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Nitro over Poly?


yorks5stringer
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I have a Sunburst Poly finish body that I am going to paint Lake Placid Blue with Nitro. I've scuffed the poly with 400 grade w&d. Do I need to shoot a coat of primer  over first before doing the Blue Nitro? I'm pretty sure the Nitro will adhere, its more about the Blue colour covering over the Sunburst: should I just keep going with coats until I get a nice solid Blue? I've got clear lacquer to go over after the colour coat too.

I have got a can of Primer also so it's no problem doing it, but don't want to add extra complexity if not necessary

Thanks

Edited by yorks5stringer
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I like lacquer it will adhere fine to the poly since poly is catalyzed meaning it dries by chemical reaction and when dry top coats can't eat into it. Lacquer however can not have poly applied over the top.

I have a custom shop I do this kind of thing in. I would shoot it with primer and level sand any scratches etc with the primer. If you are using lacquer the 400 grit scratches will show in the lacquer. No matter how many things you read that they may not believe me you are better off with 600-800 grit before puttting on your top coat. If you clear over it you can do that as soon as the base color sets. It can be done a bit later as well. 

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Replies crossed, no imperfections, it's a new Bass that I have taken apart ready for Spraying.  Using Rattle Cans with a handle and proper mask. Another question I had to reshape the headstock from Harley Benton shape to Fender shape. This meant losing some of the original clear coat on the headstock where I re-shaped and where the decal was. I'm thinking shooting a couple of coats of the clear Nitro first just to seal it before going onto the Amber Tint as i don't have any clear primer?

Edited by yorks5stringer
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This is how it started out!!

Yes you should clear over it first or the amber time will soak into the wood and show. Also bare wood will pull on your paint. You will see a line no matter what you do with it unless it is sealed over. The clear is what is used on guitars that show wood tone as the sealer. You can buy the expensive sealer or use the nitro clear to seal it with. 

Then you apply the toner on top of that and you will need to clear over the whole thing once the toner is on to protect it. The toner will lose it luster fast if you don't clear over it. 

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Great, good to know. So to recap:

Scuff coat again over body and neck with 600-800 grit w&d

Shoot a couple of coats of clear gloss over headstock, then shoot Amber Tint coats, then finish with clear Gloss.

Don't bother putting primer on body ( as covered in good quality poly, no imperfections) and shoot coats of LPB followed by clear Gloss.

 

Obviously will observe timing between coats and leave things to dry a couple of week before final polishing

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Yes you have it all correct. Post pics when you are finished. 

Nothing like walking into a pawn shop and finding a great guitar for $60. Yeah it needs finishing but that I can do nicely myself. I bought a Fender Strat for $65. It had been played and it was full of scratches etc. 

I had the materials here to refinish it. It was red. I hate bright red on anything. I used a heat gun to strip it. The poly finish comes right off in chunks with a little heat. Since it was going to be 3 color sunburst the wood needed to be sealed with clear. I put like 5 coats of clear on it and used the clear to level the body. I used 1200 as the last before coloring it. I put down the amber in the center with more coats of it around the edges to give it that orange cast. Then I shot black free hand around the edges. I put like 10-12 coats of clear over it all then buffed it out. I finished the neck with high shine gloss. The fret board was rosewood so I finished it with tung oil after using 1000 steel wool to polish the fret and clean the fret board. I changed out the electronics to better quality and added into it a push pull volume pot so it could have the bridge pickup and neck pickup togehter. I added a push pull pot on the tone control so the tone could use both  the .22 microfarad or a .47 microfarad capacitors for changing the tone. I got rid of the two volume thing so the master volume handled the guitar. In the other control I put in a cut control so as you turn down the volume you can keep the bright side of the tone. When it was done a guy that plays in a local band wanted it so bad he was offering me $1000 for it because of it's custom everything. I let him have it for 800. I had roughly $250 in it with the parts and paints and original cost. 

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I'd be tempted to use 600 grit aluminium oxide (a.k.a. sterated aluminium) rather than wet and dry. The wet and dry can shed some abrasive which then leaves little black bits embedded in the finish. Also you probably won't want to use it wet anyway - that will lift the lacquer on any edges

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Weird how advice differs on what grade to scuff with. I originally read someone say 200 grit, then later 400 which I went for. Harley  above suggests 600-800 as does Norris.

Certainly I could see the scratches even though I went over with 600 grade. Hopefully as I'm going over poly the edges will be fine.

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You only need to key the surface. Anything coarser than 600 grit will show scratches that you then need to build up the nitro to fill. 600 is ideal for flatting off between too. Give it two or three light coats at least 30 minutes apart and then leave it 24 hours before flatting before applying the next set of coats. When you get the last coat on leave it for 4 to 6 weeks before flatting and buffing

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Another example of not to believe what you see on Youtube....I watched a demo of a well-known NW Company spraying a guitar body with 3/4 coats of nitro and then saying he would do a further 2 coats of clear gloss.

So I decided I was going to do the same: 3/4 coats colour and 2 clear, let it dry and then flat and buff. However I noticed this morning that I could still see the scratches through the paint from my scuff coat, so based on Norris's message above decided to flat off 'in between'. Did that very gently and then shot a couple more colour coats and hey presto, no more visible scratches from my initial scuff coat through the nitro paint! Thanks!

So tomorrow will do 2 coats of clear gloss and then hang it up till the New Year! Have been Amber Tinting the neck too, got a run which I only saw this morning from last night, so rubbed it down with 1200 and then shot a couple more coats over that now bare area, let it dry then continued with front and back of the neck and its healed in nicely with no trace of the run. Thought it best to do it early on rather than build up layers over it which will just have to be rubbed back down.

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Not 100% I'm sure how many coats you have currently put on, but it doesn't sound like much. Your best bet is to follow the rule of three. This is 3 passes to each coat, 3 coats per day, 3 days of spraying. You will definitely have enough lacquer to level then. If you're not careful and have sprayed too little you'll wait a month then burn through and have to start all over again.

As for the differing advice, that's quite common with finishing. What works for one person may not for someone else as a great deal of the details can vary from person to person...for example how heavy you're spraying, what the conditions are like, what abrasive paper you're using etc etc!

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That'd be safer in the long run, if it's an aerosol you'll want to use at least the whole can of clear, but exactly how much finish you need on the bass depends on how heavy your coats are,  how even they are and of course what your desired end result is. If you have a textured orange peel like surface you'll need to remove more finish when it comes to wetsand and buff. Also keep in mind that if you're using an aerosol they don't have very high solid content, so most of what you're spraying will be thinners which will evaporate. So more lacquer is generally better, you'd have to be really laying it on thick and use multiple cans of clear to end up with a thick finish with aerosol Nitro.

Edited by Manton Customs
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Thanks for that. So use a whole can of colour and ditto of clear? Does one need to flat the colour before putting on the clear or will the clear 'melt' into colour coats?

Also, I've put on 7 coats of Amber onto the neck. I have a new decal (cough!); do I need to flat where the decal will go before  building up the coating with clear and then flatting to remove the 'edge'?

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I was referring to the clear, sorry if it was misleading as you're still spraying colour coats! You can stop spraying colour when you're happy with how it looks, but a few extras can't hurt. Then 1 full can of clear following the rule of 3.

 You don't want to sand your colour coats unless really necessary, or you could get thin spots or burn through. The thinners in the clear Nitro will dissolve any roughness to the colour coats. Do your future level sanding of the clear coat (to remove dust knibs etc) in between clear coat sessions. 

For the neck you don't want to sand the tinted lacquer or you'll end up with an uneven tint, which can be difficult to even out. However the decal does need a good level surface. So spray a very good (level and glossy) final coat of tint. If you flatten it off and apply a decal over it you may also see scratches through the decal depending on the colour, so best avoided if possible.

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1 hour ago, Manton Customs said:

... Do your future level sanding of the clear coat (to remove dust knibs etc) in between clear coat sessions. ...

Something worth knowing is, to remove dust knibs in the lacquer, don't sand in the usual way. In stead of using the rough side of the W&D, turn the paper over and use the back. This will usually remove the knibs and you can often then avoid needing (yet) another coat. Besides, the next coat will bring yet more knibs anyway.

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5 hours ago, Grangur said:

Something worth knowing is, to remove dust knibs in the lacquer, don't sand in the usual way. In stead of using the rough side of the W&D, turn the paper over and use the back. This will usually remove the knibs and you can often then avoid needing (yet) another coat. Besides, the next coat will bring yet more knibs anyway.

Yep, depends how deep they are though, I use a tack cloth instead of the back of the paper to get the surfacey stuff. Tack cloths are another worthwhile addition... especially if you're ever spraying white! 

The level sanding is still important though to make sure you end up with a nice even finish. Best to level sand between every three or so coats and after giving the lacquer overnight to dry. Sand too soon and it'll ball up on you and create gouges in the finish.

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Had a bit of a disaster. I ran out of clear lacquer to finish off the body, it was covered with a full can of colour and looked rather nice. Rather than get it from my usual supplier (£12.99 a can plus £6 postage) I found another supplier who sold it for £10.99 delivered and it arrived the next day.

My former supplier did the cans with the nozzle loose, so you just inserted it and were ready to go. However this supplier had a safety seal under the nozzle which was pre-fitted and there were no warnings about it. So I shook the can, clipped on the handle and set about spraying noticing that it was a very poor spray. Inexperience made me continue in the hope the lacquer would melt into the paint but all I did was cover everything with orange peel and cos the spray was too fine, took the nozzle too close to the work. This melted some of the colour coat in places there are now areas of lighter colour than others. Hoping a further coat (after drying) would help (having now sorted the nozzle flow) I put it on this morning but the shaded areas are still showing.

I'm guessing leaving it to dry after virtually a full can of clear and rubbing smooth/buffing to get rid of orange peel/dust nibs isn't going to help with the shading and I need to start again with the colour coat?

Is it OK to shoot more colour over streaky colour/orange peel clear or should I rub it back to the old poly beneath or is there a middle ground? Also if I went with a different colour (lighter blue) would that be an issue?

Needless to say the suppliers of the can with the non-mentioned safety seal will not accept any responsibility......

 

 

 

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