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| Bridge masking http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=51875 |
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| Author: | Brad Goodman [ Wed May 01, 2019 9:05 am ] |
| Post subject: | Bridge masking |
Just wondering how you deal with masking for bridges. I have always masked before finishing. I seal the top, put masking tape on, position the bridge and scribe around it with an exacto knife. The only "problem" I have had with tis method is some very minor grain raising at the the edge of the bridge which can be seen at certain angles. My theory is that some of the water from the glue (Titebond) swells the grain? The other methods I have seen used is to finish the top then position the bridge and remove the finish by either scraping, routing or using paint stripper.... |
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| Author: | Clay S. [ Wed May 01, 2019 9:14 am ] |
| Post subject: | Re: Bridge masking |
"I have always masked before finishing. I seal the top, put masking tape on, position the bridge and scribe around it with an exacto knife." I do something similar, except that I trace around the bridge then cut inside of the line with an exacto knife so the masked area is slightly smaller than the bridge footprint. This allows me to make small adjustments to the bridge location after the finish is applied and the neck is final fitted, with only a minor amount of finish needing to be scraped off. |
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| Author: | jfmckenna [ Wed May 01, 2019 9:40 am ] |
| Post subject: | Re: Bridge masking |
I do the same as Clay. I will then sand a slight taper to the edge of the bridge to deal with any finish over hang. Some people rout the edge of the bridge. I do liek to make bridges as small as possible so I like to have the glue footprint as large as possible. The few times that I have tried finishing first then scraping back the finish I've fouled up the edge of the footprint. |
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| Author: | Michaeldc [ Wed May 01, 2019 9:49 am ] |
| Post subject: | Re: Bridge masking |
I also mask before finishing. I use the 3M Edge-lock tape and trim to the edge of bridge with a fresh exacto blade taking care to only cut the tape. I use two 1/16” brass brads and drilled through the saddle slot to index the bridge before trimming the masking tape and for the final glue-up (makes it so quick to glue the bridge on). Before gluing the bridge on, I reverse mask the bridge area and give the top a quick scrape with a razor blade. I leave the masking in place during leveling and buffing. M |
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| Author: | Colin North [ Wed May 01, 2019 10:03 am ] |
| Post subject: | Re: Bridge masking |
I use EV finishes, so waterbased. I raise the grain first, damp cloth, 2/3 times before finishing, sanding back P240. Otherwise I noticed I sometimes get what I think you were seeing with the TB. Then mask before finishing with Frisket film, 1 thou, matt, extra tack. Trace around the bridge then cut inside of the line with the back of a new scalpel blade so the masked area is slightly smaller than the bridge footprint and rout a ledge under the bridge to fit. |
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| Author: | ChuckH [ Wed May 01, 2019 9:17 pm ] |
| Post subject: | Re: Bridge masking |
Why not glue the bridge on first, tape off the bridge they spray finish? What’s your opinion to this method? Sent from my iPhone using Tapatalk |
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| Author: | Colin North [ Thu May 02, 2019 4:23 am ] |
| Post subject: | Re: Bridge masking |
ChuckH wrote: Why not glue the bridge on first, tape off the bridge they spray finish? What’s your opinion to this method? Sent from my iPhone using Tapatalk Surface tension causing the build-up of finish around the bridge/masking tape's vertical interection with the soundboard. |
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| Author: | bluescreek [ Thu May 02, 2019 5:42 am ] |
| Post subject: | Re: Bridge masking |
stopped masking when I started doing my own finishing makes for a speed bump when level sanding. There are many ways to do this so do what works best for you |
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| Author: | B. Howard [ Thu May 02, 2019 5:52 am ] |
| Post subject: | Re: Bridge masking |
I do not mask bridges, causes to much grief finishing around tape... might as well just glue on the bridge and work around it. Here is how I do it.https://howardguitars.blogspot.com/2016/05/setting-bridge-on-new-acoustic.html |
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| Author: | Woodie G [ Thu May 02, 2019 6:00 am ] |
| Post subject: | Re: Bridge masking |
A blue tape mask will be 3-4 mil thick and definitely a bit of a 'speed bump' as Mr. Hall mentioned...if the finish is around 4 mil, sanding may go through the lacquer and into the tape, allowing water intrusion into the bridge patch. A 1 mil Frisket mask under a 4 mil finish is felt only for a moment when starting the P400 sanding, then is not noticeable. Re: wetting out the top...it's worth using distilled water for this step if the shop supply is mineral-rich...woods with higher tannic acid content such as some mahoganies can iron-stain, and it's never a bad idea to minimize the number of contaminants on the surface when working with finishes. Here is a link to the sort of thin, high tack film mentioned by Mr. North: https://www.amazon.com/Grafix-Extra-Fri ... B0065F1OS6 |
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| Author: | guitarjtb [ Thu May 02, 2019 7:10 am ] |
| Post subject: | Re: Bridge masking |
If you choose to scribe the finish around the bridge, I have found that it is safer to use a sewing needle than a razor or exacto blade. The point of the needle is easier to control, won't ride out into the finish, won't cut the wood underneath the finish, won't cut into the edge of the bridge, and makes a very small and accurate line. I have a needle inserted into the end of a short wooden dowel just for this purpose. |
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| Author: | jfmckenna [ Thu May 02, 2019 7:33 am ] |
| Post subject: | Re: Bridge masking |
I just might try that routing method next time. That's a pretty slick idea. I hate getting a router that close to a finished instrument though but looks easy enough. |
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| Author: | Terence Kennedy [ Thu May 02, 2019 8:23 am ] |
| Post subject: | Re: Bridge masking |
I have always routed or scraped off the finish. I like to position the bridge as the absolutely last step after the neck is in it’s final position. |
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| Author: | Brad Goodman [ Thu May 02, 2019 2:57 pm ] |
| Post subject: | Re: Bridge masking |
Thanks for all the replies. As usual a lot of ways to skin the proverbial cat..... It's always fun to change the way you do things after 45 years... I am considering the routing method...maybe.... |
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| Author: | Brad Goodman [ Thu May 02, 2019 3:24 pm ] |
| Post subject: | Re: Bridge masking |
ChuckH wrote: Why not glue the bridge on first, tape off the bridge they spray finish? What’s your opinion to this method? Sent from my iPhone using Tapatalk Chuck, I have found that It is hard to buff around the bridge. |
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| Author: | Brad Goodman [ Thu May 02, 2019 3:26 pm ] |
| Post subject: | Re: Bridge masking |
Woodie G wrote: A blue tape mask will be 3-4 mil thick and definitely a bit of a 'speed bump' as Mr. Hall mentioned...if the finish is around 4 mil, sanding may go through the lacquer and into the tape, allowing water intrusion into the bridge patch. A 1 mil Frisket mask under a 4 mil finish is felt only for a moment when starting the P400 sanding, then is not noticeable. Re: wetting out the top...it's worth using distilled water for this step if the shop supply is mineral-rich...woods with higher tannic acid content such as some mahoganies can iron-stain, and it's never a bad idea to minimize the number of contaminants on the surface when working with finishes. Here is a link to the sort of thin, high tack film mentioned by Mr. North: https://www.amazon.com/Grafix-Extra-Fri ... B0065F1OS6 Thanks for the link -I ordered it. I would like to try it. |
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| Author: | jfmckenna [ Thu May 02, 2019 3:41 pm ] |
| Post subject: | Re: Bridge masking |
I built a few classical guitars with the bridge glued on first. That was mainly done so that I could string the guitar up in the white, something I don't do anymore. It's definitely harder to finish that way but I would not equate it to using making tape. And the reason why you make the masking tape footprint smaller then the actual bridge is so that once done you can cut out that ramping effect. |
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| Author: | SteveSmith [ Thu May 02, 2019 3:53 pm ] |
| Post subject: | Re: Bridge masking |
I've used the routing method for about 10 years. I just tried Frisket on the latest (French polished) and really like it. Of course you have to be able to locate the bridge accurately. I route the saddle slot after the guitar is together so that gives me a bit of leeway. |
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| Author: | Terence Kennedy [ Thu May 02, 2019 7:07 pm ] |
| Post subject: | Re: Bridge masking |
The routing method is not a slam dunk either. I have used it for probably 15 years coupled with a small ledge routed into the bridge. Learned it at the Charles Fox course. 1/8" bit on the StewMac base. I have noticed, at least on my guitars that the finish may be just a bit thicker at the wings compared to the center with a top that has a radius. I typically don't go all the way down to wood with the rout but probably get 80% of the finish off and finish with small sanding blocks and scrape. It always seems like the finish ledge is just a tad thicker at the ends of the wings. Anyone else noticed this? Also, since the bit is round you need to square off the corners of the wings by hand and at first I had a couple of bridges lift because the wing was held up by a poorly squared corner. I also had a couple of issues when I thought I was down to bare wood but there was still some sealer/shellac present. Sometimes it is hard for me to be sure you are really at bare wood. I usually have to look it with the light at different angles and there seems to be a certain feel when sanding/scraping. Even with routing it is still a pretty tedious process for me and can consume a couple of hours easily. |
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| Author: | Brad Goodman [ Thu May 02, 2019 8:14 pm ] |
| Post subject: | Re: Bridge masking |
Terence Kennedy wrote: The routing method is not a slam dunk either. I have used it for probably 15 years coupled with a small ledge routed into the bridge. Learned it at the Charles Fox course. 1/8" bit on the StewMac base. I have noticed, at least on my guitars that the finish may be just a bit thicker at the wings compared to the center with a top that has a radius. I typically don't go all the way down to wood with the rout but probably get 80% of the finish off and finish with small sanding blocks and scrape. It always seems like the finish ledge is just a tad thicker at the ends of the wings. Anyone else noticed this? Also, since the bit is round you need to square off the corners of the wings by hand and at first I had a couple of bridges lift because the wing was held up by a poorly squared corner. I also had a couple of issues when I thought I was down to bare wood but there was still some sealer/shellac present. Sometimes it is hard for me to be sure you are really at bare wood. I usually have to look it with the light at different angles and there seems to be a certain feel when sanding/scraping. Even with routing it is still a pretty tedious process for me and can consume a couple of hours easily. All methods have pros and cons... I have never had a bridge lift on a guitar so I must be doing something right! It takes me around 20 minutes to peel the tape and prep the area for gluing the bridge. I have never routed a ledge on the bridge-it just fits perfectly in the space I have allowed for it. |
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| Author: | sdsollod [ Thu May 02, 2019 9:41 pm ] |
| Post subject: | Re: Bridge masking |
Why would you want to use high tack? I’d prefer low tack so that fibers aren’t pulled up when you remove the film... does frisked come in low tack? |
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| Author: | SteveSmith [ Fri May 03, 2019 6:26 am ] |
| Post subject: | Re: Bridge masking |
I just used the regular Frisket I got from Amazon. I wouldn't consider it to be high-tack, more like medium. No issues on an Adi top after it had been on several weeks. |
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| Author: | Woodie G [ Fri May 03, 2019 6:32 am ] |
| Post subject: | Re: Bridge masking |
It is relative...low tack frisket film is very low tack indeed, while high tack film seems about as tacky as 3M blue multi-surface tape, which seems fairly easy to remove without issue. High tack film does a better job of sealing if the seal coat ends up a tad heavy, so saves some time on cleanup. |
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| Author: | Colin North [ Fri May 03, 2019 8:00 am ] |
| Post subject: | Re: Bridge masking |
What Woodie said, never had a problem with fibres lifting |
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| Author: | Brad Goodman [ Mon Jun 10, 2019 1:29 pm ] |
| Post subject: | Re: Bridge masking |
Woodie G wrote: A blue tape mask will be 3-4 mil thick and definitely a bit of a 'speed bump' as Mr. Hall mentioned...if the finish is around 4 mil, sanding may go through the lacquer and into the tape, allowing water intrusion into the bridge patch. A 1 mil Frisket mask under a 4 mil finish is felt only for a moment when starting the P400 sanding, then is not noticeable. Re: wetting out the top...it's worth using distilled water for this step if the shop supply is mineral-rich...woods with higher tannic acid content such as some mahoganies can iron-stain, and it's never a bad idea to minimize the number of contaminants on the surface when working with finishes. Here is a link to the sort of thin, high tack film mentioned by Mr. North: https://www.amazon.com/Grafix-Extra-Fri ... B0065F1OS6 I bought the frisket tape and liked it. The tape came off easy enough- The only problem I had was that it seemed to leave more residue than masking tape-Used naptha to remove it. |
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