HEy i am building a low q tempest subwoofer.....but i dont have thetempest just yet.....i was wondering.....can i build the box then leave it for about 6 months or so till i get the tempest and ava250amp????? nothing would happen to the mdf if it just sits there with no use right??? ior do i need to treat the wood with some sort of preserve or something?????
MDF is actually thick paper, it atracts moisture, but kept in the same environment as You plan to use the finished speaker, it will last as long with or without driver, if You´ve got a cat the empty cabinet will soon be turned into real estate.
I had a small sheet of 3/4" mdf in the garage, and through sitting there for 4 months on the floor, it is now 1" thick mdf and in bad shape.
--
Brian
--
Brian
Keep it dry and flat, it soaks up water like a sponge, just not as fast
Most types of wood will bend if not stored on a flat surface
Most types of wood will bend if not stored on a flat surface
MDF
Hi, you could paint a first coat of paint/ on both the inside and outside of the box, that would make it inert and less likely to absord humidity.
Happy listening,
Dan
Hi, you could paint a first coat of paint/ on both the inside and outside of the box, that would make it inert and less likely to absord humidity.
Happy listening,
Dan
it's all about humidity...
here in Singapore it is always 90%+ humidity and MDF always swells unless you seal it after construction with some form of waterproof barrier (Think along the lines of sound deadening bitumen lining inside and paint/varnish on the outside...
simple really, if you live in a dry climate, you would likely never have any such problem.
You can actually buy an impregnated version of MDF here which is double the normal price but is waterproofed.
here in Singapore it is always 90%+ humidity and MDF always swells unless you seal it after construction with some form of waterproof barrier (Think along the lines of sound deadening bitumen lining inside and paint/varnish on the outside...
simple really, if you live in a dry climate, you would likely never have any such problem.
You can actually buy an impregnated version of MDF here which is double the normal price but is waterproofed.
Sealing MDF
Despite some misconceptions to the contrary, MDF is an excellent product to use for speaker cabinets. All wood products will absorb and dissipate water with changes in humidity and in this regard MDF is no different. Unfortunately however the process is somewhat one way with MDF and is compounded by the fact that that the swelling associated with high humidity disrupts the bonding between the MDF particles (ie it falls apart!).
There are two ways to work around this. As mentioned above, either use MDF products specifically designed for high humidity environments, they are generally used in bathrooms etc. Asking your local merchant for “wet area MDF” is nothing kinky.
Alternatively, protect conventional MDF by forming a water barrier. Yes paint and, good grief, tar, will work, but may not be compatible with subsequent finishes, or if you want to veneer the cabinet etc etc. The best way is to protect the edges with PVA glue sizing. That sounds fancy but is simply normal white PVA glue (think white paper glue) that you thin with water until it looks like milk. Use a paint brush and give it a few coats on any exposed edges. By the way, this is also good practice anytime you’re edge gluing MDF as it tends to soak up the glue and can starve the joint. Simply coat as described and allow to dry, then apply glue as per normal.
The faces of MDF rarely need sealing but in REALLY humid environments such as in the tropics you can apply a few coats of shellac. It’s quite extraordinary to think with all the technology there has yet to be anything better developed for this purpose than the old bug poo. Mix shellac flakes with alcohol (you may read about different “cuts” of x amount shellac flakes to y amount alcohol, well that’s fine if you’re French Polishing, for now put some flakes in a jar and pour enough alcohol in to just cover), go pour some of the more tasty alcohol for yourself and come back a few hours later once it’s dissolved, you’ll need to give it a shake every so often. Adopt a French accent and apply with a brush or a rubber … ah no not that kind of rubber, it’s basically a fancy rolled up cloth. It dries VERY fast so by the time you’ve finished you can normally start the second coat.
That’s it. As mentioned you don’t normally need to seal MDF unless it’s in exceptional environments. Unsealed wood you intend to use in projects should never, never, never, did I say never? EVER be left on bare concrete floors as the floor is very high in moisture. Leaving MDF standing on bare concrete will kill it in no time. In a workshop it’s best so seal the floor but if that’s not possible then put some “sacrificial” solid wood “stickers” under the MDF sheets and rest the MDF (or solid wood) on them.
Hope that helps.
Cheers,
Pete
Despite some misconceptions to the contrary, MDF is an excellent product to use for speaker cabinets. All wood products will absorb and dissipate water with changes in humidity and in this regard MDF is no different. Unfortunately however the process is somewhat one way with MDF and is compounded by the fact that that the swelling associated with high humidity disrupts the bonding between the MDF particles (ie it falls apart!).
There are two ways to work around this. As mentioned above, either use MDF products specifically designed for high humidity environments, they are generally used in bathrooms etc. Asking your local merchant for “wet area MDF” is nothing kinky.
Alternatively, protect conventional MDF by forming a water barrier. Yes paint and, good grief, tar, will work, but may not be compatible with subsequent finishes, or if you want to veneer the cabinet etc etc. The best way is to protect the edges with PVA glue sizing. That sounds fancy but is simply normal white PVA glue (think white paper glue) that you thin with water until it looks like milk. Use a paint brush and give it a few coats on any exposed edges. By the way, this is also good practice anytime you’re edge gluing MDF as it tends to soak up the glue and can starve the joint. Simply coat as described and allow to dry, then apply glue as per normal.
The faces of MDF rarely need sealing but in REALLY humid environments such as in the tropics you can apply a few coats of shellac. It’s quite extraordinary to think with all the technology there has yet to be anything better developed for this purpose than the old bug poo. Mix shellac flakes with alcohol (you may read about different “cuts” of x amount shellac flakes to y amount alcohol, well that’s fine if you’re French Polishing, for now put some flakes in a jar and pour enough alcohol in to just cover), go pour some of the more tasty alcohol for yourself and come back a few hours later once it’s dissolved, you’ll need to give it a shake every so often. Adopt a French accent and apply with a brush or a rubber … ah no not that kind of rubber, it’s basically a fancy rolled up cloth. It dries VERY fast so by the time you’ve finished you can normally start the second coat.
That’s it. As mentioned you don’t normally need to seal MDF unless it’s in exceptional environments. Unsealed wood you intend to use in projects should never, never, never, did I say never? EVER be left on bare concrete floors as the floor is very high in moisture. Leaving MDF standing on bare concrete will kill it in no time. In a workshop it’s best so seal the floor but if that’s not possible then put some “sacrificial” solid wood “stickers” under the MDF sheets and rest the MDF (or solid wood) on them.
Hope that helps.
Cheers,
Pete
reply
What is E1 MDF then?????😕
Because I got some sitting in a damp shed for about a year and it still is as good as new condition.
Maybe it's special MDF like for use in bathrooms as it's dark brown in colour.Maybe it's the 'wet area MDF' your talking about.
But what does the E1 STAND FOR???
What is E1 MDF then?????😕
Because I got some sitting in a damp shed for about a year and it still is as good as new condition.
Maybe it's special MDF like for use in bathrooms as it's dark brown in colour.Maybe it's the 'wet area MDF' your talking about.
But what does the E1 STAND FOR???
In Australia, there is a product called MR-MDF, the MR meaning moisture resistant. It is used in wet areas. There is, dare I say it, a MR resistant version of chipboard for those who prefer that product ( this is identified by a green thin stripe running through the middle of length of the sheet).
There should be a version of it available in most countries.
The product here is distributed by Laminex which is an american owned company so I wouldn't doubt its availability in USA or even Europe though perhaps under a different brand name.
These products resist swelling but I wouldn't recommend storing the speaker boxes in buckets of water all the same!
MADINOZ
There should be a version of it available in most countries.
The product here is distributed by Laminex which is an american owned company so I wouldn't doubt its availability in USA or even Europe though perhaps under a different brand name.
These products resist swelling but I wouldn't recommend storing the speaker boxes in buckets of water all the same!
MADINOZ
I believe E1 is just standard chipboard but can't confirm this.
However while on the subject please be careful when machining MDF as the dust is VERY nasty stuff. A good quality dust mask is essential whenever machining or sanding MDF.
Cheers,
Pete
However while on the subject please be careful when machining MDF as the dust is VERY nasty stuff. A good quality dust mask is essential whenever machining or sanding MDF.
Cheers,
Pete
Thanks for the comments, Pete.
I like the ideas you've proposed for keeping MDF from swelling. My first set of DIY cabinets looked great when I built them (veneer and MDF stored in the room of use for a month prior to assembling) but we had a cold snap right after I finished them. One cabinet had splits in the veneer immediately, but afterward, no other problems. Regretfully, a year later and a series of AC vs. Heat cycles later, the veneer has split in many areas. Looks OK to most, but horrible to me.
I think I might try the shellac or white glue sealing method for the outside and a tar type interior coating in the future as I use AC/Heat to maintain the inside environment I want to live in, with the obvious humidity changes that come with the territory.
Thanks for the comments.
Sandy.
I like the ideas you've proposed for keeping MDF from swelling. My first set of DIY cabinets looked great when I built them (veneer and MDF stored in the room of use for a month prior to assembling) but we had a cold snap right after I finished them. One cabinet had splits in the veneer immediately, but afterward, no other problems. Regretfully, a year later and a series of AC vs. Heat cycles later, the veneer has split in many areas. Looks OK to most, but horrible to me.
I think I might try the shellac or white glue sealing method for the outside and a tar type interior coating in the future as I use AC/Heat to maintain the inside environment I want to live in, with the obvious humidity changes that come with the territory.
Thanks for the comments.
Sandy.
Sandy, from what you mentioned I’d suggest the “problem” in your case is not with the MDF but with the veneer.
As mentioned in a previous post, moisture from the air (or another surface it’s placed upon) transfers in and out of the wood, and as it does so the wood expands and contracts. Think of it as being “alive” in a sense, expanding with high humidity and contracting when the humidity drops. MDF, because of its construction, is resilient to this effect and it is not normally a problem to be considered when designing using this material. As noted above, up to a limit, get it too high in moisture and things start turning funky 🙂 However solid wood (and veneer is simply very thin sheets of solid wood) can expand and contract considerably, mostly across the grain, and needs to be considered when designing a project.
For example, assuming something possessed you to want to build a cabinet out of solid timber and you did so in the middle of winter when the air in your nicely heated garage is very dry. Chances are that the wood panels will eventually explode the joints one summer when the humidity is high unless you allowed a gap for expansion; not really practical in a sealed box design! I once saw an extreme case of this where a coffee table top was constructed with the timber running across, rather than down, it’s length. The top expanded approximately 2-3 inches along it’s length! Ergh what a mess, asked how to fix it the reply was simple … the bin is over there.
Normally once veneer is glued to a substrate (eg MDF) the glue bond is strong enough to resist the thin veneer’s movement. However if the veneer is attached using normal white PVA glue a couple of factors come into play. Firstly, the veneer soaks up the moisture in the glue and expands. That wouldn’t be a problem except for the second factor that PVA glue has a tendency to “creep” ie it remains slightly pliable after curing. This allows the veneer to contract when the humidity drops (ie when it’s cold) however the glue prevents even contraction across its width. The end result is cracking, generally at the ends.
Sealing a wood surface is one answer, but then in our plastic world one I personally despise. A much better result will generally be found both by considering how the wood will move and designing with this in mind in the first place, and using the correct materials for the job.
Cheers,
Pete
As mentioned in a previous post, moisture from the air (or another surface it’s placed upon) transfers in and out of the wood, and as it does so the wood expands and contracts. Think of it as being “alive” in a sense, expanding with high humidity and contracting when the humidity drops. MDF, because of its construction, is resilient to this effect and it is not normally a problem to be considered when designing using this material. As noted above, up to a limit, get it too high in moisture and things start turning funky 🙂 However solid wood (and veneer is simply very thin sheets of solid wood) can expand and contract considerably, mostly across the grain, and needs to be considered when designing a project.
For example, assuming something possessed you to want to build a cabinet out of solid timber and you did so in the middle of winter when the air in your nicely heated garage is very dry. Chances are that the wood panels will eventually explode the joints one summer when the humidity is high unless you allowed a gap for expansion; not really practical in a sealed box design! I once saw an extreme case of this where a coffee table top was constructed with the timber running across, rather than down, it’s length. The top expanded approximately 2-3 inches along it’s length! Ergh what a mess, asked how to fix it the reply was simple … the bin is over there.
Normally once veneer is glued to a substrate (eg MDF) the glue bond is strong enough to resist the thin veneer’s movement. However if the veneer is attached using normal white PVA glue a couple of factors come into play. Firstly, the veneer soaks up the moisture in the glue and expands. That wouldn’t be a problem except for the second factor that PVA glue has a tendency to “creep” ie it remains slightly pliable after curing. This allows the veneer to contract when the humidity drops (ie when it’s cold) however the glue prevents even contraction across its width. The end result is cracking, generally at the ends.
Sealing a wood surface is one answer, but then in our plastic world one I personally despise. A much better result will generally be found both by considering how the wood will move and designing with this in mind in the first place, and using the correct materials for the job.
Cheers,
Pete
- Status
- Not open for further replies.