Cabinet Door Bow

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DavidRa

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Hi and a Merry Christmas to all,
I made a cabinet to hide a wall mounted boiler for my daughter and the door has bowed slightly so I am looking for some views on why. It would be a step forward not to make that same error again!
The cabinet door ( 830mm x 510mm) is made of 12 mm mdf laminated ( & screwed) with 6mm mdf (55mm) to give a "shaker" look. Paint & let dry one side at a time. It was flat when I made it but bowed overnight, not massively but 2+ mm along the height so enough that I notice it.

Is it, a) the painting on one side at a time , b) the materials , would plywood have bowed less? c) the lamination process, should I have gone traditional rail & stile and inserted a panel.

Any thoughts greatly appreciated.
 

Jones

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Probably all of the above. Standard MDF does like to soak up moisture. I like to seal with a shellac type sealer which has a meths/alcohol solvent which won't swell the mdf and dries quickly , then use normal paint. Plywood can still twist even the best stuff. A framed panelled door might be better but only if you select the timber well. The good news is it should be easy to bend back just put the ends on spacers ,say 3mm and weight the centre ,overnight should be enough.
 

DavidRa

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Probably all of the above. Standard MDF does like to soak up moisture. I like to seal with a shellac type sealer which has a meths/alcohol solvent which won't swell the mdf and dries quickly , then use normal paint. Plywood can still twist even the best stuff. A framed panelled door might be better but only if you select the timber well. The good news is it should be easy to bend back just put the ends on spacers ,say 3mm and weight the centre ,overnight should be enough.
Thanks for that, much appreciated. What proportions do you use on your shellac mix?
 

Jones

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You can use a thinned down shellac till it's almost water consistency or any paint with a meths solvent often sold as stain blocking such as Zisser bin or Rustins MDF sealer. They dry fast typically 15 minutes so you can do both sides at almost the same time and don't add water and the solvent evaporates quickly.
 

DavidRa

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You can use a thinned down shellac till it's almost water consistency or any paint with a meths solvent often sold as stain blocking such as Zisser bin or Rustins MDF sealer. They dry fast typically 15 minutes so you can do both sides at almost the same time and don't add water and the solvent evaporates quickly.
Thanks
 

thetyreman

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it's near a boiler which is a source of heat that's what caused it! hot on one side cold on the other, that often causes warping, other than that make sure you cover both sides evenly with equal coats, which sounds like what you did anyway, maybe more layers of paint will help.
 

owen

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I've heard of doors made this way (6mm glued onto 12mm to give shaker style warping before. Maybe time to get a router and slot cutter and make proper frame and panel doors? Other than that, putting 6mm pieces on the inside of the door might pull the door back straight.
 

DavidRa

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it's near a boiler which is a source of heat that's what caused it! hot on one side cold on the other, that often causes warping, other than that make sure you cover both sides evenly with equal coats, which sounds like what you did anyway, maybe more layers of paint will help.
I hadn’t put it up but now that I have I will see if it moves even more!
 

DavidRa

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I've heard of doors made this way (6mm glued onto 12mm to give shaker style warping before. Maybe time to get a router and slot cutter and make proper frame and panel doors? Other than that, putting 6mm pieces on the inside of the door might pull the door back straight.
Do have a router table but was trying this method for the first , and possibly last , time
 
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