larch planks

[hedgesparrow]

i bought some larch planks from my timber mill its 8inch wide by 2inch deep timber which i had rebated to slot together. i knew its was green so had to alow for drying out. that's my question how long will it take to dry in a kitchen so is warm. what i do not want to do is glue it together and it expands which it did so i took the 2"x1" batons of back let it settle then re-screwed to keep it level so can still use it as a table. and when it has seasoned whats best to treat it with to give it a watertight finish and bring the color of the larch out. love larch all my floors in bungalow are larch and have a lovely red hue to them. but they are 100 plus years old and as good as new

[ucoulddoit]

Hi hedgesparrow

 

Sounds as though what you're doing is a bit unconventional, but I've done plenty of things that others thought didn't follow the rules, which turned out well, so I'll be interested to hear how it goes.

 

Not sure from your e-mail about the timescales involved. Were the planks you bought literally sawn from a tree trunk and immediately taken into the house and used as a table top? Or had the sawmill cut the planks some time ago in which case they might have been semi-air dried when you took them away. The planks will shrink as they dry so if they are screwed to a batten, there is a risk they will split unless the screw holes are slotted in the batten. Most of the shrinkage occurs in the final stages of drying below a moisture content of about 20%, so although the planks may feel dry, the risk of splits and distortion increases with time until dry to suit the ambient humidity, probably between 8 to 10% in your kitchen.

 

Since the tongues and grooves are already cut, I think it would be advisable to keep the planks fitted together during drying to minimise the distortion between each plank. Otherwise you may find the planks just won't go together because they are all bent differently. I wouldn't glue the joints because the wood will continue to expand and contract. I don't have the exact figures to hand but I would guess a larch table top, 3feet wide, could move between 1/4 to 1/2 inch between summer to winter. It would need very long slotted holes in the table frame to accommodate this amount of movement and a high risk of a joint splitting.

 

Defects such as surface checking might occur if the planks are dried too quickly, but may not be a problem if a 'rustic' appearance is OK. The risk of serious defects would be much higher with hardwoods, especially oak which is hard to dry to produce high quality timber.

 

Finish - if the planks end up a bit distorted/rustic, then a subtle finish to seal the wood may be enough rather than a shiney/glossy coating which might look out of place. Many coats of wax would bring out the colour. but it might look good with an oil based varnish/polyurethane thinned 50/50 with turps and applied with a rag rather than a brush. That should soak in to seal the wood and bring out the colour. Main thing is to wipe off the finish after a few minutes rather than building it up in layers, just leave on what has soaked into the wood. Two or three applications should be fine and will look like an oiled finish but won't spoil if a hot cup or plate is sat on it. A pretty indestructible finish in fact which you can polish with wax.

 

Post some pictures when you're finished.

 

Andrew

[ucoulddoit]

Hedgesparrow

 

I was thinking again about gluing the planks together and realised my main concern was that if the planks are cupped appreciably when dry (curved across their width) it might not look too good if they are glued into one piece. But it occurred to me that you could dismantle to top when the wood is dry and have the planks planed/thicknesed so that they are flat, then glue them together. But still need to be careful about future movement/risk of splits.

 

Andrew

[hedgesparrow]

i do not know how long they had been at the timber yard not long. mistake made to start was it was screwed in place underneath this made it bow like a banana. so unscrewed it all and got it flat then as you suggested put batons on bottom and scwred only at ends to allow it to move. at present working fine and staying flat. what i will do is get a moisture meter as need it for logs so will check it for dpm and when its below 10% will glue together and take your suggestion of finish. have to say it looks nice and can get 14 people round it as we did christmas day. and it was a cheap table for its size cost me £50 for timber

[ucoulddoit]

Sounds as though it will be a lovely big table. I used larch for a fireplace and it is a terrific colour. Reminds me of old pitch pine which is almost impossible to get now.

 

Andrew

[hedgesparrow]

larch is so underrated its has such a lovely red color with the grains running through it. when its finished will take some photo,s of it at present i rather not. needs work when dry

[agg221]

This may be too late to help, given the work you've already done on it, but one way to keep table tops or similar flat when made of several planks is to look at the end grain and alternate 'smiling' and 'frowning'. When they try to cup, this means they alternate cupping upwards and downwards so the whole thing stays relatively flat.

 

Alec

[delabodge]

you could also add a smaller width board either end going the width of the table to stop the cupping,,,