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Colouring water based filler

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Kittyhawk

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Firstly thanks to the administrators for approving my membership.

I have a hobby which has morphed into a little one man part time business in which I build scale model aircraft of any type to customers orders in recycled Rimu, a New Zealand native timber. Rimu has significant colour and grain variations, and I like to finish the models with six coats of Britax Teak Oil. Attached a picture of a P40 Kittyhawk to show the coloring/grain.
Unfortunately my eyes are not as good and my hand is not as steady as they once were. I put this down to the fact that I turned 65 well over a decade ago. This results in the occasional mishap which requires a small dollop of filler. I use a proprietary brand filler euphemistically called 'Rimu' but unlike any Rimu colour I've ever seen... when I've sanded with 400 grit the filler is invisible but with the teak oil applied the colour is invariably lighter that the surrounding wood, so I need to colour match the filler in situ, and I would welcome any ideas. Currently I am thinking to take a teaspoon of Teak Oil and mix something into it - wood stain, coffee, Brown shoe polish? and apply to the filler with a small artists brush prior to the full coats of Teak Oil. All suggestions appreciated.
Khawk2.JPG
 

kinverkid

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I have had a limited success with staining filler while mixing it. I found it better, but not ideal to stain it after I've sanded it back. If I apply the first coat of finish then let it dry I can then gently scrape the finish back off the filler. From there I can paint with stains or marker and keep building up the colour until it matches the surrounded area that has a finish on. When happy with the match continue to apply more finish coats. This chap has made a video on colour matching:
 

Kittyhawk

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Thank you. These pens sound ideal - I didn't know there was such a product. I will see what I can find here in NZ.
 

Sgian Dubh

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If, as you say, the filler is water based, then you should be able to adjust the colour through adding water based wood dye. A quick search revealed Carbatec in New Zealand may be one source. I imagine there are other NZ based suppliers of wood finishing products, but I didn't do any additional searching for you. I suspect you'd be best placed using the dry powder form of the dye you need that you would ordinarily dilute in water prior to use. In your case adding a little dry dye powder to your filler, plus a little water to adjust the filler viscosity might work best. You'd need to experiment a bit to establish what works for you.

Nicely made model, by the way. Slainte.

PS. You could also try using water soluble powder paint colours, such as those used by artists. Again, you'd need, ideally I suppose, to try and find a NZ source of artist's supplies for them.
 
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Kittyhawk

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Stunning workmanship, KH. Thanks for showing it and please keep posting examples of your work.
Thank you very much for your comment.
As you will have guessed, I do have an interest in aeroplanes. I started off this modelling in wood business by building a Mk 1V.B Spitfire which to my surprise sold quickly on TradeMe, the NZ version of EBay, and I thought that would be the end of it. But people then started to order specific aeroplanes, usually WW11 aircraft to which they had some family connection. This adds a whole new very enjoyable dimension to the process as well as forcing you to think about how to do some aspect of the model that you've never done before, especially as I do not have a woodworking background. Apparently this thinking stuff is beneficial for a person of my age so that's good. It's also the reason I joined this forum - I have a need for the expertise available here.
Concerning other aeroplanes, here is the anti-submarine version of the Wellington bomber, built for my neighbour. His uncle took off in HZ963 from Italy one morning in 1944 and was never seen again.

Wellington antisubmarine.JPG


And here the SR71 Bkackbird, built for a former pilot. For this I used a darker timber (Mahogany?) because the SR71 was built in dark Titanium.
sr72a.JPG

And a couple of Dakota's under build, in the background the military C47 version and the passenger DC3 in the foreground. The Dakotas were used here in the 50's for aerial topdressing.
DC3.C47.jpg

Because I don't really know what I'm doing or what equipment is available to perform certain woodworking functions I have built a weird and wonderful collection of tools to construct the models and I would encourage anyone to have a go at modelling in wood if you have the inclination. I have no interest in cars but have often thought that detailed wooden vintage cars would find a ready market.
 

mrpercysnodgrass

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While colouring filler with pigment can work well I think it is generally too imprecise for your needs. As you say you have the occasional small imperfection to disguise, so I think you will be better off touching these out with a paint on a fine brush then oiling over the top. You do not need to go to art school, with a few basic colours, a good brush and a little practice you will be able to make those blemishes disappear. An advantage of this method is if it is not right you can just wipe the colour off and start again or adjust in layers as you build your finish.
For your colour pallet a set like this will be good Winsor & Newton : Watercolour Sets but there are several colours you will not need so you could buy individual tubes like brown umber, yellow ochre, titanium white, Hookers Green, Indian red and mars black. The artist water colour tubes are very concentrated so think of them more like opaque oil paints and not the very translucent water colour paintings of the victorian masters! They are also colour fast which you will not get from those felt pen like stains.
This is an excellent brush for fine detail work and much cheaper than a good artist brush. Handover : Sable Mix Coachliner Lining Brush in Quill : Small Duck #2
 

Kittyhawk

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Thank you for your advise on the water colours and brushes. I had been thinking along those lines. The problem that I have with the aeroplanes is one particular area and that is where the wing joins the fuselage. Depending on the model - some are easy and no problem but with others it's a case of a compound curve on the wing root mating to a compound curve on the fuselage. As of now I am not good enough to always get a perfect fit hence the filler. And the problem is that the grain of wing and fuselage are at right angles to each other. So the filler will look more or less ok against the fuselage but ugly against the wing. I have come to the conclusion that whereas filler has its uses it is not a substitute for poor workmanship so I have to lift my game. But we have a little arty shop locally and I'm going to get a few tubes of watercolour. I have artists brushes and I'm going to give it a go.
Concerning filler, a cabinet maker friend who was workshop manager for a high end furniture business told me the following which I like to share.
We all love Rimu here in NZ for its grain and colour and ease of working. Unfortunately so does borer. Our woodworm borer will leave a nice round hole of about a mm in diameter. He says if you put filler in it, it will always look like what it is, a hole with filler in it even if it's colour matched. What they would do is stab the hole with the blade of a small penknife parallel with the grain and then put in the filler. Although the filler will still be visible it gives the impression of being a natural imperfection along the grain line. I have never tried it but I can see the point.
 

Richard_C

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I'v had some success using acrylic paint, its still water based and it's gel-like to handle so easier to work in. You can get inexpensive artists acrylic tubes and its easy to blend colours. It can dry a bit quickly, I put a tiny dab of each of the colours I am likley to want onto a saucer and blend with an artists paintbrush then work it into your filler.

I wonder if 'air dried clay, like DAS (but I'm sure there are other brands) would give you a finer finish than filler. Also available from artists shops.

Another trick is to use "sanding dust" blended into some woodglue.

Liberon used to produce wax filler sticks, mainly for dealing with scratches in furniture, but doubt its tough enough.

Model railway builders use all sorts of tricks, maybe see if there are some ideas to be borrowed from them.

Very nice work and I can see how it would appeal particularly for one-offs/unusual aircraft. My father flew 81 operations in a Martin Baltimore, no one does models now. If he were still alive I might have commissioned one. I do have a model that one of his aircraft fitters made in 1943, carved from perspex from a shattered canopy.
 

Kittyhawk

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Hello Richard. I am going to try paint and brush. Ultimately the aim is to upskill to where I don't need filler but at the moment I have a little mess to remedy on one aeroplane. I have mixed sawdust and white glue into a filler paste and it blends in well when sanded but goes pretty dark once the teak oil is applied. That is the problem - matched fillers look good sanded back, almost invisible in fact, but once the clear coating is applied the filler coloration becomes unpredictable.
I had never heard of the Martin Baltimore so I checked it out. Interesting looking aeroplane. From what I read it was a bit of a handful so your father must have been a skilled pilot, And fortunate to survive the dangers associated with flying an unescorted low level bomber. Great respect for those men.
 

baldkev

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Our woodworm borer will leave a nice round hole of about a mm in diameter. He says if you put filler in it, it will always look like what it is, a hole with filler in it even if it's colour matched. What they would do is stab the hole with the blade of a small penknife parallel with the grain and then put in the filler. Although the filler will still be visible it gives the impression of being a natural imperfection along the grain line. I have never tried it but I can see the point.

Thats a great tip. Maybe you could do a write up of your improvised tools, sounds interesting 👍
 

Kittyhawk

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Well I bought a few tubes of artist's water colours and got out my little sable brushes. I scribed a series of marks in a piece of timber, both with and across the grain and then filled with a matching filler and sanded down to 400 grit. As usual the matched filler was close to invisible when sanded but was pretty ugly when smeared over with a wet finger. I then tried endless mixing combinations of the paint but the results were disappointing to say the least. Either this is a very difficult skill to master or I'm just no good at it and as I mentioned in an earlier post I conclude my only real option is to improve my workmanship to the point where filler is just not required.
But one last thing to try is wood dust mixed with glue. I did a test using PVA glue/wood dust but with the same results - invisible when sanded but much darker than the surrounding wood when wet. Since I used sanding dust from the same piece of wood that was subsequently filled I wonder if the glue has something to do with it. Is PVA a suitable glue to mix with wood dust or should I try something else?
 

baldkev

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It has been suggested to use superglue instead which is apparently better but i havent as yet tried that one out....
 

baldkev

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Also, if possible, its better to use small wood chips instead of dust as there'll be less glue and more wood. Or is it possible to take a medium thickness shaving from a hand plane and in some way use that? how deep would the gap be?
 

joshvegas

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Could you adjust your build process to square up the join? Pretty sure some airfix models the bottom of the wind continues through and the top is notched to create a half lap join on the body. Leave the final shaping of the wing root until its all together type thing?

Lovely planes, my grandads uncle put a camel through a hedge in 19 having survived the war and my great uncle got one session of rocket practice in a typhoon before the war ended, think he was a wee bit gutted about not having a flying career after getting a taste.
 

Kittyhawk

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Could you adjust your build process to square up the join? Pretty sure some airfix models the bottom of the wind continues through and the top is notched to create a half lap join on the body. Leave the final shaping of the wing root until its all together type thing?
!
You're right on the money with your suggestion.
I have been experimenting with a mock up wing/fuselage assembly where each component contains compound curves. I think the way forward is to shape both bits as good as possible without going overboard on the joint, then offer the wing up to the fuselage and draw around the outline with a pencil. Then scrape within the pencil lines with a chisel or whatever to flatten the area out. Although the fuselage will still have a curve nose to tail, depending on the aeroplane type, the curve on the vertical axis can be eliminated so it will only be necessary to shape a one dimensional curve on the wing for a precise fit which should be within my capabilities and hopefully no more filler needed in my workshop. It worked ok on the mock up. About to start on two Mosquitoes which have a pretty curvaceous fuselage so will see how it goes in reality.
 

Kittyhawk

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Actually I feel a bit embarrassed about the above comment. One would think that after building somewhere over 40 aeroplanes I would have figured this out before...
 

joshvegas

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I'm not sure why you would be embarrassed. You've clearly developed a technique that works very very well probably changing things incrementally. That's the worst position to be in for spotting a big change.

I would echo the above comment about a rundown on your home made tools etc. I can't begin to imagine how manage to produce them!
 

Bm101

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Kittyhawk, I wonder if you have ever seen this technique/trick. Even a small off cut of steel will work like this for small areas by hand.
Bill Carter is a well known and highly skilled wooden planemaker. Also a true Gentleman.

Here he shows a easy technique for making scrapers that would be ideal for cleaning your plane wing/fuselage joints.
If (If!) you haven't used normal card scrapers before they would be another option worth a google.
Beautiful planes. Lovely. Glad you are posting them on here.
 
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