Advice on doing a 2Pac Finish

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Originally Posted by Tegmark

As I understand there isn't much difference between 7008 to 2pack polyu in the auto trade. I bet it could be thinned down & sprayed no problems with a good setup. If there is explosive risk with spraying, it would be the same for diy spray painters in their garage id imagine.

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Tegmark

I really think you should read the MSDS for 7008. Perhaps the reason Valspar say "don't spray" is that one of 7008's components or atomised 7008 is a carcinogen?

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Originally Posted by ian

Tegmark

I really think you should read the MSDS for 7008. Perhaps the reason Valspar say "don't spray" is that one of 7008's components or atomised 7008 is a carcinogen?

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Your assuming I haven't read it. I'm aware of the carcinogen threat. I have a respirator, googles for doing it by brush in a unopened area. And if I was ever gonna spray it, I would have a setup like a spray painters garage.

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Originally Posted by Tegmark

I'm reading about sellys araldite epoxy glue. Might try that & hope its as transparent as my clear method.

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I've had mixed results doing this. The worst being when I put it in a crack with a charred edge and the glue dripped over the high points and formed air gaps that were lighter than the char, which looked terrible. The best being when I used acetone to clean the area first with a ground down toothbrush (only one bristle tree wide) and once dry and vented, I overfilled the gap substantially and then vibrated it with a orbital sander until the glue gelled (5 - 10 mins). The trick with this is letting the glue set for the stated time so that it fully cures and shrinks before you cut it back and sand it. As with all epoxy it is still pretty gummy under the sand paper though. If you want it clear, get the ultra clear product.

I've also used epoxy resin and araldite with wood flour to make a filler paste. My tip for this is to use a very sharp blade to trim it down within about 30 minutes of setting. Otherwise it is too hard to cut down without damaging the surrounding area.

I hope that saves you some time and sanding.

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Originally Posted by SPF

If you want it clear, get the ultra clear product.

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Araldite® Ultra Clear | Selleys Australia

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Originally Posted by SPF

I've had mixed results doing this. The worst being when I put it in a crack with a charred edge and the glue dripped over the high points and formed air gaps that were lighter than the char, which looked terrible. The best being when I used acetone to clean the area first with a ground down toothbrush (only one bristle tree wide) and once dry and vented, I overfilled the gap substantially and then vibrated it with a orbital sander until the glue gelled (5 - 10 mins). The trick with this is letting the glue set for the stated time so that it fully cures and shrinks before you cut it back and sand it. As with all epoxy it is still pretty gummy under the sand paper though. If you want it clear, get the ultra clear product.

I've also used epoxy resin and araldite with wood flour to make a filler paste. My tip for this is to use a very sharp blade to trim it down within about 30 minutes of setting. Otherwise it is too hard to cut down without damaging the surrounding area.

I hope that saves you some time and sanding.

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Thanks SPF.

I'm trying epoxy now, and its difficult but quick compared to filling up the gaps with the clear it self which takes many fills. But I think the clear is more see thru. I read about the brand Artresin is one epoxy that doesn't yellow over time, so ill try it when I can.

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Originally Posted by Tegmark

Thanks SPF.

I'm trying epoxy now, and its difficult but quick compared to filling up the gaps with the clear it self which takes many fills. But I think the clear is more see thru. I read about the brand Artresin is one epoxy that doesn't yellow over time, so ill try it when I can.

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The other thing that I have been meaning to try for years is optically clear casting resin. Here are some examples:
Polyurethane Casting Resins | Dalchem
Easycast Clear Resin

There are also equivalent epoxies:
Solid Solutions - Casting Resins

These products are used for potting electronics, making castings, and filling behind glass for some specific applications. As with acrylic resins, they can suffer from air bubbles rising up through them if you have not wet the substrate they are poured into and over.

All told, these will be expensive ways to get the clear fill, but once you have worked out the way to use them, they will be bullet proof. If you decide to try any of them I'd like to see your results. I've used these for casting and electronics, but not on timber.

Quote:

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Originally Posted by Tegmark

Thanks SPF.

I'm trying epoxy now, and its difficult but quick compared to filling up the gaps with the clear it self which takes many fills. But I think the clear is more see thru. I read about the brand Artresin is one epoxy that doesn't yellow over time, so ill try it when I can.

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The other thing that I have been meaning to try for years is optically clear casting resin. Here are some examples:
Polyurethane Casting Resins | Dalchem
Easycast Clear Resin

There are also equivalent epoxies:
Solid Solutions - Casting Resins

These products are used for potting electronics, making castings, and filling behind glass for some specific applications. As with acrylic resins, they can suffer from air bubbles rising up through them if you have not wet the substrate they are poured into and over.

All told, these will be expensive ways to get the clear fill, but once you have worked out the way to use them, they will be bullet proof. If you decide to try any of them I'd like to see your results. I've used these for casting and electronics, but not on timber.

Quote:

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Originally Posted by SPF

The other thing that I have been meaning to try for years is optically clear casting resin. Here are some examples:
Polyurethane Casting Resins | Dalchem
Easycast Clear Resin

There are also equivalent epoxies:
Solid Solutions - Casting Resins

These products are used for potting electronics, making castings, and filling behind glass for some specific applications. As with acrylic resins, they can suffer from air bubbles rising up through them if you have not wet the substrate they are poured into and over.

All told, these will be expensive ways to get the clear fill, but once you have worked out the way to use them, they will be bullet proof. If you decide to try any of them I'd like to see your results. I've used these for casting and electronics, but not on timber.

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Thanks. I tried epoxy resin & it was not good tbh. It always creates small air bubbles & is very hard to sand. Not as clear & see thru as the poly clear itself.

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Originally Posted by Tegmark

Thanks. I tried epoxy resin & it was not good tbh. It always creates small air bubbles & is very hard to sand. Not as clear & see thru as the poly clear itself.

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If you are going to use Epoxy, sanding it back is horrible, its gummy when its not fully cured and very tough when it is. If you understand how much it will shrink in a given situation, the better option is to overfill it let it start to gel and then trim it back with a very sharp blade as far as you can. To set your trim height, you can use tape for cutting it back to within 0.15 - 0.25 mm or paper or card tacked down for anything thicker. You simply put the tape down along two edges and run the blade through the glue while the elevation is set bythe tape.

A cheap easy blade to use for this is a disposable box cutter blade glued onto a piece of timber to ensure it stays flat. Make sure the blade sits out at least 4 mm from the leading edge of the timber.

If you want a more permanent solution, you can also modify a plane (good reuse of a cheapy) or spoke shave to do this job. Or you can clamp a plane between two blocks of timber, with the plane set the correct elevation above the glue. If you are going to try a plane for this job, make sure you lubricate the blade so that it doesn't jam as you try to trim the glue back. Use a lubricant that can be easily cleaned off the glue (and timber) later. I use paraffin wax rubbed onto the blade as it lubricates the blade but generally doesn't get onto the parent material.

The other thing to mention is that pushing any blade through epoxy perpendicular to travel is difficult. If you have an approach angle of 35-50 degrees, I find that works well. You may still have to use a slight sawing action but it should take almost no effort.

I hope that helps.

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Originally Posted by SPF

If you are going to use Epoxy, sanding it back is horrible, its gummy when its not fully cured and very tough when it is. If you understand how much it will shrink in a given situation, the better option is to overfill it let it start to gel and then trim it back with a very sharp blade as far as you can. To set your trim height, you can use tape for cutting it back to within 0.15 - 0.25 mm or paper or card tacked down for anything thicker. You simply put the tape down along two edges and run the blade through the glue while the elevation is set bythe tape.

A cheap easy blade to use for this is a disposable box cutter blade glued onto a piece of timber to ensure it stays flat. Make sure the blade sits out at least 4 mm from the leading edge of the timber.

If you want a more permanent solution, you can also modify a plane (good reuse of a cheapy) or spoke shave to do this job. Or you can clamp a plane between two blocks of timber, with the plane set the correct elevation above the glue. If you are going to try a plane for this job, make sure you lubricate the blade so that it doesn't jam as you try to trim the glue back. Use a lubricant that can be easily cleaned off the glue (and timber) later. I use paraffin wax rubbed onto the blade as it lubricates the blade but generally doesn't get onto the parent material.

The other thing to mention is that pushing any blade through epoxy perpendicular to travel is difficult. If you have an approach angle of 35-50 degrees, I find that works well. You may still have to use a slight sawing action but it should take almost no effort.

I hope that helps.

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Thanks good info there. I will experiment. In the meantime while I wait for some stuff to arrive I thought about my plan to get polyu to a high gloss. This is my basic plan.

Hand polish method: Finish with the finest grit sand paper, atm I have 5000grit but heard about up to 12000. Then compound & polish with foam pads. To me hand method is the most important as wood usually is too delicate for any machine work. Since there are sharp edges that wool will cut thru straight away, curved edges etc that a machine will have a high chance of cutting thru.

Machine method: Cut with a rotary buffer w/ double sided wool pad & also swansdown mop. Then use a d/a polisher with cutting & polishing foam pads. More suited for open large areas like a table top. I found the rotary has so much more cut power than a mop on a drill that you really need heaps of experience to use without damaging the clear.

Machine & Hand method: Cut with wool to save alot of time & polish up with hand foam pads. I did this with oil based polyu & it took a while being tough.

Tegmark I look forward to seeing the results.

If you are going to use 2000 grit plus paper make sure you wipe the surface clean between each grade of paper and tack cloth it. It is a real pain if you pick up a loose 1000 grit when using 5000 or higher and it ruining all your work.

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Originally Posted by SPF

Tegmark I look forward to seeing the results.

If you are going to use 2000 grit plus paper make sure you wipe the surface clean between each grade of paper and tack cloth it. It is a real pain if you pick up a loose 1000 grit when using 5000 or higher and it ruining all your work.

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Thanks. I think finishing off with 5000grit looks pretty good, 50/50 matte/gloss.

From all the testing I have done in past few weeks:
- Cheapo brushes are not worth it. My purdy ox hair gives less pinholes than the cheapos. However, thin cheapo does a decent job with very thick coats as you have plenty of film to sand and this brush requires very small acetone to clean.
- There seems to be no reason why a varnish brush gets thrown out after the job, after a dozen or so uses my ox hair seems as good as it was when new.
- Whether coats were very thick, thin, or thinned by 10%. they all bulged up right near edge of wood.
- I found it utterly impossible to work with thin coats as they simply are not thick enough to rub out the pinholes and bulges near edge of wood without causing witness lines and rubbing into stain.
- Unless the surface of wood is perfect like blocked out high build primer and your spraying 3-4 thin coats, the only way i finished a test piece was 5-6 thick coats, thick enough if vertically would result in major runs.
- Visually there doesn't seem to be much diff at all between 3-4 thin coats vs 5-6 very thick. except the latter has a bit more depth perhaps.
- Even if you brush it on like glass without a visual flaw, 30-60mins later pinholes appear probably from the chemical reactions.
- For reasons I don't know, there is always a slight ripply reflection with say a light source while moving against the grain as appose to moving with it. This happens with off the brush, sanded to 5000grit or polished up. whether coats are thick, thin or not brushed. I'm not really sure if this is the grain causing this like an optical effect or just something that plastic poly does? I will try shellac & lacquer one day to see.

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Originally Posted by Tegmark

From all the testing I have done in past few weeks:
- For reasons I don't know, there is always a slight ripply reflection with say a light source while moving against the grain as appose to moving with it. This happens with off the brush, sanded to 5000grit or polished up. whether coats are thick, thin or not brushed. I'm not really sure if this is the grain causing this like an optical effect or just something that plastic poly does? I will try shellac & lacquer one day to see.

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Was this on the same timber (as per previous post in this thread https://www.woodworkforums.com/f9/can...roperly-207490) or something different? How fine did you sand prior and did you use any grain filler?

When I have used it on Teak, Meranti, and another unidentified furniture timber (that I think was poorly cut silky oak), I got the exact same result. It didn't matter how many coats, there was still evidence of grain. In each case it was wet sanded in between coats. I measured it (because I could at the time) and the depth averaged out at about 0.1mm after 3 coats. To be honest, on the pieces of furniture it doesn't bother me because there are no broad flat surfaces. On the meranti window sills it still irritates me when I clean them, but then 15 minutes later it has a layer of salt on it and I can't tell anymore.

On harder timber I haven't found it to be so much of an issue.

BTW thanks for posting up your results above.