Harp Modifications
There are a number of things you can do to make your harmonica overblow better.
Most of these techniques are aimed at making the reed respond better to the player.

1. Gapping the reeds will affect the reed's response to pressure.
2. Arcing the reed will  change the reeds behaviour when bent.
3. wax or nailpolish is used to stop squeeking reeds
4. Embossing narrows the slot to minimize leakage.
5. Tip scooping changes the airflow around the reed.
6. Corner rounding allows a reed to be gapped low without it sticking.

It must be said that almost all modifications to the harmonica that are aimed at improving the responsiveness of the reed will have a very clear side effect; the reeds will sound more brightly thatn they did before. This effect is most noticable in reeds that are embossed and is even a reason for some players to not use these modifications because they do'nt like the sound it produces.
User Contributed Notes
17-09-2014 19:52
Thanks for all the information in this site!
I have an uncustomised seydel session steel G harmonica and while overblowing, the blow reed get sometimes stuck, especially at the 1st hole but sometimes also in holes 4 and 5. I try to blow softly as in a simple blow. What modification can i do, or is it a problem that a good technique can solve?
20-03-2012 13:12
No the coverplates are fine as they are. Maybe you can do a video on that :)
20-03-2012 04:29
vas a realizar videos de como preparar los coverplate.?

you are making videos of how to prepare the coverplate.?
08-03-2012 13:51
@Miguel: No not really :)
08-03-2012 05:28
jaja do you speak spanish?
08-03-2012 05:25
how can I make an aluminum comb whit my name in it ?

¿cómo puedo hacer un peine de aluminio con mi nombre en el?
08-03-2012 01:32
Oh wait the spanish was more clear. Yes I guess you can. You can get a clear comb and have it engraved or have someone print your name or other text on it.
08-03-2012 01:25
@Miguel: I didn't understand that last one :)
08-03-2012 01:23
esta bien. pero como puedo hacerme un peine de aluminio con mi nombre o alguna letra.?

okay. but as I can become an aluminum comb my name or any letter.?
08-03-2012 00:33
@Miguel: no, since people are making combs of metal and plastics we have no more need for wooden combs
07-03-2012 21:16
hola, excelente pagina, muy bien explicado.
sobre temas de peine: preparados de peine de de madera, micro pore, impermeabilizcion de la madera,etc. van a haber tutoriales?

Hello, excellent site, very well explained.
Comb issues: wooden comb preparations, micro pore, impermeabilizcion of wood, etc. will have tutorials?
08-11-2011 23:18
Okay. I'm starting to get my tongue to relax more. I'll probably try some minor modifications soon. Thanks again!
08-11-2011 02:09
@Peter: good to hear that you got your first overblow. Most harmonicas will overblow fine after a little gapping and maybe a little wax on the rivet. It would definitively be better if you can play the overblows without tension, but you can also overblow when tongue blocking so it isn't impossible.
08-11-2011 01:26
Thanks for getting back to me! About ten minutes ago I got my first overblow ever and I am psyched. You're right, though, it sounds terrible and I can't hold it for long. I'm sure I will improve in time. My main concern is improving without putting too much of a strain on my wallet for the level that I'm at. One more question now that I've got it--I know that you're not supposed to use the tip of your tongue for the over blow. But for some reason, even though I can do it with the H-spot, the tip of my tongue seems to want to slide up and perform the overblow whether I want it to or not. To counter this, I've been pressing my tongue up against the bottom of the harmonica to make it tense so the tip can't slide up but I can still manipulate the middle. I'm being very careful not to use the tip of my tongue. Would it be better or easier in the long run for me to learn to overblow using the H-spot without having this tension in my tongue? Thanks a ton for your help!
05-11-2011 12:44
@Peter: you can overblow without changing the harp. It will be more difficult and not as stable, but if you have a decent quality harmonica it will work just fine. If you are worried about the sound then you don't even have to start overblowing, when you are learning to play them the overblows will sound really bad so you will probably give up on them anyway.
05-11-2011 05:15
Hey, great site! Thanks for the help. Question--is it possible to learn to overblow without changing the reeds? I want to learn but I'm not sure I trust myself with the risk of damaging my harp. I also am not sure I will like the sound and I don't want to risk that, either. Any comments or suggestions?
01-10-2010 14:11
I always retune to ET whenever I get new reedplates
30-09-2010 19:19
Do you have any comments about equal temperment versus just intonation (or inbetweeneers like most harps are)?
30-09-2010 19:16
Can you please draw some diagrams of the modifications. I am not always able to do them correctlly (but when I do, WOW)

29-04-2009 05:35
I consider myself as a strong player with a developed tone and musical background. My question is about the elusive A note found by drawing the 3rd hole on a C harmonica.
I know you can get a G blow in the 3, a G# on the draw, chromatically up to the A, next a Bb, and finally the B natural - all by drawing in the 3 whole. But really, that A draw on the 3 hole - gosh darn it - it sounds so choked no matter how well I play it; and I can play it. I want to know is there a modification I can do that allows greeter ease, clarity, tone, fullness in that 3 whole draw? Turns out that A note is really important. I just want it too sound the best it can be. Please help.
Thank you
Richmond Va
16-10-2008 18:14
Will Vogtman
A B harp is a Cb Harp--unless you are REALLY into orchestral interpretations/microtones.

Get a B harp and re-label it. Ta-da! Cb harp.

Few people plaw blues in F#. But if you play in a band that tunes down a half step, the "Cb" will play second position "Gb" rather nicely.
29-05-2008 21:32
Edward Connell wrote:...Have you ever played/created/sold a C flat Harp?.....
I would love to try one as it would accompany the G harp of my friend during music composure.

Am I missing something here? What does the G harp have to do with it? Do you have any idea what you're talking about anyway? :-)
29-05-2008 12:29
Yes it is possible to overblow a harp without modifications. Some will squeel and some will be difficult to controll, but that depends on the harp model. The special 20 and the GM should work pretty well.
29-05-2008 02:28
IS it possible to do OB without any modification on my harp?
I use both SP20s and GM from Hohner.
19-05-2007 13:24
I think I would just buy a B harp and live with the enharmonic mysteries. But if you don't want to do that then you can always retune a regular C harp. I have tuned a low D harp down to a low C. quite a bit of work but it can be done fairly easily. Get out your sanding paper and make yourself a Cb / B harp.

I think that B harps are always the ones that stay behind on the shelves in the musicstores. Nobody wants to play blues in F# so they sell very few of them I guess.
19-05-2007 08:17
Edward Connell
I have approached a number of musicians,harmonica suppliers and Blues harp suppliers with this question:
Have you ever played/created/sold a C flat Harp?

To this date may 19 2007 I have not found a C flat Harp.
I would love to try one as it would accompany the G harp of my friend during music composure.
I presently use a C sharp.
Do you have knowledge of getting/plaing a C Flat Harp?
09-01-2006 08:25
Alastair Wilson
I found all the information on harp modification really useful.
Well done.