I refuse to use anything else when joining kitchen worktops!
These ZipBolt worktop connectors are FANTASTIC! I wish they were cheaper, but, as a professional kitchen fitter, I feel they are worth their weight in gold. Think of it this way: if you've spent 2, 3, 4, 500 quid or more on worktops, then don't you want to maximise your chance of achieving the best possible joint with the smallest possible gaps? Or do you want to penny-pinch a mere fiver and lower your chances?
ZipBolts can actually improve the quality of the finished joint because they are extremely rapid to tighten. This means no struggling to get the joint closed before your glue begins to gel. With old-fashioned generic worktop connectors (AKA 'dogbones'), they can take 3 or 4 minutes to be tightened (perhaps a little quicker, if you use a ratchet-type spanner, although these can get trapped in the bolt recess, when the tightened bolt shaft draws nearer to the perimeter of the recess, necessitating time-wasting undoing of the joint, to free the spanner), especially when there is insufficient room to fully swing a 10mm spanner back & forth (this scenario happens more often than you might think, because sometimes worktops are 'trapped' between the room walls and the cabinet beneath is not always in a favourable position to allow good access to the connector bolts). With ZipBolts, however, the entire ZipBolt can be held on the tip of a cordless drill-driver (it won't fall off whilst the driver bit is inserted in the ZipBolt end, as the allen bit deeply locates within the socket in the ZipBolt). This means that no room is required to swing any spanner back & forth. It also means one can hold the cordless drill driver under the worktop, without needing to look at it, and WITHOUT risking the connector falling out of the worktop recess during tightening (although I will give you a helpful tip, further down this review), and therefore one can comfortably watch the top surface of the worktop, so as to ensure the worktop is aligned correctly and the joint closing perfectly, with no gaps. With old-fashioned dogbones the 3-4 minutes tightening them can lead to the joint not closing as tightly because the glue begins to gel/skin before it can be fully squeezed out. This is especially true with Colorfill joint sealant, which, because it is solvent-based, begins to skin / gel extremely rapidly.
Speaking of joint adhesives/sealants, never use PVA with chipboard laminate worktops (even if it's waterproof PVA) because PVA is water-based and will consequently cause the chipboard to slightly swell, which will make the top surface of the laminate slightly raised - this does not go back down when it has dried - the worktop remains damaged forever. Be aware that there are some acrylic mastics marketed specifically for worktop joining which are also often water-based, and thus not the best idea. The same goes for water-based cartridge adhesives like 'instant nails', decorators caulk, etc. etc.. Please don't let anyone convince you otherwise - I've witnessed PVA ruin worktop joints on a number of occasions.
When assembling worktop joints, a useful tip is to apply a length of masking tape onto the top surface of each piece of worktop, such that only 1mm or so of the laminate remains visible, adjacent to the glue line of the joint. Consequently, when the adhesive spills out of the joint during assembly, it can be easily wiped away with the majority of the mess affecting only the masking tape. Then that tape can be peeled off and the tiny 2mm line of mess that remains can very easily (but extremely carefully!) be removed with a spatula, credit card, or whatever, and then finally wiped with wonder wipes (or, if you're using Colorfill, use the included 20ml bottle of acetone solvent for cleaning excess away). Always be very careful not to scratch the laminate during cleanup (especially if one side of the joint is fractionally higher than the other. It can be quite challenging to get each side of the joint precisely 100% level with each other - when they are not absolutely 100% level with each other, the risk of damaging the laminate whilst gently scraping excess adhesive away, is increased. Using a plastic scraper, instead of a metal one, is a wise choice, as it is not harder than the laminate, and will therefore be at less risk of scratching it).
Back to choosing suitable adhesive, because it is not water-based, you can safely use generous beads of transparent silicone if you like (enough to ensure 100% of the chipboard will be covered, when the joint is squeezed together, and then the excess wiped off the top surface (Wonder Wipes can make cleaning-up silicone much easier), but if you choose to use silicone, do make sure it's a high quality sanitary one that includes a fungicidal agent (there are many, many silicones on the market, but Dow 785 is, broadly-speaking, about the best widely-available sanitary silicone). Don't be a penny-pincher - buy good quality silicone if you want a good joint that looks good, lasts well, doesn't turn moldy black and doesn't decay or peel away easily.
An improved method is to apply a thin layer of silicone (about 1mm thick x 1 inch wide) to *BOTH faces of the joint*, using a spreader, covering only the bottom two thirds of the joint (and be sure to also leave some bare chipboard, with no silicone, 10mm from the front edge of the worktop), and leaving the uppermost 10mm of the joint (the 10mm nearest the laminate work surface) free of silicone (don't cheat with a bead of silicone - if you are choosing to do what I am about to suggest, then you want to use a spreader to control the silicone so that none of the bottom 2/3rds of the chipboard accidentally misses out on the silicone AND you want to control the silicone so that it doesn't try to squeeze upwards towards the top surface of the joint:
The upper 10mm of the chipboard (and the small area 10mm from the front edge) that has not had any silicone applied, can then have a generous 6mm bead of Colorfill worktop jointing compound applied to *BOTH faces of the joint* (you have used a spreader to control the silicone, but DON'T use a spreader on the Colorfil - if you have applied a 6mm bead to BOTH faces of the joint, there will be ample Colorfill to find its own way into everywhere it is needed, when you assemble the joint - chipboard is very porous and does need quite a generous amount, as you may come to realise if you assemble and temporarily disassemble a joint whilst maneuvering the worktops). Remember, you must work very quickly because Colorfill begins to skin-over very rapidly. However, if you have more than one worktop joint to assemble, then you will need to be slightly more conservative with the amount of Colorfill you apply, in order to have enough to complete the joints successfully. Be as generous as you can, whilst being mindful of keeping half the tube for the next joint. 1 tube of Colorfill should, ideally, not be used to complete more than 2 complete worktop joints (i.e. 2 joints would entail 2 male and 2 female joint faces, and therefore would require the application of 4 beads of Colorfill), so if you know you need to assemble more than 2 joints, please don't make the mistake of penny-pinching; just buy an extra tube of Colorfill and you'll be thankful that you did, because there is nothing worse than not applying enough and thereby risking water penetration in the joint(s), which might ruin 2 or more expensive worktops.
NOTE: Even if you are under a tight deadline, *ALWAYS* DO A TEST-TIGHTEN of the worktop joint *BEFORE* applying any adhesive / sealant / Colorfill; you want to be absolutely 100% certain that the joint fully tightens without gaps, BEFORE you stress yourself with applied adhesive / sealant / Colorfill).
The proposed combination of bottom 2/3rds with transparent silicone and upper 1/3rd (and front edge) with generous amount of Colorfill works very well, as long as you apply the silicone in the controlled fashion described, and as long as you apply the silicone and the Colorfill to BOTH faces, rather than lazily applying to only one face of the joint. You get a well-sealed joint and the benefit of Colorfill to fill any tiny gaps in the joint. After the joint has been cleaned-up using the little bottle of solvent that is supplied in the Colorfill pack, any remaining gaps in the joint can have a bit more Colorfill rubbed-in and this then cleaned-up again with the solvent.
One more thing: if you wish to, you can use a hybrid polymer (also sometimes called 'MS Polymer') sealant-adhesive instead of silicone. This means products like StixAll, Fix-All, Evo-Stik 'Sticks Like', Evo-Stik 007, Geocel theWORKS, ClearFix, and others. Be sure it is transparent, to avoid spoiling the appearance of the joint in the unlikely event some of it reaches the top surface when the joint is tightened.
As I mentioned earlier, never use anything water-based (PVA, acrylics, etc.), and (other than the little tubes of Colorfill I've been discussing, which do work appropriately for this task) never use a solvent-based mastic-type adhesive like GripFill etc., as they're not suitable for the specific task of worktop joints.
*I promised a helpful tip to reduce connectors falling out of the worktop recess during tightening. When you lift the FIRST worktop into place, on top of the cabinets, before you do this, you can flip the worktop upside down (place some cardboard on top of the kitchen cabinets so the laminate surface doesn't get damaged). Whilst this first worktop is upside down, you can insert all of your connectors into the recesses in the chipboard (make sure you only insert the 'dumb' ends of the connectors into this first worktop, so that the tightening nut (or tightening allen socket, if you are using ZipBolts) is hanging in mid-air, to eventually to be inserted into the recesses in the second worktop. When you are doing this, be sure to check that the connectors are loosened sufficiently that when the second worktop is lowered into place, the connectors will not foul / get crushed, but will freely insert themselves into the recesses of the second worktop, without hindrance. Obviously, you need to think carefully about which of your worktops will be the 'first' one, and which one will be the 'second' one to be lifted into place, because you want the second worktop to be the one that will have the bolt ends accessible to the tool you will be using for tightening purposes. It can be tricky gaining access to those pesky bolts, with some corner cabinets, so think this through, thoroughly! (and you may need to drill a 25mm hole in the front rail of the cabinet, in order to access the tightening nut of the front bolt - this is yet another good reason to always do a dry-run of assembling the joint, before any adhesive/sealant is applied to the joint. Anyway, assuming you've carefully figured out which will be your first worktop to lift into place, let's go back to the point where you flipped it upside down onto a piece of protective cardboard, on top of the cabinets. Whilst it's upside down, insert the 'dumb' ends of the worktop connectors into their recesses, and then you can sneakily drive a *SMALL* screw, diagonally, into each of the round recesses, in such a way that it 'traps' the bent metal plate of the connector in the recess. These screws should not be bigger than 3.5 guage x 20mm long, or you may risk flaking the chipboard (or, worse, going through the laminate surface on the face side!!). Alternatively, Unika make some plastic clips that trap the shaft of the connector into the shaft recess in the chipboard (that product is called 'EasiBolt'. The Unika steel worktop connectors are bog-standard dogbones - what you're actually after is the included plastic component that traps the shaft - in a best-case scenario, you'd rob these plastic components and apply them to ZipBolt connectors). You can use either the tiny screws method or the plastic 'Easibolt' component method, in order to hold your wortop connectors firmly in their recesses prior to the joint being tightened, and they are EQUALLY successful, so you don't really need to be buying 'Easibolts' for this purpose unless you prefer to do that. Of course, if you're experienced, or simply confident in your abilities, you can choose not to use either of these methods, but I do recommend using one of these methods as they can make life much easier when assembling the joint, especially considering that the faster the joint is successfully assembled, the smaller the joint gap is likely to be, and everyone wants the smallest possible gap in their worktop joints, don't they? There's nothing worse than having a worktop joint loaded with adhesive/sealant, and the clock ticking, and then a joiner falls out of one of the recesses and you have to dismantle the entire joint, lift the worktops off the cabinets and rescue the bolt and re-insert it.
Lastly, some tips for routing the worktop joint, prior to assembly:
Never use speedclamps / trigger clamps / qwikclamps, etc. to hold the jig to the worktop - they are great for many tasks, but, for routing kitchen worktops, always use traditional screw-thread G-clamps. The reason is that G-clamps do not accidentally 'let-go' like other types of clamps sometimes do. G-clamps can also apply more pressure, to reduce risk of the jig slipping across the slippery laminate worktop surface during routing, although one obviously needs to be careful not to overtighten G-clamps, as that may squash the chipboard or fracture the laminate surface. Oh, and *ALWAYS* protect the laminate surface from the clamp, by using a thick piece of cardboard or (better) a scrap of plywood in between the laminate and the clamp-jaw
Secondly, I recommend you buy a decent quality 12.7mm cutter, rather than a generic Chinese cheapo one, because cheap cutters are sometimes not accurately sized, but, more importantly, chipboard worktops and hardwood worktops are very abrasive and can rapidly blunt low-quality tungsten carbide. When a cutter gets blunt, it will chatter/vibrate more during routing which can reduce the quality and accuracy of the cut, put more stress on your router collet / bearings / motor, and even risk shattering the cutter (always wear goggles when routing!).. Also bear in mind that even the best quality cutters should not be used to cut more than 2-3 complete worktop joints (comprising 4-6 joint faces and their associated 12-18 connector-bolt recesses). That might sound extravagant, but routing worktops is brutally taxing on router cutters.
Always remember to cut worktop joints in several passes (10mm deep, then 20mm deep, then 30mm deep, then 40mm deep), as this massively reduces stress on the router cutter and the router itself, and maintains accuracy of the joint being cut.. This is important.
Each time you begin a router cut, as the cutter first comes into contact with the material and begins to cut, be ACUTELY careful to make this happen *EXTREMELY* slowly, to absolutely minimise the possibility of chipping the laminate (or timber grain, although timber tends to be less problematic in this regard). Economy laminate worktops are the worst offenders for this, as the laminate tends to be paper-thin and therefore lacks sufficient intrinsic strength and additionally is often not fully bonded to the front edge of the chipboard worktop - the net result is that it will shatter & chip absurdly easily, so a mega-slow entry feedrate may be necessary to overcome this risk.
When you use a router jig, you will notice that the 30mm guidebush does not fit tightly within the jig slot - you will find that there is a small amount of 'play'. When routing the 10mm deep, then 20mm deep, then 30mm deep, then 40mm deep incremental passes, try to apply a little sideways pressure so as to bias the router cutter AWAY from the final face of the joint you are routing (i.e. as you are pushing forwards, apply moderately firm pressure towards the right. Not too much pressure, but do be determined, as the router cutter will naturally try to tug the router to the left). Only after the joint has been cut to full-depth should you make a final 'finishing' pass, whereupon you should apply a little sideways pressure to the router, this time TOWARDS the face of the joint you are cutting (i.e. pressure towards the left side of the jig slot). This will give you the best chance of accuracy, as the cutter will sometimes vibrate / chatter during the incremental passes, so you want to save a nice smooth 'skimming' pass for the final finishing of the joint face. At all times, whenever you are routing, keep your movements smooth, but, at the same time, keep your muscles somewhat tensed, with vigilant concentration & determination to maintain control in case the router judders or snatches the material. In general, try to push the router away from you, rather than being tempted to stand sideways-on to the direction the router is travelling, because one's arm muscles are better capable of controlling any jerks/snatches, in that manner.
Incidentally, for those of you who are confident enough with a jigsaw that you can control it very well without risk of the cut wandering, you can rout the first 10mm-deep pass, and then switch off the router and carefully jigsaw along the middle of the groove you've just routed (using the jigsaw WITHOUT unclamping the routing jig). Once you've jigsawed off the bulk of the waste material, you can then resume your incremental passes with the router. This jigsawing method is only to reduce wear & tear on the router cutter (and reduce the amount of chipboard dust produced during the joint-cutting procedure), and is not strictly necessary, but is worthwhile if you are confident you can jigsaw without damaging the routing template or the worktop joint.
Here's a major point: One of the most important things to understand is that when you rout a worktop (and this holds true for chipboard laminate worktops AND for solid timber worktops) you must ALWAYS rout in the direction of BEGINNING the cut moving *INTO* the front edge of the worktop. If you begin to rout by entering into the back edge of the worktop, and exit through the front edge of the worktop, you are 99.999% guaranteed to destroy the front edge of your worktop, because the rotation of the cutter blades will splinter the laminate or wood grain (therefore, it is sometimes necessary to rout the joint with the worktop upside down, to ensure the direction traveled by the cutter is correct). This is such a vital thing to understand! So much so that if you are confused by what I am describing, then please just spend a couple of hundred quid getting a professional to cut the joints. If you get this aspect wrong, you may waste several hundred quid with irreparably damaged worktops that will need new ones buying to replace them. I've seen a Festool instructional video online which unwisely contravenes this advice, presumably because they feel that 'cutting-on-the-climb' is not risky, but I strongly urge people to avoid doing so, or they may live to regret an expensive mistake.
It can sometimes happen that you may have accidentally tilted the router, fractionally, during routing, or that the routing jig (or router itself) may have had some sawdust under it which meant it did not sit fully flat on the worktop during routing, either of which occurrences can lead to the bottom portion of a worktop joint closing before the visible top portion of the laminate has fully closed, thus leading to the top portion never fully closing, and creating an unsightly gap. This is one reason why I strongly advise always tightening a couple of bolts to test the joint BEFORE any adhesive is applied.
Another thing that can sometimes cause the bottom portion of the joint closing before the top portion fully closes, is when one or more of the worktops is warped/bowed along its length. Unfortunately, this is surprisingly common, especially with cheaper worktops that have thinner laminate layers, and/or a thinner chipboard core.
In a case where the lower portion of the joint closes before the top portion does, but NOT due to the worktop being warped/bowed it is possible to rescue the situation, with great care and some skill. In this first scenario, gently use an accurate set-square to check if the routing was truly accomplished at 90 degrees to the top surface of the laminate, being careful not to chip the laminate edge with the set square. If the cut joint isn't at 90 degrees, then, generally-speaking, you can't realistically remedy this using the routing jig because you can't easily re-align the jig (unless you are skilled with very accurate measuring, marking, and alignment for the appropriate 8.65mm offset), because the location pegs may no longer have a full datum to rest against (although this may vary depending on the jig design you have). Therefore, a better solution to remedy a cut joint that isn't truly at 90 degrees, is to pack your jig away, remove both the 12.7mm cutter, and the 30mm guide bush, from your router, and then insert a large bearing-guided flush-trim cutter (the blades of which must be at least 33mm long, if your worktops are 38mm thick, because the ball bearing MUST be able to run along the edge of the actual laminate layer, and not just the chipboard!). This type of cutter can be used in such a way that the ball bearing of the cutter contacts the uppermost 5mm of the chipboard joint face, including the actual edge of the laminate layer itself (i.e. where the Colorfill will eventually be applied). However, please be super careful to ensure that you always cut in the direction of approaching the front of the worktop to begin the cut, for the reasons described earlier. When you are stressed with installing your worktops, it is easy to forget about this, and end in tears! Just relax and take your time to think things through very carefully. The importance of cutting direction means that in order to successfully remedy a non-90 degree cut, using the method I am describing, sometimes one will need to employ a flush-trim cutter that has the ball bearing located at the top of the cutter, and sometimes the ball bearing will need to be located at the bottom of the cutter (so that, when required for appropriate travel direction of the router, the router base can run along the bottom surface of the worktop whilst the cutters ball bearing can still run in contact with the 5mm portion of the laminate that is closest to, and includes, the edge of the actual laminate layer.
Trend C199X1/2TC, CMT 657.994.11B, and Wealden T8152B-1/2 'Multi Trim' cutters have 50mm blades and have ball bearings at both the top and bottom of the cutter, so can be adjusted to function in either scenario. Perhaps Axminster might offer something similar, if you ask. Incidentally, for this particular kind of rescue mission for worktop joints, I suggest you avoid using up-shear or down-shear cutters, as there is a risk of accidentally using them with a shear direction that may chip the laminate. Using a ball-bearing guided flush-trimmer can successfully adjust the joint to become truly 90 degrees in relation to the top surface.
In the *second* scenario, where, *because of one or more worktops being warped/bowed*, the worktop joint closes at the bottom before it does at the top (again, leaving an unsightly gap), then a flush-trim bit will not necessarily remedy the problem (unless one is experienced with applying a masking-tape packer to one side of the bottom of the router base, whilst making a cutting pass with the worktop laminate-side-up, in order to deliberately induce a slight lean to the router, with the aim of creating a slight undercut to the joint face, such that the top portion of the worktop joint closes fractionally before the bottom portion). I really don't recommend that method, as it's risky and the end result will be a bit of a cobble, since, even though the joint may close tightly at the visible top portion, it doesn't remedy the assembled joint not being entirely flat, due to the worktop(s) being bowed and thus creating a slight peak (i.e. placing the edge of a ruler onto the top surface of the completed joint would reveal a rocking motion). In fact, undercutting the joint in such a manner may well make it even more difficult to avoid such a peak, since the closed joint will not resist such a peak, to any extent, as it would at least try to do, when the connector bolts are tightened, if both faces of the joint were cut exactly at 90 degrees. Therefore, in this second scenario, the first thing to do would be to CHECK that the joint faces were correctly routed at 90 degrees (if not 90 degrees, then follow the steps to legitimately rout to exactly 90 degrees, using a bearing trim cutter, in the fashion earlier described for the first scenario). Assuming the actual routing of the joint faces is correctly at 90 degrees (or has been subsequently corrected to be at 90 degrees), then, generally-speaking, all one can realistically do, any further, is gently prop-up the far end of the worktop, whilst the other end is glued and assembled, and the zip-bolts fully tightened, then tightly and generously screw both sides of the underside of the assembled joint down to the cabinets, at the front and rear of the cabinets (being careful both to use screws that are not long enough to puncture the top surface, and to thoroughly check that both parts of the joint remain perfectly level with one another, at the top surface of the laminate), and only then remove the props/chocks from the other end of the worktop, with the hope that the joint, by virtue of being tightly bolted together, and firmly screwed to the cabinets, will remain aligned , fully-closed, and intact. Generally, a satisfactory result can be obtained this way.
Lastly, if you choose to use ZipBolts, don't use an impact driver to tighten them - the right-angled gearing mechanism employed within ZipBolts is surprisingly robust, but it does have limits to the amount of torque it can withstand, so be sensible and only use MODERATELY high torque using a cordless drill-driver or manual allen driver. If you ignore this, you may strip the gearing inside the ZipBolt - if this happens, the good news is that the bolt won't spring loose, but the bad news is that you'll struggle to subsequently adjust your worktop joint if both sides of the laminate aren't perfectly level with one another.
I hope no one objects to me typing so much, here, but I sincerely wish whoever fits worktops to have the happiest end result, be they amateurs or professionals.
With that said, I highly recommend spending a little extra to obtain these genuine 'ZipBolt' branded worktop connectors, as they significantly increase one's chances of success, and Axminster price them competitively, too. Just note that Axminster stores seem to have quite erratic stock levels of these connector bolts, so phone or browse before you travel to a branch to buy some.