A mate of mine builds radio controlled planes (using epoxy to lay up sheets for the body and wings) and is planning on painting them using epoxy based paints from these guys: http://www.baronpaints.co.uk/index.htm
He's not actually sprayed any of the stuff yet, but, depending on how my epoxy experiments go, he's offered to test some MDF pieces for me at some point.
He thinks the chemical make-up of the two products is probably very different... not that we've checked on the tubs.
He's not actually sprayed any of the stuff yet, but, depending on how my epoxy experiments go, he's offered to test some MDF pieces for me at some point.
He thinks the chemical make-up of the two products is probably very different... not that we've checked on the tubs.
Ed LaFontaine said:
Bob Barkto said:
Link to the type of paint I generally use:
http://www.overflex.com/Product.asp?frm_product_id=617&SBL=5
It's waterproof Ed. Satisfied?
Bob: The stuff I use, at the thickness it's applied, water vapor will not penetrate. Fluctuations in the relative hunidity or seasonal changes have no effect at all on the finished product. Sorry, but I have been doing this succesfully for years, and I don't live in a glass bubble. Where I live, the climate is very extreme, from +35 Celsius or more in the summer with high humidity to -20 in the winter and everything in between.
Somehow everyone seems to not get the most important point: make sure the MDF box is as dry as it can be before finishing.
Good thread, although I must admit that it seems that some people have over-reacted (at times) to perceived criticism.
I, to, live in an area with wide variations in temperature and humidity (0C to 45C, 5% to 100%). With the only pair of MDF boxes that I currently have, I have had no problems with expansion/contraction. They are sealed (design), are veneered (3/16" Tassie Oak) and clear sealed. The inside of the MDF was not treated in any way. So, I'm not sure what I've done right (or wrong, but without noticing).
The boxes that are being looked at here (Bob, Shin, MJ, anyone), are they sealed or ported (or other type of "inside of the box open to the elements) types? If they are 'open', has the MDF on the inside of the box been sealed or not? Could this be having an effect?
I'm going to collect both methods listed herein and anything else that comes up later. My MDF has been sitting round for about a year now and it's ready to build a box out of, and ditto for the ply for another pair of boxes.
I, to, live in an area with wide variations in temperature and humidity (0C to 45C, 5% to 100%). With the only pair of MDF boxes that I currently have, I have had no problems with expansion/contraction. They are sealed (design), are veneered (3/16" Tassie Oak) and clear sealed. The inside of the MDF was not treated in any way. So, I'm not sure what I've done right (or wrong, but without noticing).
The boxes that are being looked at here (Bob, Shin, MJ, anyone), are they sealed or ported (or other type of "inside of the box open to the elements) types? If they are 'open', has the MDF on the inside of the box been sealed or not? Could this be having an effect?
I'm going to collect both methods listed herein and anything else that comes up later. My MDF has been sitting round for about a year now and it's ready to build a box out of, and ditto for the ply for another pair of boxes.
Cloth Ears said:
Cloth Ears: The fact that your box is sealed helps the situation. When the box is ported, moist air can enter. Although it's my contention that the biggest problem comes from the initial drying out period after construction, too much moisture in the air that enters a speaker port can (potentially) cause a problem. Therefore it's a good idea to seal the inside too.
It's the finish that's being looked at, not so much the box. Shin is going for (and has accomplished) the classic "piano black", where you have a perfectly mirrored black surface. I have done the same, but used a different method. Although the method that I outlined seems daunting, it will give perfect consistant results if followed to the letter. Preperation, paint type, # of prime coats, # of paint coats, and most important: drying time. Be patient and don't take any shortcuts.
Bob Barkto said:
Bob, I fail to see the irony, as if you had finished them in the same way that I "claim" to use, there would be no problem.
Have you bothered to look through all of my posts on this and have a look at the pictures with them?
I do this kind of stuff for a living. I don't have anything to prove, just thought I'd pass on some good advice and teardown some myths while I was at it.
In my recent example the boxes are vented, and the veneer is nowhere near 3/8". More like 1/16" (don't have a scrap handy to measure).
MDF can't really be acclimated or seasoned in the same way solid wood can.
It fully reacts almost instantly to changes in RH.
It has to be brought to a certain mc and finished nearly immediately. Even overnight it will re-acclimate to it's surroundings.
Solid wood can take days, months or years, depending.
MDF can't really be acclimated or seasoned in the same way solid wood can.
It fully reacts almost instantly to changes in RH.
It has to be brought to a certain mc and finished nearly immediately. Even overnight it will re-acclimate to it's surroundings.
Solid wood can take days, months or years, depending.
Cloth Ears said:
I tend to keep my wood around for a year before I use it, so that I'm not bitten by changes in the wood after it being cut/created/pressed. So an extra couple of days/weeks after construction and prior to the finishing won't both me at all...
Cloth Ears said:
So an extra couple of days/weeks after construction and prior to the finishing won't both me at all...
There! That's exactly the right attitude of a successful build.
When I was younger, I tried to do it all in one day. Well, that just made a mess. Now that I've learned a thing or two, and can appreciate the value of a fine set of speakers, I take my time and do it right.
Just addressing your comment that I should "use the right finish".
Which, according to you, I did. I find that ironic.
Nothing pertaining to technique or process was mentioned or implied, by you in your reply, or by me.
I have used very similar techniques and materials as you describe with perfectly acceptable results.
There are exceptional cases where "your" method will be ineffective.
I also do this for a living. And I have skimmed your posts.
What you fail to realize is that your method, while sound and proper, is not the cure for the exceptional cases being discussed here.
While I certainly appreciate myth busting, I tend to do that myself, most of what is occurring here seems to be confusion in terminology, lack of experience and knowledge and a bit of the DIY syndrome.
In other words a reluctance to try or accept that some things just don't work or a professional solution is somehow anathema to a DIY effort.
I'm not bashing you or denigrating your efforts ad hoc. Just offering my opinion of your approach based on my experience.
No hard feelings.
Which, according to you, I did. I find that ironic.
Nothing pertaining to technique or process was mentioned or implied, by you in your reply, or by me.
I have used very similar techniques and materials as you describe with perfectly acceptable results.
There are exceptional cases where "your" method will be ineffective.
I also do this for a living. And I have skimmed your posts.
What you fail to realize is that your method, while sound and proper, is not the cure for the exceptional cases being discussed here.
While I certainly appreciate myth busting, I tend to do that myself, most of what is occurring here seems to be confusion in terminology, lack of experience and knowledge and a bit of the DIY syndrome.
In other words a reluctance to try or accept that some things just don't work or a professional solution is somehow anathema to a DIY effort.
I'm not bashing you or denigrating your efforts ad hoc. Just offering my opinion of your approach based on my experience.
No hard feelings.
MJL21193 said:
Old people
It's very easy to hurry. Even for "old timers" like ourselves.
I used to marvel at the impatience of "young" people.
Really, it's a myth that young people are more impatient.
20 years ago I was teaching a finishing course for "senior citizens". Most impatient lot you'll ever find.
Taught me a thing or two.
When I was young I learned how to do, then I did, then I taught.
Now I'm repeating the process!
It's very easy to hurry. Even for "old timers" like ourselves.
I used to marvel at the impatience of "young" people.
Really, it's a myth that young people are more impatient.
20 years ago I was teaching a finishing course for "senior citizens". Most impatient lot you'll ever find.
Taught me a thing or two.
When I was young I learned how to do, then I did, then I taught.
Now I'm repeating the process!
Cloth Ears said:
Bob, I realise this, but I am also lazy
I have never been younger than I am right now (43 & 5/6) - or if I have, then I try not to remember it... which is becoming easier all the time.
Bob Barkto said:
Bob, I've been on this thread from the start, and if there is an exceptional case that's been talked about, I must have missed it. I thought we were talking about MDF finishing problems? "My" method will withstand complete submersion in water with minimal harm. I think it's safe to say it's ready for the exceptional cases.
As far a busting myths, I'm into demystifying the speaker building process too. There's too much misinformation and half truths coming from every quarter, too much bickering about details that have no impact. I'm trying to introduce a little clear thinking and solid fact based information, so that the novice builder will not be beaten into not starting a project because he doesn't know all of all minute intricate details about things that don't matter.
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