Frequently Asked Questions

Welcome to our Frequently Asked Questions page, a compilation of all the queries we regularly get on our key products.
We are sure that you will find the answer to your questions here, and if you don’t then please contact us with your question and we will answer and add it onto our list for future users.

Allweather Roof Coat (1)

A. Yes, you would need to prime the surface with Bitumen Primer first, then apply the AllWeather then Aliminium Paint.

Aluminium Paint (5)

A. The premium grade is more solar reflective than the contractors grade. They both coat the same substrates, but premium is more silver and may be better to use on bitumen that softens due to heat.

A. This is not recommended, as the chippings could lift and disturb the coating. No primer is required, only the felt will need to oxidise for approx 4-6 weeks.

A. White Spirit can be used to break down bitumen. Spray this onto the door and driveway, let it work in and wash down with a hose. It is not necessary to use a power jet.

A. No, we recommend using Cromasol.

A. No, it does not carry a Fire Rating, in its liquid state it will be flammable as it contains solvent, however in its dried state it should be absolutely fine.

Bitumen Paint (2)

A. 24 hours between coats.

A:            No, this will not offer any protection as the paint will soak straight into the wood, it is best to simply felt the roof

Block & Paving Sealer (3)

A. With a power-washer, a stiff brush and lots of elbow grease.

A. Yes

A. It is not recommended as Indian Stone is a natural stone which has porous and non porous areas. Therefore, there is a worry that the stone could end up patchy.

Building Chemicals (1)

A. It is 9-12% hydrochloric acid based.

Cold Gritting (1)

A. Yes you can, however Roofing Felt Adhesive is the better product.

Creotreat (2)

A. Yes not a problem in relation to it being slippery – only issue is that it smells rather strong of solvent

A. Yes no problem

Cromapol (20)

A. It is not necessary however it will make the job a lot easier to do.

A. You will need to brush all the flakes off with a stiff bristled brush first then apply Cromasol.

A. So long as there are no loose pieces of paint, give the roof a really good brush off and get rid of as much paint as possible.

A. No, customer will have to remove the liquid rubber before applying Cromapol.

A. No, as the Aluminium flake will lift off.

A. Not recommended as it would probably not stick. However, you could do a small test patch and see how it adheres.

A. No. The Bitumen will simply bleed through. Use Crompaol Primer.

A. It states on tin up to 72 hours, however in sunny summery conditions 24 hours should be ample. 72 hours would be the worse case scenario in winter.

A. White Spirit is easiest option however you may struggle to remove all the Cromapol because of the fibres in Cromapol.

A. Yes but due to oxidisation in Copper this has to be thoroughly clean and the surface scuffed, almost scoured to get a key.


A. So long as the Bitumen has oxidised yes it is fine.

A. Cromapol is definitely NOT suitable for ponds and it would harm fish.

A. Yes, but you would need to use a masonary paint – Acrylic Water Based.

How long would you leave Cromapol before coating in Masonary Paint? A couple of weeks – when it is firm to touch.

A. Yes – only be very careful to keep record of exactly how much black has been added to ensure true colour match – and – make sure that you thoroughly mix the Cromapol to disperse the black.

A. Yes. However if the asphalt is in bad condition after it has been cleaned down you may have to use a Cromapol Primer, if its in good condition, there should be no problem

A. Yes. You will need to thoroughly wash and clean the surface with disinfectant, then scuff the surface. If it is 30-40 years old and has a build up of ‘patin’ Zinc Phosphate Primer/Inhibitor will need to be applied first & then cleaned again before application.

A. Yes.

A. Yes not a problem. If it is Standing Seam Steel you will need to use a normal Bituminous Primer first, however if it’s a Composite Steel then there is no need.

A. Not ideal or necessary but you would need to leave for a minimum 6 months otherwise Bitumen would bleed through.

A. Yes

Cromaprufe (5)

A. No – Self Levelling is not strong enough – this may crumble. Self Levelling is made to go on top of Concrete not to be used as a Concrete substitute.

A. Yes, you would need to follow the following procedure:

Remove all Lime render;

Point around brickwork with SBR and Neat Cement 1:1 mix;

Apply 2 coats of Cromaprufe;

Blind with clear sharp sand the whole of the area covered;

Plaster over with Lime Render.

A. No – a concrete screed must be laid over the top first – then the tiles fixed with an adhesive

A. Not ideally the best way to achieve a DPC for underfloor heating – usually foil is used – however the Cromaprufe will not attack the Polystyrene as this is emulsion based. Yes this can be applied directly on top, it will remain slightly tacky due to nature/rubberised qualities of material, however as soon as the underfloor heating is activated this will dry.

A. Yes – but ONLY if Self Levelling is mixed with SBR at 1 x 5lt to 1 x bag of S/levelling. Then the underfloor heating can be applied. However the best method to save on time and labour is to make a slurry with 1kg of cement and 1ltr SBR – this will act as the DPC and provide a suitable finish for the underfloor heating.

CromaSeal (1)

A.  Yes however as damp is coming from outside we would recommend that the internal floor is also covered – from floor up the wall. Then a Concrete floor would be required approx 6” on top of the CromaSeal along with an internal block wall to be filled with green concrete to ensure the CromaSeal is not ‘blown’ up from the floor of the wall due to water/damp pressure.

Cromasol (2)

A. Yes no problem at all so long as the Allweather is fully dried and hardened and all solvent has evaporated. You may however need to apply 3-4 coats.

A. No – so long as there are no leaks and it is free of moss and mould.

Exterior Water Seal (5)

A. Yes no problem. Be aware it will have a strong White Spirit smell until solvent has evaporated.

A. Any low pressure “pump action” sprayer.

A. 7-10 years depending on weather conditions etc.

A. Yes it can be overpainted with Water Based Masonry Paint. No it is not Silicone based but Polyoxy Aluminium Stearate.

A. Yes you can with any Water based masonry paint.

FenceTreat (1)

A. No, we wouldn’t advise this to be used on a trafficked surface.

Flexiglass (9)

A. Flexiglass can be trafficked, refer to the Application guide.

A) Before employing a contractor, it is good practice to check qualifications and previous examples of work completed. An Approved Installer can supply a written warranty and proof of Training by way of a numbered Certificate.

A) Two material warranty periods are available subject to application methods, a 10 year and a 20 year.
Refer to the application guide

A) At this time no classification has been issued.

A) Same as GRP.

A) No the two products are not interchangeable.

A) Flexiglass is an overlay/repair product but can be laid onto new boards as a new roof. GRP is classified as a new roof solution.

A) Most common roof coverings, but it is advisable to do a test patch with the primer to check adhesion.

Frostproofer & Accelerator (1)

Fungicidal Wash (2)

A: No not necessarily. It is quite normal for black dots to remain – all spores will have been treated & killed what is left over is the ‘dead plant’. You can over-coat. However, what some people do is to leave the Fungicidal Wash for 4-5 days before scrubbing to allow deeper penetration.

A. Yes he must disconnect the pipe and so long as the roof has been thoroughly washed off he can connect as soon as this is done.

General Company Questions (2)

A. If you have an account with us please email for a copy of your price list or contact your local sales representative.

A. No, sorry we don’t. We operate a strict merchant only policy.

Leadax (8)

A. No it doesn’t

A. Yes it will.

A. Yes it can

Yes, but with self sealing washers.

A. With Leadax sealant (hybrid adhesive) on overlaps and to stick to the substrate. And joints can also be heat welded with a heat gun (200 degrees of heat is required).

A. No, it can be used in the full 6mtr roll length

A. Yes it is suitable for hot air welding.

Leadseal (1)

A. Yes – once this has fully cured i.e. 24 hrs

Liquid Mortar Tone Black (2)

A. Yes colours can be mixed – but be careful regarding colour matching on future mixes. No admix is required – this is ready to use and is an admix in it’s own right i.e. adding to Mortar to obtain desired colour.

A. This is very hard to remove. Can try Jet Washing but this may not remove it completely though.

PRO GRP (16)

A. Ideally no, as the topcoat contains Styrene which can contaminate the water.

A) No the two products are not interchangeable.

A) Flexiglass is an overlay/repair product but can be laid onto new boards as a new roof. GRP is classified as a new roof solution.

A) Before employing a contractor, it is good practice to check qualifications and previous examples of work completed. An Approved Installer can supply a written warranty and proof of Training by way of a numbered Certificate.

A) Yes

A) No

A) Yes with addition of Anti Slip granules added to the Topcoat.

A) This would indicate poor mixing.

A) This is likely water contamination – not enough/too much catalyst added to mix.

A) Typically caused by water contamination/rain/moisture before resin has formed a skin. Also not enough and/or too much catalyst.

A) 5°C and rising minimum, 30°C maximum, at higher temperatures the GRP can cure too quickly.

A) The “System” has a EXT. FAB certification.

A) Providing the product is applied according to manufacturers specification, by an Approved Installer,  (or has attended a recognised competitors training course) Cromar will extend a 25yr Manufacturers Warranty on the materials to the installing contractor.

A) GRP should be applied to O S B Tongue and Groove 18mm Sterling boards.

A) No.

A. 70 linear meters

PU Foams (2)

A. It is pink so the building inspector can recognise it being firefoam.

A. The product has been stored below 5°c.

With all of our aerosol products we would recommend that the tins be warmed up – ideally in a bucket of warm water before use. Always make sure you shake the can thoroughly before use.

Renocoat (1)

A. Yes not a problem at all.

Rubbercoat (1)

SBR (3)

A. Yes, use it neat or you can dilute it up to 50% with water.

A. Yes. You need to make a slurry by mixing 1ltr SBR with 1kg neat cement, paint directly onto wall, then you can can render directly over this once dry.

A. Yes – mix 1lt SBR with 1kg of Cement, apply this to wall & once dry – tile in usual way.

Sealants & Adhesives (3)

A.  Generally, caulk should be applied in warmer weather, ideally above 5°C.

If you do need to apply it try putting your tube in a bucket of warm water before use to bring it up to the right temperature. Or if it is stored in a garage or van, bring it inside the house the night before use so it can warm up. If caulk is applied outside of the temperature range, even high performing caulk like our AlphaChem Caulk, won’t flow as well out of the tube, won’t sit right in the joint and won’t tool as well.

A. We do not currently have one in our range.

A. +5°c is the best temperature as ice crystals form on the surface below and will prevent the best bond.

Torch On Felt (2)

A. It is Polyester based not elastomeric and it will tear but will take some force to do so.

A. SBS is more flexible as it has different polymer in it. SBS is generally a better product.

Vent3 (5)

A. 100mm

A. Yes you can so long as you apply the felt with the coloured side facing the outside of the building (same as in the roof application).

A. Yes no problem at all

A. 12½o

A. Yes it will damage the membrane – solution is to apply the treatment, let it thoroughly dry out then put counter battens up the trusses to fix the membrane onto.

Wood Preservative (6)

A. Yes it will damage the membrane – solution is to apply the treatment, let it thoroughly dry out then put counter battens up the trusses to fix the membrane onto.

A. Yes so long as you use an airless sprayer. And no it should not affect the cable plastic as once the product is thoroughly dry the solvent will have evaporated therefore causing no problem to the cable. If in doubt though, paint some onto the cable and leave to dry, then see if it has been damaged.

A. Yearly

A. It certainly will not be water as that would have been at the bottom of the container. It is more than likely White Spirit that has separated from the rest of the preserver; therefore, a simple shake of the product will disperse the White spirit into the liquid.

A. Yes it kills the insects on direct contact.

A. The active ingredient will Kill ALL Wood Boaring beetles so in this case yes it would.

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