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Polyurethane over Sanding Sealer

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Clinton
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Hi, question that hopefully someone knows the proper way. 

  So, I intend to top coat with wipe on poly diluted with mineral spirits. 4-5 coats with wet sanding in between. Pretty standard right? However, I will be color dying it alcohol/water base. Generally, I would first coat it with sanding sealer to seal and if using lacquer, do several coats  with wet sanding in between. The usual procedure. My question is, if I am to use a wipe on poly without sanding sealing, wouldn’t it smear the dye even if the dye has been dried out? I know sanding sealer would lock it in but isn’t sanding sealer lacquer based? I always hear that poly should not cover lacquer because it would not allow the lacquer to gas off causing problems later down the road. Anyone have a clue. Is it ok to coat poly over sanding sealer/lacquer?


   
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Boo
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Posted by: @clinton

My question is, if I am to use a wipe on poly without sanding sealing, wouldn’t it smear the dye even if the dye has been dried out? I know sanding sealer would lock it in but isn’t sanding sealer lacquer based? I always hear that poly should not cover lacquer because it would not allow the lacquer to gas off causing problems later down the road. Anyone have a clue. Is it ok to coat poly over sanding sealer/lacquer?

@clinton My short answer is, I don’t know. 

However, I would imagine it will be ok to use sanding sealer and so long as it’s dry and cured fully for a few days, it should be ok to sand and use wipe-on poly over the top. I think what I would do is all the usual stuff and then spray some mist coats of sealer on. When dry and cured, give it all a light sanding, being careful not to rub through. Clean it off to get rid of any dust. 
Then, wipe on a light coat of poly, don’t press on to hard, and let it dry. Rub down lightly with wire wool, clean off again and add another coat. Repeat that process again. Then you should be safe to build up more layers of poly. 

That would be my approach but I would do some testing on scrap first. 

I have asked this question to someone else who will know and I am waiting for a reply. I’ll let you know as soon as he has got back to me. 👍

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Rocknroller912
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@clinton

Not all sanding sealers are cellulose based. Acrylic such as Chesnut brand is compatible with most things. Not sure if it’s available where you live. Probably would not use it on an acoustic as it’s quite stiff but works well on solid boards.

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mark bailey
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There's only one way to find out! I think y'all probly know my answer - I'm with @Boo :

Test on scrap...let us know how it goes! ... sorry can't help more... 🤔 

Measure twice, cut once...


   
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Clinton
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@boo thanks boo. Thinking the same thing. I think if I am wrong damage happens within years. That is why I wanted to confirm a definitive approach but practicing on scrap is on my radar. What do you think @markbailey. Perhaps Louis might know.


   
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Boo
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Posted by: @clinton

Perhaps Louis might know.

@clinton Is Lewis on this forum? He must be, surely. Maybe @markbailey can give him a nudge for a little input perhaps. 😉 I suspect he would say the same thing though, test on scrap. 😆🙌

Make guitars, not war 🌍✌️🎸


   
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mark bailey
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@boo I'm sorry to report that our Lewis has moved on to better things... 😪 I'm sure you have all learned by now that guitarmaking is not the best way to make money...he had an offer he couldn't refuse so what can you do? We are sad but extremely grateful for all him and his dad done for us and wish him the best best of luck. 👍 He has promised to not be a stranger so I'll tell him you was all asking ....

Measure twice, cut once...


   
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Russ
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Posted by: @markbailey

@boo I'm sorry to report that our Lewis has moved on to better things... 😪 I'm sure you have all learned by now that guitarmaking is not the best way to make money...he had an offer he couldn't refuse so what can you do? We are sad but extremely grateful for all him and his dad done for us and wish him the best best of luck. 👍 He has promised to not be a stranger so I'll tell him you was all asking ..

Wishing him all the best Mark @markbailey. Maybe when @boo makes the move to Scotland he could be your new spray guy. 🎨😁🤔🖌️

 

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mark bailey
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Cheers @russ I'll pass that on... Finishing is one of the most challenging and rewarding parts of the job - good to get my hands back on the ole spray gun... 

Measure twice, cut once...


   
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Boo
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Posted by: @markbailey

I'm sorry to report that our Lewis has moved on to better things... 😪 I'm sure you have all learned by now that guitarmaking is not the best way to make money...he had an offer he couldn't refuse so what can you do? We are sad but extremely grateful for all him and his dad done for us and wish him the best best of luck. 👍 He has promised to not be a stranger so I'll tell him you was all asking ....

@markbailey Oh no! Sorry to hear that. I’m sure you will enjoy playing with your spray guns again Mark. I can come and help on occasions if needed. 

I was looking forward to meeting Lewis and everyone else at the Bailey workshop but I wish him all the best in his future endeavours. If you read this Lewis, good luck for the future and definitely don’t be a stranger. 

Exciting times for Scotland. 🏴󠁧󠁢󠁳󠁣󠁴󠁿

Make guitars, not war 🌍✌️🎸


   
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Russ
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Posted by: @markbailey

Cheers @russ I'll pass that on... Finishing is one of the most challenging and rewarding parts of the job - good to get my hands back on the ole spray gun..

@markbailey.

Great to hear that you're back at it Mark and the passion is still running strong. ✊✌️

🙏🎶🎸🙂

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Bill Flude
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Sad to hear that Lewis is moving on - he did a lovely job on my Tele - please send him my best wishes.

Measure once........
Measure again.........
Sod it - make tea!


   
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Boo
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@clinton How did you get on with this? How did it turn out? 

After moving house and country, I’ve not had much chance to engage in this forum so I’m not up to speed with everything. 

I finally have an internet connection again so I’ll be here a bit more now. I’m still a long way from building any guitars for a while though. ☹️

Make guitars, not war 🌍✌️🎸


   
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Clinton
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@boo I have several builds that I intend to complete before the years end all with no finish. Trying to attempt a different lacquerless approach. Will be back at it again real soon. Did some scrap test pieces and time checking results. Seems to fair well, looks great even after buffing. Not sure however if I like it more than lacquer. Just different feel and look.


   
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