Another Painting Question

[denis M]

Hello all,

I have stripped down my aging Romulus to do a overhaul and re paint and have found that the cab and roof are Galvanized sheet steel.
I was wondering what others use for etching / priming. I have taken a quick look through Chris Vines book but could not see anything specific.

Also as a matter of interest, the cylinder end covers were sealed using Loctite flange sealer and after 16 years were still well sealed and easier to take apart than casket paper. I mention as I have praise the product in previous threads.

Thanks

Denis

[chris vine]

Hi Denis,

Yes you are quite right, I made no mention of priming zinc.

One of the etch primers I liked was Upol #8 Acid Etch. It usually comes in a spray can and I got mine at the local automotive paint stockist.

I have just looked at my datasheet and it should be fine on zinc. Here is the relevant paragraph:

ACID #8 can be applied to the following surfaces:-
• Bare steel.
• Aluminium.
• Galvanized and Zinc coated steels.
• Fully cured paint.
• Polyester bodyfillers and G.R.P.
Thoroughly clean and degrease surfaces with a
suitable spirit wipe or thinner. Abrade wet or dry with
280-320 abrasive. Re-clean, dry and degrease.

If you would like me to send you the pdf datasheet, send a pm and I will email it to you.

I think Baggo is using this material at the moment and he tells me that you can buy it in litre tins.

The other etch primer I used and liked was Trimite SAP3 (SAP2 is the less toxic version although not quite so good. Though no one can tell me how much not quite so good!)

I have just looked at my data sheets for SAP 3 and 2, and although it implies that they should be good for zinc, it does not say so explicitly. You (or I) could always ask them the question. Their number is 01895 251 234. another one is 01895 201 444. Ask for the technical help desk, I found some of the people were better than others...

If none of this works for you, then I suggest asking the automotive paint supplier what they sell for use on VW, Audi and Porsche cars as these have all been galvanised for about the last 10 or 15 years.

I will be interested to hear how you get on,
Regards
Chris.

[baggo]

Hi Denis,

As Chris mentions, I'm using the U-Pol Acid *8 after seeing it in his book. I've tried it on some Zintec (which is basically galvanised steel) test pieces and it seems to stick like the proverbial to a blanket. I'm actually using it on brass and steel for which it works very well. You can't scrape it off with a finger nail when it's properly dry. It seems to be able to stand 250°C without any trouble although it does go a bit brown!

Halfords sell it in 450ml spray cans at £10.99 and it's also available in 1 litre tins if you want to brush it on or use a spray gun (got mine off Ebay) I've found it needs thinning about 5 parts paint to 1 part etch primer thinners for my airbrush. You can use ordinary synthetic or cellulose thinners for cleaning up afterwards.

It goes on quite thickly from the spray can so you have to watch you don't overdo it although it thins out a lot when it dries. It dries to a very nice matt grey finish which is ideal for painting with the top coat.

John

[chris vine]

Just to pick up on something John said,

The Upol 8 is a really good primer, but it does go on rather thicker than the Trimite SAP3 and SAP2. These go on like water and as all the solvents evaporate out, the dry film is hardly there at all. Very useful for not covering up tiny details.

However for ease of use, I don't think I have found anything better than the Upol. I have tried several others and they are a very mixed bunch with some not sticking at all. The trouble is that all your work is built up on the primer so it is important to get something which really works.

Chris.

[denis M]

Chris and John,

Thanks for your replies, I have used the U-pol primer on Ally before and have now trundled down to Halfords to buy some. Do you rub it down with wet and dry before putting the top coat on ?.

I was thinking of using Phoenix Paints as the top coat but I have also used to good effect before a paint made for the agricultural market which I think is made by International Paints. It comes in various colours to match all the farming machinery etc. I have also on my Baldwin used a car engine enamel by SPEREX or I SIMONIZE as these do not need a primer.

Anyway thanks for your comments and also Chris for the PM.

Regards

Denis

[chris vine]

Hi Denis,

Data sheets sent.

Be careful of the car engine enamels which do not need a primer if you are painting onto brass. I do not know the two paints that you mention but brass is seriously funny stuff to stick paint to!

Good luck
Chris.

[denis M]

Chris,

Yes agree, I should have said I only use it on steel.

My mistake.

By the way I spoke to you last year at Harrogate and must have been one of the hundreds that asked how do you keep your loco so clean. I have to say Mr Sheen is brilliant.

Denis

[brozier]

Denis,

I'm using Halfords High Temp Engine enamel on top of U-Pol #8 primer and it seems to work pretty well. I painted my wheels before machining and the edge is nice and crisp with no tearing.

I speeded up curing of both primer and paint using a small domestic table top oven. Easy to pick up at car boot sales...

I'll be using the Satin Black and Red for frame and buffer beams. The Gloss Black is probably better for High temp parts like the smoke box as it flats down with heat.

Many thanks to baggo for suggesting these and sharing his high temp experiments and to Chris for an excellent book.

If you do use Precision Paints I would also recomend the latest version of "The finishing Touch" book which was written by the guy who founded Precision Paints.

Cheers
Bryan