clean off detergent residues
3.  

.

Nothing against RS … they offer a great service

… but Hexeal is significantly cheaper : **LINK**

https://www.ebay.co.uk/itm/132712251077

MichaelG.

.

https://hexeal.co.uk/products/ipa?variant=52047399174

 

Edited By Michael Gilligan on 26/03/2022 20:16:17

[Robert Atkinson 2Participant @robertatkinson2]

Do not use sugical sprit. I's mostly methyl Salicylate. It also has castor oil in it.
For final cleaning I would use IPA or Methanol (more toxic) followed by a final wipe with acetone. Use a cotton cloth, synthetics can generate enough static to strat a fire.

For initial cleaning hot water with a few drops of cheap detergent (less additives) and some ammonia is excellent for brass.

[Grindstone CowboyParticipant @grindstonecowboy]

Can you still get ammonia? Not seen it on sale for years.

Rob

[the artfull-codgerParticipant @theartfull-codger]

I make cast alloy signs with fine detail & lettering on them & also cast brass nameplates & signs & I polish the details with 1200 wet & dry [wet] wrapped tightly on a rubber block,then I sandblast them with fine grit then polish again with w & d & polish with solvol autosol rubbed in to a cloth but wrapped tight round a rubber block so you don't polish the background I clean up with celly thinners & a paint brush & repeat three of times using fresh thinners then the final time I blow the [now clean] thinners off with the compressor blow gun & in my case I 2k etch prime before airbrushing with coach enamel 2 coats,sounds a faff on but I've never had a sign returned faulty. even years later.

Edited By the artfull-codger on 26/03/2022 23:51:08

Edited By the artfull-codger on 26/03/2022 23:54:04

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Grindstone Cowboy on 26/03/2022 21:46:15:

Can you still get ammonia? Not seen it on sale for years.

Rob

.

It would appear so : **LINK**

https://www.chemcentral.co.uk/ammonia-885-32-34-solution-177kg-drum.html

Smaller packs are widely available too

Try a Google search, with ‘Shopping’ selected.

MichaelG.

Edited By Michael Gilligan on 26/03/2022 23:58:35

[HopperParticipant @hopper]

Go to the paint section in your local car parts store and buy a bottle of Wax and Grease Remover paint prep liquid. No idea whats in it but its designed for exactly what you are doing: prepping metal surfaces for painting, including with epoxy 2 pack paint, and removing all traces of previous polishing and sanding residue. Purpose made for the job and not expensive.

[Alan CharlestonParticipant @alancharleston78882]

Hi,

I used to work in a chemical laboratory and we used to use a product called Decon 90 for cleaning glassware. It even removed silicone grease contamination which previously needed boiling chromic acid. It's still available:-

decon 90

The only problem is that it's alkaline so they don't recommend it for non-ferrous metals such as aluminium or zinc. I suspect brass should be OK but it may dull the highly polished surface. May be worth a go though.

The other thing is to invest in an ultrasonic cleaner which should get the solid contamination off with a minimum of brushing.

Regards,

Alan C.

[Wal WerbelParticipant @walwerbel59154]

Many thanks for the replies guys. Much appreciated.

Should finish the machining of this batch by the end of the week, then begins the abrading to soften the edges, then the polishing and cleaning. Some small spaces to get into..!

Wal.

[Martin King 2Participant @martinking2]

Wal,

Whatever you end up using I feel that you will not go far wrong using an ultrasonic cleaning bath; this ensure that EVERY nook and cranny is cleaned.

Cheers, Martin

[Andrew EntwistleParticipant @andrewentwistle]

Neutracon is the neutral version from decon that is fine for brass.

Andrew.

[Wal WerbelParticipant @walwerbel59154]

Just thought I'd post back with a bit more on how this has gone / is going.

Post polishing, the plaques look like this:

This is a rough vid describing the clean up stages (soap/rinse/alcohol/rinse):

From there the plaques go straight into new plastic bags and won't be touched again until they're up for paint.

Water lies evenly across the floor of the recessed areas after the alcohol has been rinsed off, so should be good.

Wal.

[Author]

Posts