Classic cars forum & vehicle restoration.

Rootes75 · Posted: Wed Aug 19, 2015 9:52 am Post subject: Sealer

Question.

I have read a lot of people simply spray primer straight on over filler/old paint etc but recently a few books I have looked in recommend using a 'sealer' coat first before applying primer.

I will be using Cellulose for primer and top coats.

The professionals seem to say one thing and the home restorers another. Many of our friends simply spray straight on out in the open also not using tack cloths etc.
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MikeEdwards · Joined: 25 May 2011 Posts: 2470 Location: South Cheshire

I think this is another issue where the more you research, the more conflicting advice you get. I'm looking at paint for mine, fortunately sealer isn't something I've had to worry about as I've taken it back to bare metal. The issue is if the new paint you put on causes a reaction with existing paint layers - I guess it depends on how much you know about the existing paint.

Rootes75 · Posted: Wed Aug 19, 2015 11:56 am Post subject:

You're right, there is a lot of conflicting information. A lot of books are aimed at someone wanting or aiming to get a concours finish. I am spraying a lorry that I want to look good but if there are blemishes it won't look too out of place.
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Various Rootes Vehicles.

peppiB · Posted: Wed Aug 19, 2015 12:30 pm Post subject:

Depends what the existing paint is. Cellulose will not cover 2K without a reaction (although 2K will cover cellulose) The commonly used barrier coating is like thick 'pink medicine' and gives off really obnoxious fumes, but it does prevent differing paints reacting with each other

Rootes75 · Posted: Wed Aug 19, 2015 1:48 pm Post subject:

The paint that is still on the cab is a thin rubbed down layer of Johnsons Red Oxide.
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Various Rootes Vehicles.

Phil - Nottingham · Joined: 01 Jan 2008 Posts: 1252 Location: Nottingham

I have always used Barcoat which is waterbased and dries very fast. A very thin coat is all that is required
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ajlelectronics · Joined: 04 Oct 2010 Posts: 168 Location: Gloucester

The very best method is to use epoxy primer. That will not react and does not behave hydroscopically, unlike conventional types. No Isocyanates, so safe to spray.
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ukdave2002 · Joined: 23 Nov 2007 Posts: 4104 Location: South Cheshire

If the top coat is not going to applied to the primer within a few hours of priming, then I agree Epoxy is the way to go Smile

Many a respray has been spoiled weeks / months later when the moisture that primer has absorbed ( and it can only take hours) reappears as micro blisters in the top coat Sad

Exposed filler will also absorb moisture, if you can get back to bare metal where filiter has previously been applied it's worth it.

Dave

Rootes75 · Posted: Thu Aug 20, 2015 10:55 pm Post subject:

So, is it ok to use epoxy primer then cellulose for the top coats?
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Various Rootes Vehicles.

MikeEdwards · Joined: 25 May 2011 Posts: 2470 Location: South Cheshire

I hope so, that's what I'm doing. Although to be fair, it's not quite cellulose, it's a modern equivalent 1-pack paint in my case.

ukdave2002 · Joined: 23 Nov 2007 Posts: 4104 Location: South Cheshire