Painting over varnished ply

[mark99]

On 16/09/2020 at 12:28, Higgs said:

 

I was with you all the way until -  " Obvs afterwards then some proper Alkyd enamel. Will be power sanding the scumble.... but it is ougside (covered wetdock)."

 

?

I won't using Zinnser after reading fully its limitations. It may break up and crack re external use! (Does not like expansion or contraction).

[MrsM]

There are quite a few different Zinssers and they are pretty good. Have used extensively during property restorations but not on a boat so interested to hear how people get on. 

[WotEver]

14 minutes ago, mark99 said:

I won't using Zinnser after reading fully its limitations. It may break up and crack re external use! (Does not like expansion or contraction).

Where did you read that Mark? It’s specced for exterior use and I’ve never had it fail in my (admittedly limited) experience. 

[mark99]

I read the comnents in I think Screwfix (can't be sure) website which has loads of faq linked to Zinnser supplier who faithfully answered lots and lots of user questions. It's recomnended by Zinnser for spot priming external only (as in  bleeding wood knots etc - Zinnser Bin). Something about being shellac based and not liking expansion. I've used it at home in a house and its great.

Edited September 17, 2020 by mark99

[WotEver]

47 minutes ago, mark99 said:

I read the comnents in I think Screwfix (can't be sure) website which has loads of faq linked to Zinnser supplier who faithfully answered lots and lots of user questions. It's recomnended by Zinnser for spot priming external only (as in  bleeding wood knots etc - Zinnser Bin). Something about being shellac based and not liking expansion. I've used it at home in a house and its great.

Ah yes, Bin is only for spot priming. My recommendation was for Zinser Coverstain, not Bin. Coverstain is designed for internal and external use and is a full-function primer. Bin is more for covering knots in pine and such like. 

[mark99]

10 hours ago, WotEver said:

Ah yes, Bin is only for spot priming. My recommendation was for Zinser Coverstain, not Bin. Coverstain is designed for internal and external use and is a full-function primer. Bin is more for covering knots in pine and such like. 

Thank you. I recall trying to cover a waterstain on ceiling........ I must have recoated 12 times with emulsion until I discovered Zinnser/shellac.

 

 

Edited September 18, 2020 by mark99

[Movin' on]

On 16/09/2020 at 12:30, Rick Savery said:

Yes it would! so would someone else doing it for me! Sadly, neither of these are an option ?

 

The best way to take "ownership"of your new boat is to invest some sweat into it!?

[LadyG]

I got great results with Zinsser perma white ( lots of colours) , I used Teamac primer for one area, which was heavily varnished and no primer elsewhere, really good covering, unlike B&Q, stuff. Rawlins paints of Leeds.

[RickS]

1 hour ago, Halsey said:

 

The best way to take "ownership"of your new boat is to invest some sweat into it!?

Having taken a mattress, a sofa and a lot of carpet out of the boat, and a cooker onto the boat, I can confirm I have sweated copiously! But I do take your point, and agree with you ?

[RickS]

Steph H and KenK - thankyou for your thoughts on this also. I have now bought some Zinsser 1.2.3 as a primer. i will probably go with some sort of emulsion finish.

 

I hear what you are saying Steph H but do worry about possible messy painting and cleaning up after oil-based paint - that may change when I get the emulsion on ?

 

Edited September 18, 2020 by Rick Savery

[LadyG]

4 hours ago, Rick Savery said:

Steph H and KenK - thankyou for your thoughts on this also. I have now bought some Zinsser 1.2.3 as a primer. i will probably go with some sort of emulsion finish.

 

I hear what you are saying Steph H but do worry about possible messy painting and cleaning up after oil-based paint - that may change when I get the emulsion on ?

 

BandQ , crown etc is useless on a boat, use zinsser permawhite, that is a brand, not a colour.....

I have somescrubable white with 7year guarantee, the standard bandq and crown needed overcoating several times, eight coats to cover blue gloss!

Edited September 18, 2020 by LadyG

[RickS]

Thanks LadyG - not sure I understand. Why is B & Q (ie bog standard) emulsion (I assume emulsion) no good on a boat please?

 

I will look at Zinsser Permawhite, but if I have primed with Zinsser 123, will a standard emulsion still need lots of coats?

Edited September 18, 2020 by Rick Savery

[WotEver]

1 hour ago, Rick Savery said:

if I have primed with Zinsser 123, will a standard emulsion still need lots of coats?

It depends on the paint. Some has lots of pigment and covers well (I’m a fan of Leyland for that), and some goes on like dirty water (I bought some like that from Wilko once). 

[LadyG]

15 hours ago, Rick Savery said:

Thanks LadyG - not sure I understand. Why is B & Q (ie bog standard) emulsion (I assume emulsion) no good on a boat please?

 

I will look at Zinsser Permawhite, but if I have primed with Zinsser 123, will a standard emulsion still need lots of coats?

You get what you pay for, the paint components include pigments, less pigment per litre mean you have to use several coats to get good coverage. The more expensive paints have more pigment.

On a boat the surfaces are subject to flexing, due to heat expanding the steel shell and the wood interior not expanding in sympathy.

The surfaces inside and outside a boat are subject to considerable wear and tear, constant scrubbing to remove grease, soot and grime, so I use a commercial type paint, such as would be recommended for commercial use. I think one is scrubable, ie for use in catering, and has a seven year gaurantee in light to moderate use.

I bought a tin 750ml from BandQ, to paint a bathroom door and two small wall panels, the door is Ok, the other panels bleed , ie the pigment does not cover the previous coat, and that is with two or three coats, 

I am refurbishing my boat which was previously painted by application of gloss straight on to ply, or varnish straight on to ply, very rough, tough and difficult to redeem, Interior surfaces get grease and soot from stove and cooking, sugar soap is a minimal requirement.

The best result was flattening the varnished ply with glasspaper, then zinsser primer then zinsser topcoat, the worse result was overpainting gloss, which was prepped with sugar soap and wet and dry then B and Q quck dry acryllic, even three coats of white does not cover the mid blue gloss.

I now buy all my paints via Rawlins Paints, who are not (as I was  told by technical), a decorators merchant, lol.

My boat is 57 foot cc liveaboard, and I am refurbishing all surfaces, I never want to do the whole thing again! The first year I had to re paint the ceiling twice, that was after using two standard Crown undercoats and one topcoat.

I am using Rusto,eum Combi color for outer surfaces, the hull above waterline to gunwales takes 2.5l per coat, it is a flexible paint so is ideal for the hull, above waterline, £40for 2.5l black.

Edited September 19, 2020 by LadyG

[Ronaldo47]

In the 1970's I used to know a chemist who worked for one of the major paint companies. He told me that DIY own brand paints, especially white emulsion, were made down to a price, not up to a performance. The DIY chain would tell them how much they were prepared to pay wholesale for a 2.5 litre tin, and the manufacturer would  use ingredients to match that price. Thus the quality of such paints could, and usually did,  vary from year to year as the  costs of raw materials fluctuated. He said that, to ensure consistent performance it was best to use trade paints that were made to a technical specification rather than a price. Before lead paints were banned, I used to use "Magnet" traditional paints that were made to a British Standard specification and had a stated design life of at least 20 years, which has turned out to be correct.

 

I now use Dulux Trade oil-based paints for exterior work. Their oil-based trade undercoat has really excellent covering power, and Dulux do say it is better in this respect than their non-trade product. When we had an extension built a couple of years ago, we retained the original back door as an internal door. The old exterior door surface was painted black, so I had expected it would need two coats of undercoat. However, it only needed one coat of white undercoat to completely obliterate the black gloss in readyness for the white top coat. Nothing like as durable as lead paint on external woodwork though. 

 

When applying oil-based paint, it is best to use traditional bristle brushes to avoid brush marks. Most of the brushes in the shops now have synthetic bristles  I did try them, but found that they did leave prominent brush marks, so reverted to my real bristle brushes.  

Edited September 24, 2020 by Ronaldo47
Typos

[RickS]

That's interesting, thanks Ronaldo47. I am changing my view of paint - from what people are saying, you kind of get what you pay for - so I won't be using the cheap paints I was first looking at.

 

Dulux Trade Weathershield / Metalshield has been suggested for external painting of the boat, but that is for another day.

 

I still don't think I will be using oil-based paint as the topcoat, but I supsect your advice about real bristles probably holds true for all paint - thanks again

[Ronaldo47]

While I do have some new brushes, I am still using some bought at least 20 years ago.  Even expensive brushes tend to shed some bristles when new, so I always use my old brushes for finishing coats. I have two old 1 litre paint tins containing white spirit, let's call them A and B. Immediately after finishing painting, I get as much paint out of the brush as I can by brushing out on a piece of scrap wood or cardboard,  wash out as much paint as possible in tin A,  wash again in tin B, and finish off with washing up liquid and water. After leaving to stand, the white spirit in both tins usually eventually clears as the paint particles settle out. When tin A gets too full of paint sediment to leave enough liquid space to immerse the bristles, it is thrown away, tin B becomes tin A,  and a fresh empty tin becomes tin B.  More environmentally-friendly than using fresh white spirit or a chemical brush cleaner and dumping it after a single use.  

 

 

Edited September 24, 2020 by Ronaldo47
Typos, clarification