Applying filler to external woodwork - any quick solution?

[AJB Temple]

I am in the process of refurbishing a fairly large outbuilding. The whole building is being re-painted off white (previously dark green) and needs a good finish. I am using Sadolin superdec. Two coats. This is a good product with 8 year guarantee and excellent coverage.

This outbuilding was clad in the past with shiplap that has been nailed on with a nail gun by the look of it. On one side the nails lie about 1mm deep and I have filled them with two part filler and sanded flush. On the other three sides the nail gun must have had a different setting because I have around 400 holes about 5mm deep, that need to be filled (to prevent rust streaks as the nails are not galvanised unfortunately).

It is exceptionally laborious filling these by hand with a decorators knife, especially as the two part filler is quite stiff and goes off inside 20 minutes (so I have to work fast and cleanly).

Is there a better way? Deep holes are laborious to fill and I am wondering if I could use a syringe. The two part filler is too stiff for this though. It is essential that I can sand it flush afterwards.

Any advice?

AJ

 

[heimlaga]

Back in the days before galvanized nails some carpenter amongst others my grandfather used to punch the nail further in just to be able to protect them with a thicker layer of paint.
This practise proved to make the boards a lot more prone to rot in the long term and was abandoned.

There is nothing wrong with a few rust streaks on the outside of a building....... just a fact of life up here in the land of wooden buildings. The water which is sucked into the open end grain inside the nail holes is a much greater cause of concern.
Could you use Sikaflex?

 

[ColeyS1]

I'd be tempted to buy an eyewateringly expensive tube of ct1. Squirt it in about 30 holes, then have a filling knife and scrape the excess away. Two pack fillers alright but when the wood slightly moves, then the filler slightly shrinks it's gonna create looseness somewhere. Ct1 would give and move with the surrounding area. It's fantastic stuff, I've always got a tube at my disposal when I want to do a job once and only once

Coley

 

[Phil Pascoe]

Go to a glass fibre supplier and get a can of styrene (many motor factors keep it). Mix some in to soften the filler as you require. I bought some a few weeks back after years of meaning to, because I've thrown tin after tin of filler away for being too hard to use, and the day after I'd added a little the stuff was like new. I paid £6 some odd for 500 grammes, which will probably last my lifetime.

 

[AJB Temple]

Unfortunately rust streaks will not be acceptable to the eagle eyed female. The building is getting a high quality refurb whether I like it or not.

Thanks Coley, I have not used Ct1 before and had ruled out silicone type sealants as they do not respond well to sanding, but I will try this on an inconspicuous area. I was not aware it can even be applied in wet conditions.

I should add, this building is my main workshop. It is presently in a very conspicuous in part of our garden, visible from the house (albeit quite a distance away) and my wife is prepared to allow me to fill it with whatever machinery I like as long as the outside looks pretty. It is becoming part of her garden design and ties in with another building that is "hers". My life is made a lot easier when Mrs AJB is content. She has had her dad over from Germany for a week rubbing down these buildings and prepping them. The remaining filling is down to me and I am hoping he will be back soon to help with the painting!

 

[AJB Temple]

Phil, our posts crossed. I have never used styrene. Would it prevent the hardening agent from working?

 

[ColeyS1]

I'm not sure either if it would respond well to sanding, I could try a bit ? Would it be possible to do the sanding first then ct1 the hole smooth so no other sanding is needed ?

Coley

Sent from my SM-G900F using Tapatalk

 

[RickN]

No AJB, 2 part filler is pretty much on par with polyester resins adding styrene acts like adding thinners to paint, same applies to styrene to resin.
You would only need a small quantity to dilute the filler and I can't see that inhibiting the curing process.
I would make sure its well ventilated, as it stinks to high heaven. "high" being the operative word, it's small wonder I liked casting polyester so much.

 

[Phil Pascoe]

No - it's the solvent the stuff's made with - you actually need very little. I've used two part filler for decades and the only time I've known it fall out is when the wood's rotted around it.

 

[AJB Temple]

Coley - yes, the building is already sanded. It would have been better to fill before sanding, but my FIL wanted to crack on and he does not get on with two part filler. He does 6 fills (with a lot of excess smearing) in the same time I do 60. However, for practical reasons I am accepting his help.

Rick and Phil. Thanks. I will buy some styrene anyway as we need to repaint the entire barn at some stage (massive job) and there is a lot of making good to do. In fact I am almost tempted to re-clad it.

I must say, this forum is a hive of information. Super helpful.

AJ

 

[Jacob]

Dunno I think I'd dab the nail holes with red lead paint (or the modern equivalent) and then just prime and paint over, leaving the holes unfilled. If you fill them they are quite likely to pop out in time.
Incidentally - I'd use a linseed oil paint system (Allback etc) which will last far longer than any modern paint and cost a fraction.
8 year guarantees are meaningless - are they really going to come and paint your barn again?

The old systems are incredibly quick and easy to use, very cheap, very permanent, though linseed paints now are "modernised" old paints - no lead etc.

 

[AJB Temple]

Jacob, red lead is long gone. I think of my wife as a customer here. She does not want a building full of nail holes (and paint runs). She wants a smooth surface - and that is what she will get.

The advantage of the Sadolin paint is excellent coverage. I already have the paint so switching to something else just adds needless cost. I am using Brewers as my trade supplier and over 20 years or so of supplying me for development properties, they have given me good advice on finishes.

But thank you anyway.

AJ

 

[Jacob]

.. I think of my wife as a customer here. ...

Rule 1. The customer is always wrong. If they know better than you let them get on with it, while you look for a better customer who needs your skill and knowledge.

I'm serious about linseed paint. It's been a PITA seeing modern paints fail. I wish I'd known about it years ago.

 

[RobinBHM]

A few suggestions to think about:

MS polymer -good product but consistency of silicone not easy to tool
http://www.thegluepeople.co.uk/index.ph ... ucts_id=47

Exterior brummer -more of a hard traditional 1k filler, sets hard. Can be sanded ok.

Acylic paint filler 1 part -set quite hard, I use this for filling under remmers paint. Its probably not as good long term as more flexible options
http://www.remmers.co.uk/Product-catalo ... 0.html#bot

Repaircare dryflex
sfhttp://www.sealantsonline.co.uk/Produ ... ms/WIN7501

I would say the best product will be something that remains flexible, but has a reasonable ability to tool off cleanly. I use the repaicare dry seal for face puttying slimlite windows. Its a good product so the dryflex maybe good too. Probably not sandable

Filling nail holes is tricky, the problem is creating a good seal to avoid moisture getting in and allowing rust to form, yet having a product that can be tooled smooth. 2 pack sands nice and flat but has no flexibility.

A few different ideas anyway....

 

[MikeJhn]

Just an idea, but how about cellulose stopping filler, workable for longer and sands well?

Mike

 

[Woody2Shoes]

I've been trying to fix up some old south-facing painted softwood windows with rusty iron nails in them. Reading the instructions (!!!) on my Dulux trade primer tin leads me to suspect that Jacob's got a point.

If I were doing your job, I'd put some phosphate-based metal primer on the nail heads, let that dry and then squirt some of this in to fill the hole http://www.geocel.co.uk/catalogue/singl ... t-adhesive and smoothing it flat, before covering that with a water-based primer, then your favourite paint system.

Cheers, W2S

 

[Jacob]

Red lead paint is still available if you want to track it down but the usual alternative is "red oxide" which is iron oxide I believe.
I wouldn't use water based primer on anything external. Whatever you put on top will lift of eventually.

 

[MikeJhn]

Cellulose stopper is still used on vehicle bodywork under paint and you don't see many rusty cars now days, but if your nails are already rusty then that needs to be treated before you cover it with anything, the rust will eventually continue to oxidise and the eventual expansion will push whatever you have filled the hole with out of the way, or split the wood it is supposed to fix in place, beside treating each individual nail head with a rust inhibitor and then filling and painting, have you thought of taking the shiplap off and re-fixing with SS ring shank nails?

Mike

 

[AJB Temple]

This was supposed to be a quick job to keep my father in law busy! Replacing the shiplap is not a practical option: there is 100 square metres of it and I don't have time. There is nothing wrong with the existing timber - it is high quality and there is zero rot. The previous paint finish was also OK but not to the taste of my "customer".

I am not that concerned about the rusty nails in fact. The main problem is that they are punched in so deep and my wife wants a smooth finish. She already bought the paint, mixed to her colour spec,so that is what we are using as it cost £150 (at trade prices). I am happy with the Sadolin product for this job (but will re-examine linseed paints for the next job - tanks Jacob) : I have used it before in very exposed situations, and it has held up exceptionally well. The main benefit for me is that with two coats it self undercoats and will cover the dark green perfectly, even with a colour change to off white.

 

[Woody2Shoes]

Red lead paint is still available if you want to track it down but the usual alternative is "red oxide" which is iron oxide I believe.
I wouldn't use water based primer on anything external. Whatever you put on top will lift of eventually.

Zinc oxide or zinc phosphate I think - iron oxide's the stuff you're trying to avoid!

I'm wondering how big these nail holes are and how easy they'll be to see from any distance once the whole thing's painted anyway. You could fill them with linseed glazing putty - in the days before oil-based/acrylic/etc. sludge I suspect that's what got used in most situations like this (I know it was used to seal joints in cast iron guttering).

Re. the water-based primer, I foolishly read the instructions - I think this is specified to prevent bleed-through. I don't see why - in principle - a water-based primer should be any better or worse than an oil-based one (the oil/water is simply acting as a solvent after all).

Cheers, W2S