Knots!

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timeless
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Knots!

Post by timeless »

Hello

Newbie and clueless here.

I was just wondering what you might do about knots in the moulding for hand-finished frames. They kind of show through the paint, even after loads of coats. Are there clever ways to deal with them that I just don't know about, or do you just keep piling on the paint, or are knots generally viewed as 'okay to have'?

I only frame up old things (no idea how to frame a picture), and quite often try to make the frame itself seem old and weathered to match the object, so generally knots are OK for me. But for this frame, I was hoping to make it quite neat and tidy rather than old and worn. See the big circle in the top left corner? Plus the one above the third window? Not to mention the little dimple out of the right hand bit.

Image

These are bow brooches from fifth century Greece (B.C. that is - around the time of Sparta vs Persia, if you've seen 300!) Please excuse the amateurish framing, I've only been doing it for a couple of months.

Thanks for any help!

Jon

P.s I can't seem to photograph squarely so have to use software to make the frame orthagonal (which buggers various other things in the picture - the label window is straight in real life)
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Re: Knots!

Post by Not your average framer »

As you are talking about knots, I am assuming that this mainly applies to pine frame mouldings. If this is the case, it may be helpful to be aware that not all pine mouldings are using the same grades of pine. Narrow mouldings using selected grade pine very often are knot free in most lengths. Some suppliers may have some mouldings using this grade of pine. Ungraded pine mouldings have a much more noticeable level of knots.

I found out about this by observation over time and then asking my supplier why this. Some mouldings were produced from selected grade pine, while there were others produced from ungraded pine. Beyond this I try to not include knots in moulding that I use for frames, depending upon the size of the frame in question, there may be practical limits determining how successful this may be.

I'm not much into making pine frames with visible knots, so as far as possible I try to use the wood in between the knots and put the knotty bits into the dumpster. As most pine mouldings are quite in-expensive, this is often a useful thing to do.
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prospero
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Re: Knots!

Post by prospero »

You can get that moulding in Obeche. :lol:

If I get a big knot in a pine moulding I generally drill it out and use Brummer Stopping to fill the hole. Bit of a faff,
but it does save bumps. If the knot is 'dead' then you have to do this anyway as they are going to be loose.
A live knot will bleed sap and this can eventually show through the paint. If you leave them in it's best to give them a dab
with shellac before painting.
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Re: Knots!

Post by vintage frames »

I like what you're doing with the frame. Welcome to the hapless world of hand finishing. If the knot is bleeding it's dark resin, which it will anyway, there is a stuff called Patent Knotting, widely available. It's only a very thick shellac that seals in the resins. So put that on first.
You're still going to be left with the imprint that can show under a smooth top coat of paint. Then the best thing to do is to smear over the knot with woodfiller - not the stuff in a tube but the tin of two part filler available from any good finishing supplier. Smear it over with your gloved finger and when it's set, sand back down to the level of the wood. This is also good for filling up any dings.
Or - as Prospero said - buy the moulding in obeche.
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Re: Knots!

Post by Not your average framer »

I've been using the two part wood filler like that for years, but I've never mentioned it on the forum because I was not sure how other members would respond to it. I can't say that I've ever encountered anything in print, or on the interenet promoting it at all, but it does seem to work well in my own experience. I was thinking that if I suggested it that it might not go down all that well.

I like pine mouldings, but I do try to avoid the ones produced from knotty and therefore resinous wood. I think that there is a lot less effort needed to hand finish the less resinous pine in comparison to the more resinous and knotty varieties, so the whole process of using such mouldings tends to make more sense to me. My preference for these mouldings is to use relatively quick and easy finishes and price them accordingly.

Sure, you can do really nice up market frames using pine as well, but seeing that many of the mainly knot free pine mouldings are narrower mouldings they tend to lend themselves to making nice frames with a nice hand finished appearance at a more acceptable price for customers are willing to pay a bit extra, but not too much extra.

I can get quite a considerable mark up for such frames, while the labour component required to do this is kept to a reasonable level. Being smaller mouldings, there is a limit to the frame sizes that you would want to use such mouldings for and this means that it is much easier to avoid using wood where a knot occurs, without encountering hardly any increased cost of waste.

I get a reasonable proportion of small framing orders from this and the same small stock of these smaller pine mouldings allows me to offer an apparently substantial range of different finished mouldings from the relatively small stock of bare wood mouldings. I find that this works very nicely for me and in addition to this I also make up various stacked mouldings also using the same basic moulding stock.
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Re: Knots!

Post by timeless »

That's great advice, thanks Prospero, Vintage and NYAF. I wonder if I can get away with sanding/filling the frame as is, then repainting, rather than scrapping the whole thing and starting again. I'll have a crack at it tomorrow!

Thanks again.

Jon
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Re: Knots!

Post by Not your average framer »

timeless wrote:I wonder if I can get away with sanding/filling the frame as is, then repainting, rather than scrapping the whole thing and starting again.
I think that is not a straight forward question to answer and others may be better at answering that than me, but for what it's worth I'll share my thoughts a little and see where that gets us. I am ready to be shot down in flames here, or corrected by others with specific experience beyond my own, so if anyone else wants to jump in with their own take on this, please do so.

I personally think that Prosperro's idea about drilling out and filling the knotshas a lot going for it, in so far as it removes the knot completely and a knot that is no longer there is not going to be causing any problems at a later date. However, if you will then be applying a water based finish over the filler and the surrounding wood and the added filler, then you have the possibility of the water content in the water based finish causing the grain in the wood to rise and consequently be visible through the final finish.

So you may need to counter this effect. Basically you either use a primer which will not cause the grain to rise in the first place, or you bury the risen grain under something that you can sand down to a completely smooth finish. As you may have perhaps guessed from my posts over the years, I'm not much into sanding down layers of of primer, or paint until I have obtained a dead smooth finish, so I'll leave that to others prefer this method to discuss their favorite methods.

I'm of the other persuasion! If I can avoid using wood containing a knot by cutting around knots and throwing the odd knotty bit in the waste bin, I avoid the problem and it's consequences completely. If the area of the filler is going to be pretty much difficult to see under the paint , or primer, because there is not enough showing to matter, then that's good too. If it becomes necessary to use a non water based primer, then a lot of us will have our own favorite primer and methods, don't necessarily discard any methods mentioned on here by any other experienced hand finishing framers. If they work, that should be good enough!

I like to cheat a little, which does not mean that the more traditional methods are in any way lacking, but coat over already filled knots with quick drying matt varnish intended for protecting oil paintings. I paint over it while it is still slightly tacky and apply a little heat from a heat gun, this sticks the varnish and the water based acrylic paint together really well and after cooling and drying, the paint withstands the finger nail scratch test extremely well.

I am reluctant to use wood with obviously too much resin in a knots and if there is no other option, I heat the knot with a hot air gun to make the resin bubble out of the knot, followed by scraping away the residue, sanding down and cleaning off any remaining resin residue with a strong mixture of solvents. My thinking behind this is that the wood will never be subjected again to such high temperatures and the already applied high temperatures should have removed any amounts of resin likely to escape at more normal temperatures. I don't know how I would go about proving my thinking, but my intuition is that this seems a sensible solution.
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Re: Knots!

Post by timeless »

Thanks for your detailed reply, Mark.

I can see why it's easier to just avoid them in the first place! Maybe I'll reframe it then - I'm quite used to screwing up and starting from scratch! :)

Incidentally, I was just wondering about the 'fingernail test'. I've been using acrylic based paints to hand-finish the frames (or sometimes I just stain/wax them), but for this one I used a tester can from Farrow and Ball. I've no idea if F&B paint is acryllic or not, but it's the first time I've used it. Should I be putting some sort of varnish/lacquer on it do you think, as I do with chalky paints?

Cheers

Jon
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Re: Knots!

Post by Not your average framer »

Farrow and Ball tester pots are not acrylic, they are from their estate emulsion range and are a thinner version of a chalky emulsion. There are not particularly tough paints, but they have a lovely silky feel and a really low level of sheen, which I appreciate very much. This does not mean that they won't do the job, far from it and there are ways of toughening up Farrow and Ball paints without degrading the qualities which we all like about their paints.

I like to add some Polyvine "dead flat" acrylic wax finish varnish, which has the same silky feel, but adds some extra durability. The ingredient which is added to produce the "dead flat" matt finish is coloidial silica which has the same hardness as grains of sand, although coloidial silica particules are very much smaller, being more like a powder. The coloidial part means that the silica stays in suspension in the varnish and does not settle out. The silica adds a reasonable degree of scuff resistance by virture of the fact that the silica particules suspended in the paint finish are very hard indeed and take a lot to wear them down.

BTW, I make a bit of a distiction between pine mouldings and most of wood types. I'm not saying that you can't produce superior quality frames with pine, but I like the fact that by adapting one's techniques and methods you can produce some very saleable frames with less labour involvement. When it comes to many of my favorite moulding shapes, then many of these are not found in pine at all, with obeche being the most common wood particularly for larger profiles. So I would suggest that you have a good look at some of these as well, very often they are one of the best woods in terms of value for money and are ideal for hand finished paint based finishes.
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prospero
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Re: Knots!

Post by prospero »

If you want a dead smooth finish then you are in for a LOT of sanding. Really you should use trad gesso, brewed up
in a double boiler. The properties of such are tried and tested and have never been improved on since the time of the
ancient Egyptians. :D However, in the modern world we don't have all the time in the world and building up an immaculate
marble-smooth base is going to take hours/days/weeks. To my mind, unless you are doing water-gilding all the labour is OTT.
For a painted finish it is sufficient most of the time to merely fill the grain pores on hardwoods and make good any knots, splits
and blemishes on softwoods*.
I first join the frame and then examine it for any niggly bits. Also radius the corners slightly. Next a brushing over with
diluted fine-surface filler. this I wipe off/rub in with a J-cloth**. If you take your time at this stage it saves a lot of sanding. At
the same time I make good any mitre gaps and minor flaws with the filler full-strength****.
Next, When the filler has dried and the frame sanded, two coats of ripple paint***. This acts as a primer and also fills the grain
further. This applies to softwoods as well as hardwoods. At this stage you can see any rough patches of grain that were not apparent
earlier. Sand down any patches of raised grain as you go. Two coats is generally sufficient. You can add more and the more you do the
smoother base you'll get, but after a certain point extra coats produce diminishing improvements.
Sand the ripple paint down and you get a nice base for the acrylic top coats. Good quality artist's grade acrylics are very tough when
dry. Non-soluble and waterproof. You can use emulsion-type paints for a top coat, but they are not as durable. Waxing then is OK and
you can also varnish them. The surface might not be dead smooth. Not like a machine extruded moulding. But personally a few brushmarks
and undulations do not detract from the look. It's a handmade product. You can even emphasise the 'imperfections' to produce pleasing
textures. Adds touch of humanity. As long as it's even all the way round. :P

Thing is, if you take time and trouble to prepare the wood surface you should not have to go back and make good any flaws.
Like most other things in life, preparation is the key. :wink:

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
* When I say 'Hardwood' and 'Softwood', I'm talking in the botanical sense. Some Hardwoods are very soft and most Softwoods are harder
than some Hardwoods.

** You can buy cleaning cloths from EBay and such in bulk. Don't get them from the local Co-op as you'll get through 100s. :lol:

*** The ripple paint I've used for years from Wickes has been discontinued. :| I'm currently testing some B&Q jollop which looks OK..... :roll:

**** This is fine for small gaps/holes. For bigger ones it's best the use a wood stopping. I use Brummer Stopping which is more akin to wood
than Polyfilla-type stuff. It's got more body. A big void will need to be filled in stages, the final one well proud of the wood surface. Do this
and sand it flush before you start grain filling.


Here Endeth Today's Lesson. :clap: :ninja:
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Re: Knots!

Post by Not your average framer »

Well said Peter. I think that covers it all in not particularly many words.
prospero wrote:A big void will need to be filled in stages
True, but if you're pushed for time, two part wood filler will usually fill it in one go! Filling with two part wood filler and sanding down afterwards gets easier as you practice, so don't worry if the first time you do this, it needs a bit of working on. A little practice and you'll be an expert in no time!
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Re: Knots!

Post by vintage frames »

I would take your own advice and repair the frame. It's a painted finish, so that's going to be easy to repeat. Sand back the existing finish - doesn't have to be complete - and fill the knots with the two part filler. Let it set as said before and then sand back to the surface of the wood. Then re-paint.
I'd never be shy about using two part wood filler. It's real use is as a repair product and not a wood finishing product and since it's going to be painted over with an opaque paint, it would be my first choice to use.
I'm always curious by forum discussions on the "durability" of the finishes many use. Apart from a little wax, I don't see the need to protect the frame any further after painting. Most here seem to use acrylic paints. So you've effectively covered the frame in coloured plastic - what more protection does it need?
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Re: Knots!

Post by Not your average framer »

I presume that it would have been me who first mentioned durability. Well, I think it is fair enough to question my mentioning durability and I think that I would have to say that this became an issue for me a very long time ago, in the earlier days of my framing. One customer somehow after having the frame for a while, decided that the aging wash on the frame was a build up of dirt and therefore to clean it with who knows what and complained that the finish came off when she tried to clean it.

There were one, two other equally stupid cases and I started trying to find ways of stopping this, including a lady who brought the frame in to prove that she could scrape away some of the finish with her finger nail. Sadly, it's is very hard to convince such people, especially when they are elderly that this is not fair treatment, so I started to take a lot of care to make sure that finishes are deliberately tough and durable. So I've been doing it ever since and like you say, it should not be necessary to do this.

BTW, some people like to use some of these all purpose, all surface cleaners and these can be a bit too aggresive as well.
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Re: Knots!

Post by timeless »

Thanks again for all the advice. I had a go at it today (sanding/filling/repainting) with less than desirable results :) It's just inexperience I guess, I'll have another crack at it tomorrow. From now on, I'm buying obeche! Also, I'll pop to B&Q tomorrow for some fine-surface filler (never heard of it before).

I'm used to slapping on acrylic paint then rubbing it down a bit with a paper towel. I guess the 'mattness' of the F&B paint made me think it'd scratch off with a fingernail. I'll leave it alone though if it's tough enough already.

Thanks again!

Jon
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Re: Knots!

Post by prospero »

I use the 'No-Nonsense' fine surface filler from Screwfix. It's good and it's cheap. :D

I recently got through 2kgs of it on a big order. :shock:


I've only had one customer who didn't 'get' aged/distressed finishes. "I don't want that. It's all dusty". :roll:
They are the sort of folks who, if they dropped a Ming vase would say thank goodness it wasn't a new one. :lol:

I like my finishes tough. Most of my frames get shifted about from pillar to post around exhibitions. In and out of cars
and are liable to dings. If they do get dings, I can usually fix them easily. That is one plus with pine. It doesn't dent quite as
easily as Obeche.
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Re: Knots!

Post by vintage frames »

I'll agree with you. It's a sort of horses for courses argument for durable finishes. If your work is going to get traipsed around, thumbed and scuffed, then a harder protection can help.
I have found, however that if a very hard varnished finish is marked in some way, then the damage appears more obvious and out of character than would have been seen on a simple waxed finish. Another good argument for hand finishing frames.
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Re: Knots!

Post by Not your average framer »

I would agree about hard finishes. I don't think that hardness and durability are necessarily the same thing. Coloidial silica is an extremely finely powered material are just resists abrasion when whatever is causing the abrasion starts to rub against the silica that is embeded in the paint, or varnish.
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Re: Knots!

Post by timeless »

Thanks again guys. Much appreciated information!

Just for context - this is what I'm framing: http://www.timeless.gallery Unfortunately, I know a lot more about the antiquities than I do framing techniques! I was taught the basics last year by the excellent Crome Galleries in Norfolk, but am now discovering that 'the basics' is really all I know. Also, my mountboard cutter doesn't have any production stops, so I tends to overcut a bit as I'm doing it by eye, but I'm getting better at that, and it's quicker than using stops.

It doesn't feel right putting something old in a shiny new frame (unless it's artficially aged driftwood or something), so I hand-finish everything and try to make it look weathered. But what I'd really like to be able to do is this, which I saw in a local furniture shop!

Image

Do you reckon they just cut up and planed old bits of wood to do that?

Cheers

Jon
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Re: Knots!

Post by prospero »

:P I've got stacks of old wood that I've saved over the years with the vague intention of making frames.
Some came out of the house next door - floorboards/skirtings etc. Must be 200 years old. Some has been
outside and is well weathered and worm-eaten. I even saved the slats off the fence when blew down. :lol:
The thing is, you would have to stabilise it somehow without destroying the character. I haven't tried doing this yet.
It's on the to-do list.
I think it would need to be brought inside for a while to dry out (which might introduce more splits and cracks) and treated
with fungicide. Some of my stuff has things growing on it. The more warpy pieces would maybe be used as facing with a new
more regular sub-frame to form the basic structure.

If I ever get around to it I'll post the results. Some people go mad for ratty old wood frames. :clap:
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Re: Knots!

Post by vintage frames »

Could indeed be some old lengths of wood. Certainly by the look of the split piece at the top. You do have to be careful when planing old timber, so as not to plane out the patina that marks it as old. Go too deep and you've got the same as fresh timber!
If you do use old timber then the best way is to scrub it first with water and Vim/Ajax ( if you can find any ) and then sand it up a bit. After that a varnish and wax will bring out the colour again or just leave it for that dry scrubbed look.
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