Streaky paint

[Craig1]

Hi all

 

Another paint question I'm afraid.......I've just had my boat in a polytunnel for a week.  I put two coats of craftmaster high build undercoat on, then two coats of the craftmaster coach enamel in graphite grey.  I thinned it with owatrol.  It was applied with a mini roller then laid off with a brush.  The undercoat went in fine but topcoat came out streaky all over as you can see from the photos.  It wasn't caused by the laying off, it was like the pigment separated all the time.  I stirred that paint plenty with that drill stirrer thing and kept stirring all the time to no avail.

 

So, I'll be putting a third and hopefully final coat on at some point this summer.  How do I avoid this happening again? Was it the heat in the poly tunnel? Is it a problem with the paint, or have I simply offended the Gods?

 

I know some of you guys know your paint, what do you reckon?

 

Cheers for any help,

 

Craig

 

 

 

[Slow and Steady]

I would love to know the answer. I did exactly the same as your process but outdoors in the shade with International Toplac paint. Got to be the laying off? 

No problem getting it shiny, my camera took a lot of confusing to stop it focussing on the reflection of next door's boat/the pontoon.

Edited June 1, 2022 by Slow and Steady

[Slim]

I would suggest  that you didn't lay it off correctly or that you didn't  run one roller load into the previous one. You can see distintly the individual  roller tracks. Best I can describe it.

[Tracy D'arth]

I roll paint on randomly, diagonally, and lay off vertically, is that not the way you do it?

[Slow and Steady]

12 minutes ago, Slim said:

I would suggest  that you didn't lay it off correctly or that you didn't  run one roller load into the previous one. You can see distintly the individual  roller tracks. Best I can describe it.

You can't see the roller tracks on mine, I went in all directions, overlapping previous and son laid it off. I'm sure it's the laying off. Can't speak for Craig.

8 minutes ago, Tracy D'arth said:

I roll paint on randomly, diagonally, and lay off vertically, is that not the way you do it?

Yes! About 18" at a time, totally random directions, the stripes are much narrower. Funny thing is it only happened in this session, the other half of this side done on a different day, same people doing the same thing with the same paint - no stripes.

 

Pics were taken soon after - the brush marks all but flattened out over the next week or three as it dried properly.

Edited June 1, 2022 by Slow and Steady

[LadyG]

I concentrate on keeping things in four inch squares, in my mind, so that would extend to four by eight, eight by eight and so on.

I don't add anything to the paint.

The best foam rollers, and a good brush, not too big, not too small, keep everything clean.

I assume you can't use any sort of sanding, and you would have to wait two weeks for it to cure.

I think you should phone Craftmaster and ask for advice.

 

Edited June 1, 2022 by LadyG

[Slow and Steady]

9 minutes ago, LadyG said:

I think you should phone Craftmaster and ask for advice.

I phoned International who were very helpful but had no advice to offer and claimed they'd never seen it before. I sent them photos.

4" squares? Blimey.

Roof was fine - same process and materials, different colour. I don't think we're too bad at this malarky. We go like the clappers to keep the wet edge, probably did 50ft of roof in under 2 hours I wasn't timing it. It might have been as little as an hour.

 

Edited June 1, 2022 by Slow and Steady

[Slow and Steady]

We could see the stripes immediately and tried all kinds of rollering technique in case the paint wasn't being spread evenly. At first I was going up down them spreading so we tried putting on horizontally and spreading, then diagonally, then totally random mixture but it made no difference. Obviously also considered the laying off side to side pressure might also be the cause or overlapping the laying off. It was a very annoying day as we kind of felt we had to keep going!

Edited June 1, 2022 by Slow and Steady

[LadyG]

I don't actually only do four inch squares, I visualise where they would be and sort of work from there, so my first roll would be eight horizontal, then eight vertical, then sort of fill in with another eight horizontal and so on, it ends up with a very even layer of paint, which can be laid off with a brush (this time I am doing it in four inch squares, but continuously , if that makes sense) when there is a reasonable rectangle which can be laid off, a lot depends on temperature of the paint,and ambient, I would not want cold paint or hot boat!

I try to keep going so paint is still same viscosity as I move along, that is to say I can start rolling again at the edges.

If the paint layer is fairly viscous, you need a light touch with the paintbrush. Modern paintbrushes may be designed for heavy loading, ie not for laying off, so make sure this is not the problem.

Edited June 1, 2022 by LadyG

[Alan de Enfield]

Was the temperature above Dew-Point ?

Was the steel 'warm' and dry ?

 

I had a similar problem when there was a very very thin coating of moisture on the previous coat. I wiped it off and tried again later in the day and it went on with no problems.

 

Just a thought !

[MtB]

52 minutes ago, Craig1 said:

I thinned it with owatrol.

 

Given the astonishing amount of time, trouble , knowledge and experience that Phil put into the formulation of Craftmaster paint, what makes you think you know better and decided to thin with Owatrol?

 

My bet is this was the problem.

 

 

 

[Slow and Steady]

2 minutes ago, Alan de Enfield said:

Was the temperature above Dew-Point ?

Was the steel 'warm' and dry ?

 

I had a similar problem when there was a very very thin coating of moisture on the previous coat. I wiped it off and tried again later in the day and it went on with no problems.

 

Just a thought !

Thanks for that - no it was high summer, the steel was warm but hadn't had the sun on it. It was definitely not damp and that was the 3rd coat of gloss - yep the other two underneath had no stripes! Damn, we wish we hadn't done that last coat! We were doing a coat every day to get the chemical bond. We would run a fine DA lightly over it to knock off any high spots, then tack rag the dust off so no white spirit or water used to clean it.

3 minutes ago, MtB said:

 

Given the astonishing amount of time, trouble , knowledge and experience that Phil put into the formulation of Craftmaster paint, what makes you think you know better and decided to thin with Owatrol?

 

My bet is this was the problem.

 

 

 

He also sells a similar paint additive plus all these paints can be thinned to a degree depending on conditions. So... you're off the track there I think.

https://www.craftmasterpaints.co.uk/products/additives/

 

[Barneyp]

Looking at the pictures I doubt it is related to the application (the rollering or the laying off) unless you only rollered using up and down vertical strokes that were all exactly parallel and didn't lay it off at all. 

 

Given the vertical lines it is possibly caused by moisture either when the undercoat or topcoat was applied, The higher gloss levels of topcoat can highlight defects in the undercoat.

 

Polytunnels aren't a great place for creating a good environment for painting, they protect from rain and other external contaminates, but the temperature varies and they trap moisture, and most people don't seem to take account of this.

 

Also thinning with a product from a different manufacturer is not a great idea, modern paints are manufactured to very tight and specific specifications, which have a lot of effort put into them, putting a "thinner" into them doesn't just make them more runny/less viscous it can alter the composition of the paint, possibly separating the pigment from the carrier.

 

 

[Slow and Steady]

27 minutes ago, Barneyp said:

Also thinning with a product from a different manufacturer is not a great idea, modern paints are manufactured to very tight and specific specifications, which have a lot of effort put into them, putting a "thinner" into them doesn't just make them more runny/less viscous it can alter the composition of the paint, possibly separating the pigment from the carrier.

Could be in my case - we might have overdone the white spirit on the last coat, but the previous 2 coats were fine with owatrol and some white spirit.

[RAP]

Do not use white spirits to thin the paint, this in itself can contribute to streaking. Too much Owatrol will also do the same - DAMHIK!

If using Craftmaster paints then you really should use their thinning agent, especially if you want to maintain a wet edge during application.

[Higgs]

Leave out the Owatrol, and don't thin too much. I don't know why people think Owatrol is a wonderful ingredient that imparts some magic. Owatrol is not necessary. Use a suitable thinning agent. Keep it simple. In a polly tunnel, temperatures can be high. Plan the time you're going to paint. At this time of year, temperatures shouldn't be that bad. 

 

In the years of painting narrowboats, never once used any additive but white spirits for oil based paint. I wouldn't have expected the paint agent to listen to me, if any problems happened with their paint, after using additives. As someone has already alluded to; paint manufacturers don't spend a fortune on the development of paint products to require more additives to improve them, when being used. 

 

Mini rollers are for mini jobs. Use a 7" roller. 

 

 

 

 

Edited June 2, 2022 by Higgs

[MtB]

9 hours ago, Slow and Steady said:

He also sells a similar paint additive plus all these paints can be thinned to a degree depending on conditions. So... you're off the track there I think.

https://www.craftmasterpaints.co.uk/products/additives/

 

 

But this is my point. How do you KNOW it is "similar"? Are you a paint chemist?

 

If you need to adjust the formulation of a paint, do it using products the manu recommends and ideally, makes themselves for the purpose. e.g. the additive you list that Phil designed and sells for the job. Then as Higgs points out, you are on more solid ground with a complaint to the manu. 

 

 

[Tonka]

11 minutes ago, Higgs said:

Leave out the Owatrol, and don't thin too much. I don't know why people think Owatrol is a wonderful ingredient that imparts some magic. Owatrol is not necessary. Use a suitable thinning agent. Keep it simple. In a polly tunnel, temperatures can be high. Plan the time you're going to paint. At this time of year, temperatures shouldn't be that bad. 

 

In the years of painting narrowboats, never once used any additive but white spirits for oil based paint. I wouldn't have expected the paint agent to listen to me, if any problems happened with their paint, after using additives. 

 

 

I/we do not use white spirit to wipe steel down before painting as it has an oily finish. We use panel wipe. So why put it in the paint. We would use PPA but only if we feel it needed depending on conditions of the day

[Higgs]

3 minutes ago, Tonka said:

I/we do not use white spirit to wipe steel down before painting as it has an oily finish. We use panel wipe. So why put it in the paint. We would use PPA but only if we feel it needed depending on conditions of the day

 

White spirit would not be used to wipe panels down. I wouldn't use any additives in the paint, bar the thinning agent. If the steel is too hot, wait, until it isn't. Likewise, the air. I used to break early in the day, when the sun was beating down, and go back at 8 or 9pm, to finish. 

 

 

[blackrose]

26 minutes ago, Tonka said:

I/we do not use white spirit to wipe steel down before painting as it has an oily finish. We use panel wipe. So why put it in the paint. We would use PPA but only if we feel it needed depending on conditions of the day

 

I've never found that white spirit leaves an oily finish, perhaps at a microscopic level? I considered using tack wipes once on someone's recommendation, but as soon as I opened one pack I found oil all over my hand so scrapped that idea.

 

After prepping the surface, before painting, I always spirit wipe with the thinners used in the paint I'm applying. So if I'm applying Jotamastic epoxy on bare steel I spirit wipe with Jotun thinners 17; if I'm applying a single part paint where the instructions say to thin/clean up with white spirit (or Thinners no. 1) I spirit wipe with white spirit. I've never had problem doing that. 

 

I obviously don't spirit wipe if I'm applying a second out third coat within the maximum overcoating time for adhesion, but if I've gone over that time and need to key the surface then I'll spirit wipe to clean off the dust.

 

I'm not saying it's the right way but it's what I do and it works fine for me. The only time spirit wiping isn't suitable in my opinion, is if the surface is particularly oily or greasy like in an engine room. In that case spirit wiping is just going to shift the grease around rather than removing it. 

Edited June 2, 2022 by blackrose

[Higgs]

Surface wipe the steel. Once the painting starts, there's no need to use surface wipe. The paint will get plenty of flatting throughout the process. Vacuum and tack rag. Tack rags are ok. Use like a duster, no heavy wiping. It all helps, if you have a vacuum attached to any sanders. 

 

 

Edited June 2, 2022 by Higgs

[Tonka]

10 minutes ago, Higgs said:

Surface wipe the steel. Once the painting starts, there's no need to use surface wipe. The paint will get plenty of flatting throughout the process. Vacuum and tack rag. Tack rags are ok. Use like a duster, no heavy wiping. It all helps, if you have a vacuum attached to any sanders. 

 

 

I find that there is a big difference if you use the better quality tackrags rather then the cheaper  ones 

[Higgs]

1 minute ago, Tonka said:

I find that there is a big difference if you use the better quality tackrags rather then the cheaper  ones 

 

It happens with rollers, too. The plastic support doesn't reach the end of the roller, especially with those mini rollers. Quality of the foam. Brushes with no spring in them. You name it. 

 

 

[jacko264]

Hi all

where I work we paint all buses by hand  there is a video on utube how one of our painters  paints them with a roller and brush

Les has been painting buses for 40 + years 

look up 

painting a eastyorkshire  bus with brush and roller 

Graham

[jacko264]

https://www.youtube.com/watch?v=BYijGhAt-Ec

Here is thelink

Graham