[Closed] DIY: painting / eggshell question

I had the same problem and went for....

2 coats of Zinserr BIN, 2 coats Johnstones trade water based undercoat, 2 coats of Johnstones water based gloss. All prepped inbetween coats.

It took me two weeks but it'll be worth it in the long run.

Potentially and probably yes.

What does the manufacturer say. They will have put guidance on the tin or on a website somewhere. Much more use than a random forum 😉

Undercoating has a few functions

- it is a paint of a different type to protect what you are painting - e.g. an anti corrosive primer used on steel.
- it can provide a good bond - masonary/concrete where you put on a really thin penetrating coat first.
- it can protect the paint - wood coatings where they leech oil over time, most dramatically seen at knots.

If you've got existing paint on there then it is only really the bonding side that you need concern yourself with. Bonding is physical and chemical. The keying will provide the physical side. Just make sure it is free of dust and any obvious dirt.

Most household paints are single pack and don't rely on crosslinking reactions to dry. So the solvent used in the paint you have will likely dissolve it a little bit allowing for a good chemical bond.

As it is only decorative interior the performance requirements aren't that high so I can see it working. It is likely that the developer has tested it and found the adhesion is good enough.

I’m using trade paint - so hopefully good quality.

Dulux trade site says it doesn’t need undercoating.

Johnstone’s trade doesn’t say anything.

I’m using both brands (different colours...don’t ask 🤦🏻‍♂️)

It is paint specific. So Dulux will be ok if they say so as they will have done the testing. Johnstone's should say somewhere about how you use their product - what you should apply it over and how long it takes to dry. If there is no discussion of undercoat then it is likely you need one. To not need one is a selling point so would be talked about.

When they say self undercoating, it generally means you want need to undercoat first before the top coat, but you will need an additional top coat though... the first coat will act as a semi undercoat.

Back when I was decorating we always recommended Eggshell over Gloss due to the better coverage and more durable finish. We always used to undercoat first and that's the way to the best finish but you could probably get away with it. Depends how good a finish you're after.

Thanks everyone. I’ll prob undercoat, that’s what I’ve always done with Johnstone’s eggshell. I always do 2 x topcoats anyway.

I’m being paid to stay at home so may as well do a ‘proper’ job.

I’m being paid to stay at home

I’m decorating two hallways

Humblebrag or rulebreaker? 🙂

Can't offer any real help i'm afraid. I've just been doing our hall, stairs and landing and didn't undercoat...just keyed the existing paint and two coats of Leyland eggshell has left a pretty good finish on potentially 100yr+ wood.

Decorator here. Oil based eggshell (and generally satinwood) paints are self undercoating meaning that you use the paint itself as the undercoat and then again as a topcoat. Oil based gloss paint for woodwork will however require a specific undercoat before applying the gloss topcoat (probably on account of gloss not being a good enough key for a second coat to go on top of although this is just an educated guess.)

Have you sealed the knots with knotting compound?

I’m using trade paint – so hopefully good quality.

Isn't 'trade' in this context shorthand for 'cheaper than you'd spend on your own home'?

Isn’t ‘trade’ in this context shorthand for ‘cheaper than you’d spend on your own home’?

Generally not.

Trade paint is, in the main, designed to be of a quality that reduces labour time and leaves a job that you can charge actual money for.

If it wasn't then commercial decorators would just buy it in vast quantities from another, competing, manufacturer.

Retail paint is generally designed to sell more retail paint to someone who buys 3 tins a year.

Not my experience with Leyland white trade emulsion. But I buy about three tins of paint a year 😀

Not my experience with Leyland white trade emulsion

Try Dulux trade Diamond Emulsion. It'll change your life*

* Not really....but it is really good.

Noted, ta 🙂 !

I had the same problem and went for….

2 coats of Zinserr BIN, 2 coats Johnstones trade water based undercoat, 2 coats of Johnstones water based gloss. All prepped inbetween coats.

It took me two weeks but it’ll be worth it in the long run.

😲

I've just done my bare wood skirting. One coat of johnstones primer and one coat of Leyland trade satinwood. That's all I'm doing and finish is great. Never heard of two coats of undercoat before

 

Decorator here too. Usually I dont bother with U/C with eggshell just prep and spot prime filler/bare timber ect with U/C, then 2 coats of Eggshell/Satinwood.

Echo comments above. Most trade paints are better than retail stuff. Dulux trade is my preference.

Well I love that you all like Dulux 😉 not that it is my area.

I'd never apply two coats of undercoat either, unless there was an issue with coverage. In my experience of decorative paints then one coat is enough provided you get the coverage. It's only really where you expect the coating to do something that you might want to build thickness. But come from an industrial side of it everything is applied b thickness anyway.

I know there was a rumour that some trade paints are made thicker because decorators always seem to want to thin them back. In reality they work faster and have better technique so I guess they don't need as much help from the formulation to maintain a wet edge and get a nice glossy finish. They prioritise speed of application, drying and minimising the number of coats.

If you look at the trade ranges they are fairly simple as well. There are more retail branding options. For example you'll get kitchen and bathroom paints with different packaging retail as it helps sell it. Trade you just get "tough" for the more demanding areas.