Sand Shading and scorching
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Sand Shading and Scorching
by Alf Murtell

Animation Alf tutorials 3
   
Sand shading (or scorching), as it’s name implies, is the art of applying heat to veneer in order to achieve shadow and depth in circumstances where it would not be possible to attain the required effect by inserting a piece of darker veneer into the work.

Sand shading-scorching can be used to give a smooth gradual darkening which is often impossible to achieve just by “cutting in” another piece of veneer. To demonstrate the overall effect, take a look at these examples of sand scorching (as we shall now refer to it) shown on this accompanying picture.

The Roses seen here owe a lot of their realism to sand scorching, for example, the depth and roundness shown in the petals, this couldn’t really be achieved with any other method. It can also be used successfully for shadows fading into corners, or even for scallops and sea shells such as you can see in this other picture.

Roses & Sea Shells
Coarse Sand

To acquaint yourself with sand scorching I would advise you to try experimenting with various veneers to see what kind of effect’s you can achieve.

Naturally the best veneers for sand scorching are the whiter veneers, such as sycamore, ash, or holly, any of these veneers would scorch well, but if you wish, you can make use of other veneers.

Mind you I have never had much success with the dyed variety of veneers, they never scorch with as much satisfaction as the whiter veneers do.

Now, we need at this juncture, to make some observations about the actual sand you could use.

You can use either coarse or fine sand, I have never found any real difference between the grades of sand myself, although some people do say that they think that coarse sand is the better, but the final choice is up to your own personal preferences.

You will want a pan to hold your sand, of which you will want a depth of about an inch to an inch and a half of the sand (approximately 2 – 3.5cms), you will also need a pair of pliers or tweezers and an electric stove (as an alternative you could make use of a gas stove or a “camping” or picnic type of heater). It will take a little while for your sand to heat up this will be roughly about 20 minutes or so. You will also be needing a spoon (a dessert spoon is ideal for this) but make sure it is not from your best cutlery otherwise you’ll invite a fair bit of domestic disharmony into the proceedings, because you will now need to place the spoon in a vice and squeeze the sides in so that the spoon forms a pouring spout (as you can see in this photo). This deformation will give you better control with the pouring of the hot sand.

I wouldn’t advise you to dip your veneer straight into the hot sand because you will burn it and you will have lost the desired effect, you will in fact have over burnt it. There are certain exceptions to this statement but I will be showing you them later on when I do the trellis and the basket weave demonstrations.

The Shaped Spoon
Alf tests the heat

Unfortunately with very small pieces you won’t be able to hold them and pour sand onto them, you will of necessity be obliged to dip them in the hot sand, but do be very careful and don’t burn them by leaving them in the hot sand for too long.

It’s time now for some practical work, I’ll just check the sand for heat by just letting some hot sand rest on the test piece of veneer for a few seconds, yes, that’s okay it’s scorching so I will turn the heat down a little.

You will notice that scorching has been taking place at the sides of the test veneer, so we are now at our correct heat.

Now when you cut your piece of veneer for scorching you can either cut your piece slightly oversize, or you can cut it to fit the “window”, the choice is yours.

Do bear in mind that the hot sand applied to the veneer will cause the veneer to shrink a little due to the effect of the heat causing some of the moisture in the wood to evaporate,

so it will be necessary to put some moisture back into the veneer to bring it back to it’s original size, this you can do by just putting the scorched veneer into your mouth, obviously, make sure its cooled slightly otherwise you’ll burn yourself.

If you elect to cut your piece of veneer oversize then it will only be necessary to trim your veneer to fit your window and then you will avoid having the taste of scorched veneer in your mouth. I would recommend that you lightly pencil the area you want to scorch for your own guidance when applying the hot sand. Don’t forget to apply the sand to both sides of your veneer so that you get penetration of the “scorch”.

When you apply the hot sand to the veneer, scorch slightly over the area you require, because you will lose some of the scorched effect when you come to sand your picture down. You cannot really get the scorching effect with dark woods, for example, a walnut, you can try sand scorching if you wish but you are not going to make hardly any impression on it at all. If you use a light walnut, it could perhaps be used to depict a corner of a room or ceiling.

Now, if you have a fair number of pieces to scorch, just scorch a few of these first and put them back into your picture, then do another few and put them in your picture, and carry on with this procedure until you have done all the pieces you wanted scorched for your picture.

Alf puts moisture back
Don't apply in centre

A question from the audience: “You don’t moisten the veneer until after you’ve scorched it Alf?” “Yes, that’s right, now if you assume that the piece of veneer you’ve just scorched is going back into your picture, you’ll probably find that there is now a gap around it even though it fitted perfectly before you scorched it, this will be due to shrinkage caused by moisture loss because of the effect of the hot sand, now you can overcome this problem by applying a little moisture, even the white PVA glue will help the situation. If you are not happy with this shrinkage problem you can overcome these drawbacks by just cutting your veneer oversize, sand scorching it and then cutting it into your window in the normal manner”.

Do not try placing hot sand into the middle of a leaf of veneer because it will start curling up and you will be unable to do anything of any practical use with it.

I must say that I’ve not had any real success with chemically treated veneers either. You can sometimes see a light scorching taking place, but it in no way compares with the depth of the effect you get when you scorch the white veneers.

Now do bear in mind that the sand in the centre of the tin is going to be the hottest, so don’t go plunging your veneer into that part of the hot sand and then after a while bring it out from that part of the sand only to find that you now have a charred piece of veneer, it is far better to control the application of the hot sand by pouring it on your veneer with the spoon. As I said before, with small pieces you will not be able to do that, but with your larger pieces do use the spoon to apply the sand onto your veneer, leave it for a few seconds then pour the sand back into the tin. You can repeat this process until you’ve achieved the depth of scorching that you require.

If you take a look at the roses on the demonstration board you will find that they’ve scorched just right, they show about the right amount of shadow and depth, after all, you do not want the wood blackened by over doing the amount of scorching.

Apply sand with spoon
Vicky has a go

Alf: “anyone like to have a try?” Vicky volunteers.

Alf: “I’ll just check that the heat’s okay for you” Vicky now applies some hot sand to a piece of test veneer by using the spoon method.

Alf: “there you are, you can see the discolouration taking place, now turn it over and do the other side, ------ there, that’s now a sufficient depth of colouring”

Dave Walker: “don’t forget to place the veneer in your mouth to resize it!”

A question from the audience: “Can I dip the piece of veneer into water instead of placing it in my mouth?” “Yes, but do not let it soak, test it out on a spare piece of scrap veneer first, or use the other alternative of cutting your veneer oversize”

Another question from the audience: “Can you use coloured dyed veneers?” “I have, as I said previously, never had any success with dyed veneers, but do try experimenting with these types of wood because you may be successful”

There is one wood I would not recommend you to use, and that is Paduak, this is a red wood and it bleeds its colour very easily, when it is scorched it just crumbles and you just end up wasting your time and your materials. As I said earlier, the best results are obtained with the use of the white woods, sycamore, holly, horse chestnut and ash to name just a few. But do experiment because it is all a case of trial and error. It is well worth the effort and the time you put into getting yourself the desired effect.

Can you use dyed veneers
Full view of equipment

A further question from the audience: “What sort of sand do you use Alf?” “I use any sort of soft or sharp sand. I think this is actually sharp sand that I am using for this demonstration. Many people say that they find sharp sand is the best”

Another question from the audience: “A lot of the secret of it Alf must be the amount of heat you put into the sand?” “It takes roughly about 20 minutes to heat the sand, you can easily get the sand too hot, so do a test with a scrap piece of veneer before you commit any of your picture veneers to the hot sand, one last point though is don’t leave the spoon in the hot sand while you are scorching otherwise you’ll end up not only scorching your veneer, but you will burn your little marquetarian’s fingers into the bargain when you go to pick up the spoon again!”

An over heard remark from Harry Heyford to Derek Batts: “I do the sand scorching in my shed, I bought a little Calor gas burner and I use it down there” “What, did you set the shed on fire?” “Well, yes, but……..”

Final applause from the audience.

End of the Lecture.

Alf's next lectures in this series will cover the topics of Trellis and Basket weave

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