Pore fill question

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shane77
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Pore fill question

Post by shane77 » Tue Mar 07, 2023 9:54 am

I'm currently finishing a blackwood acoustic body... after pore-filling with Zpoxy (2 coats) and then shooting a few coats of lacquer (Mirotone 3220), I realised my pore-filling attempts were not great...I still have pinholing in areas.
I've never used the Zpoxy before so I may have sanded off too much. Is it possible to redo another Zpoxy coat over the top of the lacquer, before adding more coats, or am I stuck with my substandard efforts?

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kiwigeo
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Re: Pore fill question

Post by kiwigeo » Tue Mar 07, 2023 10:52 am

The first thing you need to decide when using epoxy as a pore filler is whether to aim to fill just the pores (ie sanding back area between pores to bare wood) or to finish up with an even layer of epoxy over the entire surface. I opt for the former when using epoxy.

I know Z poxy can be used over shellac..not sure about lacquer. I suggest you get a piece of scrap blackwood and pore fill, spray lacquer and then apply some more Z poxy.

I used to use Zpoxy but have moved to using Boatcote epoxy with their special thinner added to the mix.
shane77 wrote:
Tue Mar 07, 2023 9:54 am
I'm currently finishing a blackwood acoustic body... after pore-filling with Zpoxy (2 coats) and then shooting a few coats of lacquer (Mirotone 3220), I realised my pore-filling attempts were not great...I still have pinholing in areas.
I've never used the Zpoxy before so I may have sanded off too much. Is it possible to redo another Zpoxy coat over the top of the lacquer, before adding more coats, or am I stuck with my substandard efforts?
Martin

shane77
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Re: Pore fill question

Post by shane77 » Tue Mar 07, 2023 11:34 am

Thanks- agree testing would be safest...
I used option 1, and sanded back to bare wood leaving only filler in the pores. I ended up pulling out too much while trying to sand across the grain (to avoid pulling out the filler), but that only resulted in more scratches for me, so I'm not sure what the technique should be?

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kiwigeo
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Re: Pore fill question

Post by kiwigeo » Tue Mar 07, 2023 12:59 pm

I've not had many issues pulling out epoxy from the pores during sanding. I usually end up doing more than 1-2 epoxy sessions though...usually at least 4 for most of my builds.

As noted I tried Zpoxy and also West Systems but now use Boatcote epoxy.
shane77 wrote:
Tue Mar 07, 2023 11:34 am
Thanks- agree testing would be safest...
I used option 1, and sanded back to bare wood leaving only filler in the pores. I ended up pulling out too much while trying to sand across the grain (to avoid pulling out the filler), but that only resulted in more scratches for me, so I'm not sure what the technique should be?
Martin

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WJ Guitars
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Re: Pore fill question

Post by WJ Guitars » Tue Mar 07, 2023 4:31 pm

I also use 'Boatcote' epoxy and generally have found that three coats works the best. This involves sanding carefully back after each coat to fill the pores. It takes longer to complete the pore filling to achieve a levelled surface, however, it is worth the time spent to achieve a better finish.

Wayne

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Re: Pore fill question

Post by asgilbert » Thu Mar 09, 2023 3:36 pm

Hi Shane, I made a rookie mistake and did not use a firm backing while sanding and had very poor results. Since changing to a firm backing while sanding things have gone much better. I use west systems diluted 30% for first coat so it soaks in and then 2 coats sanded back to wood in between.

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kiwigeo
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Re: Pore fill question

Post by kiwigeo » Thu Mar 09, 2023 3:43 pm

If you're using West Systems then make sure you're using the 207 non blooming hardener.
asgilbert wrote:
Thu Mar 09, 2023 3:36 pm
Hi Shane, I made a rookie mistake and did not use a firm backing while sanding and had very poor results. Since changing to a firm backing while sanding things have gone much better. I use west systems diluted 30% for first coat so it soaks in and then 2 coats sanded back to wood in between.
Martin

AKEric
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Re: Pore fill question

Post by AKEric » Fri Mar 10, 2023 2:56 am

Thanks for your input Martin,

I have tried a few different epoxy pour fill products with varying results. I'm always ready to try something new. I looked at the TotalBoat website and saw many epoxy options. Which one do you recommend?

And is it the Epoxy Primer Thinner 200 you use to thin the epoxy?

Thanks for your help.

Eric

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Re: Pore fill question

Post by Mr K » Fri Mar 10, 2023 3:58 pm

Well I have used many brands of epoxy over the years, boats etc and yes got all the allergies.
As for pore filling and I am not an acoustic builder so you may take this with a grain of salt :)
The best I've used for full setting in thin layers is the West with the 207 hardener, it's flows better than the bote coat , is clearer and in my findings sets to a more sandable finish quicker. The only problem I have had is with fish eyes with one batch I had and it wasn't only me. My latest batch is perfect.

Bote cote is fine but I find I have to really mix it very well and warm it up to make it mix and flow better( I'm in Victoria) if I don't do this the setting is a bit inconsistent. I also find that it is cloudy and not clear like the West.

Z-poxy ok, the trouble I've had with this is also inconsistent set, and the odd thing that happened was swelling of the resin in the pores over time as it absorbed the solvents from the nitro with time, as it was my own guitar I ended up refinishing it about a year after the initial build

Method, and this follows up on Martins post where he suggests two methods, I've tried both and have settled on using the West with a 1" brush putting a little on at a time and brushing out as thin as possible, Sanding just back to wood after a few days and repeat three or four coats you should end up with a very thin layer of epoxy as a perfect base for spraying.

Worth noting that it takes Epoxy seven days to fully cure.

And regarding your question thinners for epoxy primer, this is a completely different product and do not use it with your resin.
Cheers Mark

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Re: Pore fill question

Post by kiwigeo » Fri Mar 10, 2023 6:26 pm

For Zpoxy I used to use meths to dilute the resin a bit. For Boactcote I use their standard resin and hardener and I mix in their TPRDA Preservative and reactive Dilutent....it reduces viscosity and surface tension of the mix
AKEric wrote:
Fri Mar 10, 2023 2:56 am
Thanks for your input Martin,

I have tried a few different epoxy pour fill products with varying results. I'm always ready to try something new. I looked at the TotalBoat website and saw many epoxy options. Which one do you recommend?

And is it the Epoxy Primer Thinner 200 you use to thin the epoxy?

Thanks for your help.

Eric
Martin

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Allen
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Re: Pore fill question

Post by Allen » Sat Mar 11, 2023 6:47 am

I switched to BoteCote epoxy with no-yellowing hardner years ago. Always add their TPRDA thinning additive. Living in Cairns it is dead easy to mix and is very thin going on even in what you could call our "Winter". Always gets 3 sessions for all timbers and 4 for the odd one that has enormous pores.

Overnight cure always before sand back and re-apply
Allen R. McFarlen
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yakka
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Re: Pore fill question

Post by yakka » Fri Mar 24, 2023 11:05 am


gtrboy77
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Re: Pore fill question

Post by gtrboy77 » Thu Apr 06, 2023 6:35 am

I thought I read somewhere (might have been on here) that you can use egg whites as pore filler. It sounds kind of crazy, but I guess if you’re going to finish over top of it, it might actually work. Anyone on here try that method?

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kiwigeo
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Re: Pore fill question

Post by kiwigeo » Thu Apr 06, 2023 9:13 am

Using egg whites as a pore filler is an old technique. It works but like any method there are pros and cons. I did a test pore fill on some rosewood back sets using egg white, epoxy and aqua coat.

Egg white method - no nasty chemicals and ingredients are cheap. Sink back an issue. Method - brush on a couple of coats of egg whites and let dry. My method - Work up a sludge with 320 grit wet and dry paper and a bit of water and work into the pores. Let dry and lightly sand. Repeat 2-3 times.
Epoxy - messy and hazardous. 2-3 sessions gives a good pore fill with no sink back.
Aquacoat - low hazard filler. Needs alot of sessions to get a decent fill. Some of the filler gets pulled out during french polishing process. Ive been using this of late but am not 100% happy with it and will go back to epoxy.


gtrboy77 wrote:
Thu Apr 06, 2023 6:35 am
I thought I read somewhere (might have been on here) that you can use egg whites as pore filler. It sounds kind of crazy, but I guess if you’re going to finish over top of it, it might actually work. Anyone on here try that method?
Martin

gtrboy77
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Re: Pore fill question

Post by gtrboy77 » Thu Apr 06, 2023 9:58 am

Thanks for the info on the egg whites as filler. I’ll still give it a go sometime. Yeah, I’ve used aqua coat and it does require a ton of sessions. I wasn’t a big fan of it. Dang guy that sold it to me at the woodworking store made it sound like it was the greatest thing since sliced bread.

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kiwigeo
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Re: Pore fill question

Post by kiwigeo » Thu Apr 06, 2023 1:29 pm

I saw a few comments about the alcohol used in French Polishing causing the stuff to get pulled out of the pores...not sure if that is the problem.



gtrboy77 wrote:
Thu Apr 06, 2023 9:58 am
Thanks for the info on the egg whites as filler. I’ll still give it a go sometime. Yeah, I’ve used aqua coat and it does require a ton of sessions. I wasn’t a big fan of it. Dang guy that sold it to me at the woodworking store made it sound like it was the greatest thing since sliced bread.
Martin

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Taffy Evans
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Re: Pore fill question

Post by Taffy Evans » Thu Apr 06, 2023 2:53 pm

Hi, I tried mixing up a sludge of wood dust [very fine from sanding the endgrain] and shellac, and working it into the pores. Worked ok, but I lost my sample piece so I'll try again.
Taff
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gtrboy77
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Re: Pore fill question

Post by gtrboy77 » Fri Apr 07, 2023 2:33 am

Has anyone ever used hide glue as pore filler? I know it’s probably a crazy idea, but the stuff sticks to everything. If you put it on that then used a plastic scraper to scrape it flush, it would minimize scraping later. Just an idea…

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Allen
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Re: Pore fill question

Post by Allen » Fri Apr 07, 2023 5:55 am

Absolutely every thing you could think of has been tried as a pore filler. And I have tried a fair number of them. Nothing new under the sun.

It comes down to what you want to accomplish, how much time you are willing to devote to it, and what are your expectations such as clarity, sink back or moving with humidity.

Epoxy is the only one that ticks those boxes for me. However not all epoxies are created equal, so finding one that is available to you is sometimes a challenge.
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TallDad71
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Re: Pore fill question

Post by TallDad71 » Fri Apr 07, 2023 7:30 am

I’ve been using this for the last two years and have found it to be very reliable.
Very easy to apply, very easy to sand back.

Epoxy is bomb proof but just too much like hard work for me.

That said I never use cellulose for a finish, I mainly go for waterborne products.

Aqua Coat Clear Wood Grain Filler Pt. by Aqua Coat https://amzn.eu/d/6EOztgs
Alan
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onlytendola
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Re: Pore fill question

Post by onlytendola » Thu Jun 08, 2023 8:58 am

I hope this isn't hijacking this thread, but I've got a question about WHEN and how to porefill... I've recently started staining my instruments using stewmac's colortone stains to do rubbed bursts. It's fine on tops and backs that don't have open pores (NZ beech for backs usually) but my most recent instrument is built with blackwood, so the pores really should have been filled. However I wasn't sure when to do it so I didn't seal the wood and end up just pushing stain around over the surface. I use CA to wick in and glue my bindings and I seal the channels with shellac first to try to keep everything tidy. But anywhere with any shellac or CA takes stain very poorly, and I don't want to have that problem across the whole back. I assume epoxy with have a similar effect, and I've used egg white/sawdust in the past but I'm guessing that water-based stain over the top of that will turn that into some kind of meringue.
The internet is full of tutes on staining, and tutes on porefilling, but I don't know how to bring these together successfully. If any of you are doing this I'd love to hear your methods!
Cheers,
Davy

asgilbert
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Re: Pore fill question

Post by asgilbert » Wed Jun 14, 2023 7:02 pm

Hi Davy, Saw this some time back from Stewmac. They cover Pore filling in this video its about 28mins in.
https://www.youtube.com/watch?v=ntsiNsa ... 1jq3HeGgCv

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