What's the best primer for exposed woodwork?

This must be a common problem. I searched, but couldn't find it having been asked before.
We seem to have a significant problem with topcoat, undercoat and primer all peeling off in one go, so I'm assuming it's the primer that's failing. This happens on everything from vertical wagon sides to horizontal running boards.
We've been using basic cheap acrylic primer at around £12 for 2.5 litres. Is this the problem?
Is the £45 for 2.5 litres stuff worth the extra?
I believe it is still possible to get lead primer. As we are unlikely to get children chewing our wagons, would this be worth looking into?
What are other people using?

 

It may be old-fashioned of me, but I'm still distrustful of water based paints for things like that. I much prefer an oil/solvent based wood primer. For years our supplier Williamson's has sold Mastercraft wood primer, but since they've been taken over by Thomas Howse they seemed to have switched to Crown, which is also solvent based. We haven't been using it long enough to find out how good it is yet! So far all we've noticed is it takes longer to dry than Mastercraft.

 

By far the very best primer for exterior timber is "Timberseal PS". It comes from the wooden boat industry.

https://www.boatpaint.co.uk/cgi-bin/sh000005.pl?WD=timberseal&PN=Reactive-Resins-Timberseal-PS.html#SID=894?a39395

Basically its a very thin 2 pack epoxy which sets but when set is still slightly flexible. It can even be painted onto semi-rotten timber and still holds paint for years when all the paint around it is flaking off. Downside is that being a 2 pack epoxy painting time is limited before it starts to go off, and brushes have to be cheap and disposable.

H&S restrictions apply regarding ventilation etc so read the instructions/MSDSheet.

You don't have to believe me, give it a try on your most troublesome wagon and see how well it survives.

Andy.

EDIT - I have found that a single coat is enough, and that once dry it can be painted over using any conventional undercoats and gloss.

 

How strict is the overcoat time on that Timberseal PS? Minimum 8 hours to maximum 4 days may be difficult to achieve in the winter when I'm only there one day a week.

 

Leyland also do an oil based wood primer https://www.smithandallan.com/products/decorative-paint/4616-leyland-wood-primer-white/

 

As I understand it from Williamson’s, they haven’t been taken over by Thomas Howse but the reverse. However, as the paint mixing equipment at Howse was better than at Williamson’s the factory at Ripon was shut down and it is now simply a distribution depot and sales counter.

 

Oh! That's interesting. We (belatedly) got sent a letter with the following earlier this year:

Dear Customer,
I am pleased to announce that as from the 1st of January 2021 we will have successfully merged our business with our sister company Thomas Howse Ltd, also owned by the UK Coatings Group Ltd.
We will continue to operate the T & R Williamson brands and the site in Ripon but all administrative and accounts functions will be consolidated at the head office in Rowley Regis. I am confident you will receive even more support and cooperation from all of our sites, the new laboratories and the benefits of our extended product range which now includes powder coatings. I am sure we can continue to work together to develop and grow the business with all the benefits the merger brings. T & R Williamson will henceforth be an operational unit within Thomas Howse Ltd and as a result of the merger some of our contact details will be changing.

 

I use this stuff all the time for priming wood and metal, painted a whole coach with it, soaks into the wood.

https://www.johnstonestrade.com/product/quick-dry-zinc-phosphate-primer

Wonderful paint, covers everything in just one coat, starts drying in about 1 hour without any brush marks. You can get it in 2.5 or 5 litre tins. I have always used the red oxide, but they do it in grey and white too but not tried those. You can get it in Johnstones decorating centres. (Ask for a discount) Use Cellulose thinners to clean your brushes and stop them going hard. Other paint goes on top of it without any issue.

The two ones you have quoted are both water based paint, wouldn't use anything water based unless it's say the interior of your house.

 

Owatrol oil: https://www.owatroldirect.co.uk/product/owatrol-oil/

It's single pack, soaks into timber (or rust) like nothing else and sticks like you-know-what to the proverbial blanket. It does take a while to dry, especially at lower temperatures, but won't let you down.

It's not cheap but we've been using it on professional boat repaints for years and it has never let us down. If you want to two-pack on top of it they do a different, red tinted version: https://www.owatroldirect.co.uk/product/cip-corrosive-inhibiting-primer/

 

For bare timber, Sadolin Superdec. Two coat system, 10 year guarantee, As a decorator I use it locally on exposed timbers along the harbourside in Weymouth. It is also, I believe, used on sailing boats as well.

 

Thanks, that's six recommendations so far, and each one different. The one thing everyone seems to agree on though is that conventional water based primers are not the best, so we'll definitely move away from those.

 

Graham. In the C&W both at Kidder and Bewdley. We use aluminium wood primer and have never had a major issue with it.

 

On thing to bear in mind with paint, is don't get it from somewhere like B and Q. For example with the Johnstones paint, they have two basic products lines, retail paint which for them has a blue logo and trade paint which they sell in decorating centres and which has the red logo.

The retail stuff they told me themselves is very thinned down and will never coat as well, it is designed to make it cheap alongside other competing brands for diy customers who want something cheap. (ie in B and Q etc)
The trade paint at the decorating centres is thicker and is designed for painters who want the better quality so they can get in and do the job in two coats max, but obviously it costs more but that is what you want.

 

Southernman, I'm sure I've heard the other guys in the Wagon Department say they've used aluminium primer in the past and it was no better than acrylic, although reading toplight's reply, that may be down to the source of the paint, not the type of paint.

toplight, that's not something I'd thought of.

 

We use Williamsons ali wood primer. I recently removed panels from 1086 that were done in the 80s during restoration. The varnish and scumbling had become damaged but the primer was still in good condition.
The other issue is the timber swelling and contracting which will slowly push the paint off the timber.

 

Isn't that internal wood though? Apart from the brake van interiors, everything we paint in the Wagon Department is left outside in all weathers.

 

We had the same problem and moved to using ali primer on the benches at Bridgnorth (pre-2017). It made no appreciable difference. You could ask the station teams what they're using?

Patrick

 

Have you thought about contacting other wagon depts on other railways?

Ali primer requires 2 coats for exterior use. If I see Steve P or Hollis. I would ask what timber you're using. Any resinous timber needs 2 good coats of primer or a WRP, Water repellant preserver as this seals the timber. The other option is sanding sealer which I use in furniture making before applying finish to items.

The wagons and some coaches will sadly be forever in a Forth bridge cycle. They only look good once, then we put them into traffic.

 

Not me, Superdec is water based and very flexible.

 

I and many colleagues at the Bluebell have used ali primer for years with no apparent problems. I've recently been introduced to the 2-pack epoxy primer, which is said to be very good for sealing end-grain. For any particularly demanding application, Zinsesser Bullseye 123 is a handy but expensive sealer-primer to have up your sleeve. It's the ultimate for me.
Richard