Peelaway or Dry Ice Blasting?

[Herefordian]

Hi everyone

We have 3 large ceiling timbers with a lot of paint on we would like to clean up. They are C16-17. We have tried hand stripping but it us too difficult. Beams are in good condition and we have ruled out sand blasting - but whilst we were about to start using Peelaway but has just discovered dry ice blasting.

Has anyone any experience of this (on oak timbers) and can anyone offer advice?

Many thanks

Martin

 

[Penners]

I'm no expert and I have no experience of dry ice blasting, but I confess that the very word, "blasting", unsettles me. Paint clings to a surface, and if you remove it by blasting it, I worry that you are bound to remove some of the substrate too. Chemical stripping, however, changes the nature of the paint and releases its hold on the substrate, so it can be removed without causing any damage*.

I have seen sandblasted beams that have been completely wrecked (aesthetically, if not structurally) by the process. I imagine that dry ice blasting is less deleterious than sand, but I would still avoid it myself. I have had very good results with Klingstrip, and heard similar good reports of Peelaway.

* One rider to that statement - I have found that Klingstrip can cause the surface of softwood to become a little "fluffy", and to darken in colour. On hardwoods, however, I have found it excellent.

 

[88v8]

There is also plastic media blasting. Might widen your options.
Example here I have used, albeit not at all local.
http://www.blast-cleaning.co.uk/index.php?menuid=50&component=content&task=article&articleid=39&categoryid=9

Whatever medium is used, it crucially depends on the skill and care of the operator.

Ivor

PS welcome to the forum. If you edit your Profile to show your location it may assist in making recommendations, although I guess your nom de plume might gissaclue.

 

[Herefordian]

Thanks everyone (so far)!

Yes - a difficult one and I have heard lots of + and - reports. We have stripped all our timbers by hand, but these are just too tough, so trying to find an alternative!

Yes - location is a giveaway, but we're in rural North Herefordshire (Bromyard) if that helps!

Martin

 

[Flyfisher]

I'm no expert and I have no experience of dry ice blasting, but I confess that the very word, "blasting", unsettles me. Paint clings to a surface, and if you remove it by blasting it, I worry that you are bound to remove some of the substrate too. Chemical stripping, however, changes the nature of the paint and releases its hold on the substrate, so it can be removed without causing any damage.

That sums up my concerns about such processes. They seem to be excellent for applications where the old paintwork is to be replaced by some other covering and therefore have the dual benefit of paint removal and surface preparation, which is ideal for things like restoring old car bodywork and the like. Unfortunately, in many wood applications the challenge is precisely not to 'prepare' the underlying surface.

PPUK regulars will know that Middi knows a thing or two about working with oak and was open-minded enough to investigate the possibilities of dry ice blasting some time ago. His experience was discussed in this topic: http://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=12575. You'll have to ignore Fred Drift's digressions but the basic conclusions are disappointing, if not unsurprising.

Or, as someone once said . . .

 

[Toby Newell]

No.

To dry ice blasting.

A customer of mine which I have done many months of work over many years (who found me on here) got an ice blasting company in to remove the bitumen off of his reclaimed parquet blocks.

They charged him a ridiculous amount of money and badly damaged the blocks, I think the company was from Essex. I would therefore advise caution and maybe do not go with ice blasting.

I have been stripping wood for over 27 years (including the office of the deputy Prime Minister in The palace of Westminister) and have managed just fine without blasting of any sort.

http://www.floorsanding-uk.com/guide%20to%20wood%20stripping.html may be helpful.

PS I have stripped many hundreds of metres of beams, including for Rob Tavendale, it is a very, very hard and tiring job. Maybe go for the thixotropic peel away type stripper first to remove most of the paint and check carefully for any makers marks or warding marks with a strong torch as it would be a terrible shame to lose these if you are lucky enough to find any, then you can clean up (after neutralising) with scrapers and sanding by hand or a small sander with fine paper start with 80 grit and see how you go, it should leave few pigtails, then you can finish with 120 grit before finishing. Linbide and Bahco make the best Tungsten carbide scrapers, the blades are very expensive but because they are so sharp they can strip the surface clean whilst causing less damage via tearing out the grain than a cheaper hardened steel scraper or shave hook. Steel wire brushes will remove paint from the interstices but will open the grain, maybe try with a very stiff nylon brush whilst the stripper is still wet and active and finish off with a brass wire brush, which will still open the oak grain but will be more gentle.

The main idea after you have peeled away most of the thixotropic caustic stripper would be to use a solvent based stripper and keep it wet, with brass brush and/or stiff nylon brushes to remove most of the residue, basically anything sharp or brush like that you can think of may be useful, I have a whole tool box dedicated to 'stripping brushes' I have found a high powered pressurised steamer like from Karcher to be very helpful as the heat loosens any residue, it makes a lot of mess or course but gets the wood very, very clean, I used it on an oak panelled room and got the wood fantastically clean.

Toby

 

[88v8]

No.
To dry ice blasting.... ...finish off with a brass wire brush...... Toby

A classically full reply from Toby. I guess, harking back to the op, that whatever you do it will involve an element of just plain hard work. Hours, days, or weeks of careful graft. Which you pay for or do yourself. Some folk have the persistence, some don't. And that includes some tradesmen who like to pretend that there's a quick fix for everything.

Just a brief word about brass wire brushes. I wanted a small one for removing surplus lime pointing from a rough stone floor. I bought a few sets of small brushes which included one described as 'brass', but they were nothing of the sort. They were brass-plated steel.
So, any 'brass' brushes you buy, check with a magnet. Then whatever you're brushing, you won't destroy .

Ivor

 

[Penners]

It's also worth mentioning that ferrous wire brushes (or wool) are a bad idea on oak. The wood is acidic and can cause any particles of ferrous material left in its pores to rust. This can cause unsightly staining.

 

[Toby Newell]

Indeed.

Brassed brushes are very slightly better than plain steel ones the main advantage of pure brass brushes is not their resistance to corrosion but their softer nature.

It is fine to use steel wool on oak to strip, it is the perfect medium but only with solvent stripper and not a caustic water based one. Just make sure you clean up very well afterwards by vacuuming the timber. Using steel brushes is possible too but will damage friable parts more and leave iron marks. The marks are not such a problem on so old timbers as they will be quite dark apart frm the sapwood.

The pure brass brushes we always used (I still have mine from Parliament) were about five to six inches long and shaped like a shoe shine brush with a beech back. They are quite expensive. Maybe ask Jenkins in Tariff Road, Tottenham or Mylands. Ted Bundy has retired now but someone at Mylands may know.

Nylon is very durable and chemical resistant a good selection of pot scourers and floor scrubbing brushes are useful too.

 

[Penners]

It is fine to use steel wool on oak to strip....Just make sure you clean up very well afterwards by vacuuming the timber

And if you're not inclined to do the vacuuming really assiduously, avoid steel wool.

 

[Toby Newell]

Lol.

No. Really Penners. Steel wool is ok. I maybe used several hundred pounds of wool with several dozen gallons of DCM stripper on several miles of oak skirtings, dozens of doors, skirting, stairs, panels over 27 years. Steel wool is the best way togo, only way to go in fact, for a professional job.

I helped strip four committee rooms and several minister rooms inc deputy Prime Ministers at Palace of Westminister and dozrns of doors. Also at Law Society and many many other important listed buildings.

Steel wool is fine as long as you do not get it wet!

I remember a colleague stripping an oak floor and window cill in Chelsea and forgetting to close the window. Came back after the weekend (it had rained) to find iron stain measles! Out with the oxalic...

It really is ok Penners if you know what you are doing. Steel wool is much gentler than a brass brush as it doesnt open the grain. Just do not use it with water based strippers and clean well before water washing/staining (after stripping Penners we would after washing down with meths frequently wash with boiling soda then boiling oxalic acid solution to clean or apply a water stain so it is ok)

Maybe you have had a bad experience? To be honest, vacuuming was hardly never used, just a brass brush in the corners when wet (and during cleaning down with meths, then again when dry) and a Sandvik cabinet scraper and/or sharp stick to clean your quirks and liberal use of a dusting brush. Very rarely had a problem.

Steel wire brushes I have had much worse experiences with as I have found they tend to get micro abraded and can leave grey smears over the oak.

I would say, in my experience, it is fine to use steel wool with solvent based strippers but to heed Penners advice if you are using water based strippers like Peelaway or Klingstrip and always, always take your time to dry clean your quirks and corners! For example, as best as I recal, it took us all around one full day to strip one of the standard oak linenfold carved doors at the Palace of Westminister but maybe only half a day to stain, seal, apply three coats of satin shellac with a mop, colour out/even up rubber up and wire and wax, so the stripping, as usual on almost all jobs apart from full grain finishes, takes by far the longest time.

 

[Toby Newell]

Anyway...

Taking both Penners and my advice together, steel wool is fine as long as you ckean up and do not get it wet, when it can leave marks.

I can only go on experience. With beams I have only ever been asked to do half a dozen jobs or so, although that involved several hundred metres of beams in total! Personally I never used much stripper as far as I recal, preferring always mechanical means ie scraping and sanding. Stripper is not ideal on vertical surfaces especially above your head and old beams are irregular and have many holes which are hard to clean.

I do not think many people are crazy enough to strip old beams by hand so there is no precedent really. I still think scraping and sanding is the way to go but really it is trial and error to find which way suits you best as it is very hard (and messy) work.

I dislike the act of stripping beams very much but then the colour and smoothness of a several hundred year old oak or elm beam is incomparable.

And please do check for warding, makers or fixing marks, Rob had some on his hearth beam and I was able to sand round them.

 

[Delta]

I know I'm a bit late, but it may be worth clarifying the type of scraper, one of these is I assume what Toby refers to - http://www.axminster.co.uk/bahco-650-carbide-scraper

They really are very good. I've done beams, sashes, skirtings etc with mine. The blades are expensive, but worth it.

You press down and the pressure literally cracks and flakes off the paint, very effective if you not tried them before. My joiner lent me his when he was repairing some sashes and sills, I scraped and painted, he repaired and fitted!

 

[Toby Newell]

I meant the Linbide 50mm TC scraper which is better for larger areas but yes I also have several Bahco 650 triangle TC scrapers. I actually have several hundred blades. They are undowithoutable IMO.