Painting over cracked putty.

[chris French]

We have a window, where some of the putty was replaced last year (with standard linseed putty). for various reasons though it never got painted, and so of course the putty cracked as it dried.

In an ideal world I would no doubt remove it again and re-putty in fresh, but that ain't gonna happen.

So before painting I want to do something about the cracks. I wondered about mixing up some putty with some more linseed oil so make something softer/runnier and working that into the cracks first?

Or any other better suggestions?

[Mr Pounder]

The putty will come out very easily. Why botch it when you can redo it in the same time as the botch up?

>

[Ian Jackson]

In message , Mr Pounder writes

Rather than putty and linseed oil, you could use a mixture of putty and the correct colour oil-based paint. However, as it hardens in few minutes, I'm pretty sure I've used Plastic Padding (or similar car body filler paste) for such a purpose.

[chris French]

In message , Ian Jackson writes

Ah yes, now I should have thought of that, seeing as I have a tub of Isopon I've been using for wood filling :-)

Mr Pounder - the putty has been in best part of a year in a south facing window - whilst not hard, it certainly is firm enough to make removal harder than 'very easy' - it would take a lot longer to remove and reputty IMO than to fill a some cracks. It's also an old Victorian window with stained glass and the glass cracks easily - some panes with a glass I've not yet been able to source a suitable replacement for yet.

And if it was just a normal sized window I might well do it, but it's a bit more of a job than a couple of panes.... :-)

[george [dicegeorge]]

Isnt car body filler too hard for this job? Wouldnt external flexible frame filler be better? [g]

[Ian Jackson]

If it's only filling cracks, it probably doesn't matter. Anyway, I'm pretty sure that Plastic Padding is available both as soft (plastic) and hard (like Isopon and most others). Either type should do.

[chris French]

not sure what you are meaning by flexible frame filler? do you mean the sealant type stuff?

Car body works fine as a wood filler - is basically the same stuff as the two part 'external' wood fillers

[Mr Pounder]

You did not tell us that.

[chris French]

In message , Mr Pounder writes

No I didn't, I decided to keep the question short and sweet, and just say that reputting wasn't going to happen

[george [dicegeorge]]

its a tube of stuff for about £5 to go in a gun like the dozens of other types - silicon, gutter guard, glue etc but its called flexible frame filler I use it between wooden window frames and walls, the flexible-ness could be better than car body filler for patching cracks in putty.

I use car body filler to patch the wooden frames.

[g]

[Ian Jackson]

In message , "george [dicegeorge]" writes

For parching up cracks in putty, acrylic sealant and similar is probably a good alternative to car body filler, but you'll need to wait a day or two before you can paint it.

I have a fair amount of car body filler in the bottom of my garage doors (which were going rotten). The repairs will probably outlast the rest of the wood. The secret is using a mix of paste and resin - depending on how runny you want the filler to be, and if you want to try to get it to penetrate some of the not-too-rotten wood (so-called 'wood hardener' being pretty well useless for this purpose).

[js.b1]

If it is just a fine crack, scrap out a wedge and refill with putty. Do remember putty on the bottom & seal between the paint and glass matters most, the rest can be cracked and falling off. If a gap opens between the putty & glass it will serve to retain glass borne water and very rapidly rot through. Putty is quite tolerant of cracks if painted with a good alkyd undercoat & gloss, it fills them quite well.

Never apply a filler without first applying wood hardener. The wood hardener stabilises the wood from shrinking away from the filler and gives it something to bond to. Just check the next year nothing has opened, you can repair very severe rot in foggy saturated November with wood hardener but the following spring it can open a little around the filler, pipette in more wood hardener and all is happy thereafter.

Ensure the paint used is compatible with linseed oil putty, Trade Weathershield is however overcoatable paints like Sikkens Rubbol Undercoat & Rubbol do not adhere well to it (chips off or even falls off). Frame sealers can be more successful, but check for compatibility. The downside of Weathershield is it retains water underneath in its final year(s), I have watched relatively high moisture content pine rot in a couple of years with Weathershield as it forms a plastic bag of water, whereas the alternate timber above painted in sikkens Rubbol Undercoat & Rubbol actually went to low moisture content over the same period as it could breathe much better.

Very nice window and the brick arch & pointing are in great condition.