Peg and green wood turning

[woodwork wally]

Hi I am new to green wood turning and peg . I have obtained about 15 litres of peg on ebay but no instructions or spec sheet . the drum is looking sad so firstly can it be stored in plastic [clean] plaster drums
also can anyone advise the proceedure for treating green wood with peg . thanks for any help given and regards to all Wally:B

[Skew ChiDAMN!!]

Hi I am new to green wood turning and peg . I have obtained about 15 litres of peg on ebay but no instructions or spec sheet . the drum is looking sad so firstly can it be stored in plastic [clean] plaster drums
also can anyone advise the proceedure for treating green wood with peg . thanks for any help given and regards to all Wally:B

Liquid PEG? Not the stuff I know, then, which was like wax. PolyEthylene Glycol (PEG) comes in different molecular weights, from about 100 to something like 10000. (Don't quote me on those figures... I'm pulling 'em out of thin air. :-) Different weights = different uses; most woodies use around PEG-1000. Hope I'm not the bearer of bad news?

here's (http://www.12bmedia.com/carpentry/woodworking/peg-1000--polyethylene-glycol.html) a link that I bookmarked back when I had a fiddle with the stuff, you may find some useful info there.

Hmmm... a quick search also found this (http://4umi.com/wood/conservation/endingthebending.htm) which is more relevant to bending wood but it says this about PEG:


PEG

Think of a situation where we cannot use mechanical methods of straightening. In such a situation, some magic may be done using polyethylene glycol (PEG). PEG is a watery polymer that has been developed by the Frenchman Charles Wurtz in 1859, but came into use for conservation of particularly waterlogged timber in the second half of the 20th century. In theory it is reversible, but once it has penetrated the wood, chances are it will stay there. Imagine trying to dissolve and remove an impregnated material from frail timber with veneer and a historic surface finish... Reversibility sounds great, but in practice the removal of PEG from a piece of wood would probably cause worse damage than before as it would need the introduction of a lot of water. So, given that practical reversibility does not exist and that it is imperative to consolidate rather than loose an object, we might as well be a little bit more intrusive. PEG differs from other common wood consolidants in its strong chemical affinity for cellulose. It swells the wood cell walls where as other stabilizers simply fill the voids between the cells. Softwoods tend to respond better than hardwoods, perhaps because there is relatively more cellulose in it. The same goes for reaction wood, where the cells walls are the thickest.


H H H H
| | | |
H - O - C - ( C - O - C )n - C - O - H
| | | |
H H H H

There are several types of PEG available, depending on the n in the chemical formula HO-CH2-(CH2-O-CH2) n-CH2-OH. The molecular weight may vary from 200 up to 58000. The most common types used in furniture conservation are PEG 400, which is liquid at room temperature, PEG 1000 which comes in blocks or flakes, and PEG 1500 in the form of pearls. In fresh or only slightly degraded wood with swollen but still intact cell walls, low molecular weight PEG can partly replace the water within the cell walls and thus keep them swollen when the residual water evaporates. In case the cell walls have lost their mechanical strength as in waterlogged timber, a high molecular weight PEG is needed to bulk the cell lumina.

The lower the molecular weight, the more effective the treatment is, but a disadvantage of low MW PEG is that it is also more hygroscopic. Wood treated with PEG 400 could therefore become damp in humid conditions perhaps too easily. A great deal of research is still needed in order to refine a warpage treatment from a trial and error process into a predictable and reliable procedure. Many variables affect the outcome: species, density, and thickness of the wood, the glycol MW, temperature and concentration of the solution, the effect of pre-swelling with mere water, etcetera, but what is known now is promising.

How do we use PEG? First of all, the concave surface to be treated is wetted thoroughly using towels or paper and covering the whole with a plastic sheet to slow evaporation. Where there is a glue joint or something like a veneered edgebanding, a parafin dam can prevent the moisture from wetting the veneer and glue. Also knots and burrs are to be avoided, as they will cause severe problems when the cells swell and the grain straightens, as you can imagine. After several hours, a reduction of the warpage can be seen.

Meanwhile, prepare a 30% solution of PEG. It dissolves easier in warm water, but should not be heated beyond 50 degrees Celsius. Gloves should be worn and contact with metal avoided as this will oxydize the PEG. Next, the solution is applied onto a clean tissue covering the wood and the plastic sheet is put back on top. Add some more the next morning, at noon and in the evening for the next four days. And be sure to cover the whole again with plastic after each application. Then, increase the concentration of PEG by applying it with a brush directly on the wood, and repeat this again several times a day for the next couple of days. Now a cellophane sheet is replaces the plastic sheet to allow some slow evaporation to happen. Once a blanched appearance has been obtained, the piece is left to dry slowly under the cellophane. Finally, the excess is removed with a damp cloth.

A few small remarks have to be taken into account: the treatment should be homogeneous and superficial, for if the penetration is too deep or unevenly spread over the wood, the treatment will lead to even more warping and other catastrophic results. It has been noticed that glycol continues to slightly swell a treated board for several months after treatment, presumably because there is free glycol in the cell voids which continues to be taken up into cell walls. On the other hand, it has also been noticed that the effect of a treatment using very low molecular weight PEG is reduced in time. Panels with PEG below 300 MW cupped back and this could be due to its volatility. A sealing agent may reduce this reduction.

As the PEG has a slightly greasy property, wood treated with it will not accept PVA glue but it will accept animal glue, although to a slightly lesser extent than untreated wood. Reglueing of a veneer on a panel treated with PEG may have a negative effect as the PEG is not able to counter the forces exerted by drying protein glues. Also applying a new finish may call for some problems. A tendency for treated surfaces to darken is noted. And last but not least, don't use PEG on timber which has been steambent as this would risk a undesired extreme straightening.

(Probably no help to you at all, but at least writing it kept me out of mischief for 5 mins. :D)

[woodwork wally]

Thanks SKEW much appreciated your efforts and some help in there but will need to go further so come on folks any help at all may be the link I am looking for Thank again Skew. Wally

[woodwork wally]

Hi again and SKEW thanks for that lead on RON KENT and his webb page That may mean no need for peg at all . Any one else intrested should take a look at www.ronkent.com (http://www.ronkent.com) and then go to techniques:- . he is using common Dish Washing Liquid . I can only assume that it is a good old common or garden home brand available at almost all stores . give it a go it turns easier . I have one on the floor in the rough to see if it splits or not I am going to try the liquid PEG in the same way but if the detergent works as good as it sounds then I would say PEG is on the way out price wise if for no other reason:2tsup:

"Keeping cost of sawdust and firewood down"