Painting problem – bubbles

[gerry maddenParticipant @gerrymadden53711]

I’ve painted a lot of machine parts over the last few years using a brush and good quality machine paint from Paragon. I’m not the greatest of painters and never will be, but there is one issue that is annoying me for which I think there must be a simple solution.

After dipping the brush in the tin, as I make the first stroke the on the workpiece, HUNDREDS of tiny bubbles seem to be formed in the layer of paint which show no willingness to burst themselves. To eradicate them I have to repeatedly re-stroke the surface several times. By the time they have all been removed the paint layer is far too thin. When the paint is dry, I’m left with a coat that shows bristle lines and every imperfection on the original surface.

The bubbles are not in the tin of paint itself. They seem to be generated by the brushing action. For this reason I have experimented with many different brushes, from the cheapest to the best, and they all create these bubbles.

Paragons paints tend to be quite think so I have usually added some of Paragons “brushing additive”.  Apart from making the paint less viscous, I’m not sure what what this additive actually does. But could this be causing my bubble problem?  Or is there something else I’ve got wrong?  Any advice would be appreciated.

Gerry

 

[Grindstone CowboyParticipant @grindstonecowboy]

I find this usually happens if the brush is still wet from being cleaned – I don’t mean dripping wet, any trace of remaining thinners/cleaner causes it. I tend to use a couple of brushes in rotation so that they have plenty of time to dry off after cleaning.

Rob

[JasonBModerator @jasonb]

Are you going straight from dipping to the work surface?

Try pouring some paint into a paint kettle or other container then after dipping tap the brush against the sides of the container, this not only removes excess paint but also acts like that first touch on the work and can reduce bubbles.

A scabby old brush that has started to flair out does not help, make sure you use where the bristles come together at the end.

[Bo’sunParticipant @bosun58570]

Good morning Gerry.  I’d be inclined to ask Paragon, after all they’re the experts.

[Julie AnnParticipant @julieann]

I’ve had similar problems using coach enamel. It seems to be impossible to completely cure the problem. The bubbles are introduced by air getting trapped in the brush as the paint is applied. But there are some things that ameliorate the problem, for me at least.

• Use a quality brush with fine bristles; Purdy XL brushes are good but expensive. The Harris Revive brushes are just as good in my experience, and are available from B&Q at a sensible price.
• Load the brush with plenty of paint and ensure the bristles are full of paint, not air. There is a fine line between too much paint and not enough.
• Apply the paint with the brush at a shallow angle to the work and let the brush glide over the surface, don’t apply lots of pressure.
• I thin my coach enamel about 5% with the recommended thinners. It seems to help the paint to flow and level out.
• Make sure the paint is well mixed; I use a home made paint tin roller for an hour or so and then let the tin sit for an hour before painting.
• Don’t overwork the paint. I apply the paint, do one lay off pass and leave well alone. Very difficult to do as there will still be bubbles, but more strokes just make things worse.
• Some bubbles disappear quite quickly, tens of minutes, but others disappear over time, even over weeks and months.
• How you view the work makes a signifcant difference. Small bubbles are much more noticable under the harsh LED downlights in my kitchen (sorry, I meant paint shop) than in natural daylight.

Bubbles in the paint can be very discouraging. Believe me I’ve even considered giving up on my engines as there would be no point in finishing them if I can’t paint them properly. But hang on in there!

Julie

[gerry maddenParticipant @gerrymadden53711]

Thanks all for your thoughts and suggestions there. I now have plenty of food for thought and trials. If I can’t solve the problem after this there must be something wrong with me.

There didn’t seem to be any guidance of Paragon’s website covering my particular issue so I have sent their ‘help desk’ a message. I will let you know how I get on.

Gerry

[KEITH BEAUMONTParticipant @keithbeaumont45476]

When I have experienced similar bubbles in the first paint coat, I found “crossing off” (90 degrees to the original) gently, with a similar brush and angle, but this brush to be totally dry, eliminates the bubbles.

Keith.

[Nigel Graham 2Participant @nigelgraham2]

Thank you for all those tips, Julie.

Presumably letting the tin stand after all that rolling, is to allow any bubbles within the liquid, caused by the rolling, to rise and break?

I did think to try some of that with a small painting task just now, but the state of the rather old primer rather made the finer points, pointless. For this application, two small components for a piece of workshop equipment, it does not matter too much but I will have my steam-wagon to paint at some time, so all advice on obtaining a decent finish is welcome.

 

PS: At least I used newspaper to protect the washing-machine and microwave… (Yes, my paint-shop’s other duty is as kitchen!)

[Andy StopfordParticipant @andystopford50521]

I’ve had the same problem with the aerosol version of Paragon’s paint – it seemed to be reduced by using a heavy, wet coat (a somewhat scary procedure, but it seemed to respond well to it). I do wonder if it’s something that their’s is particularly prone to.

[Grindstone CowboyParticipant @grindstonecowboy]

I have seen videos of people getting bubbles out of uncured resin using a blowlamp played quickly over the surface – maybe the same principle might work?

Rob

[howardbParticipant @howardb]

From my experience years ago with International marine enamel on  wooden racing dinghies, always striving for the best level finish possible.

Are you thinning the paint enough?

Depending on the area you are painting you need to add thinners until the paint flows nicely off the brush and lay the finish off with a lightly loaded brush.

By “lay the paint off” I mean – with the handle of the brush at 45 degs or so pointing in the direction of brushing, lightly brush the finish out.

This all depends on temperature, are you trying to paint in cold conditions? Best finish will come from moderate warmth of the paint and what you are trying to paint.

 

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